Highly recommended: Sharing experience in metal stamping die design

Dec 02, 2025

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★Concept of Stamping Dies
Stamping dies, also known as punch dies, hardware dies, or metal stamping dies, all refer to the same thing: a pressure processing method that uses a die fixed on a punch press or press to apply pressure to metal or non-metal sheets, causing the material to separate or form, thereby obtaining parts with specific dimensional requirements and acceptable appearance quality. There are many types of dies; here I will mainly focus on metal stamping dies, which I am familiar with.

Products processed using dies are basically the same in size and appearance, with little difference. This is because they allow for rapid forming, high production efficiency, stable product quality, and meet precision requirements. Material utilization is high, operation is simple, and the labor intensity for workers is low. The technical requirements for operators are not high; generally, anyone can learn quickly within a day or two, some even in just a few minutes. If you are a main line operator, you need to learn to operate the punch press, feeder, leveling machine, and die disassembly and assembly, etc. These are all very simple tasks; strength and a willingness to work hard are all that's required.

Be mindful of safety. Do not put anything inside the mold. Wrenches, scissors, and other tools should not be left inside. After a mold repairman has worked on the mold (professional term: mold repair), check before you start to see if they have left anything inside. While repairmen generally don't make this mistake, it's still good to be aware. Avoid damaging the mold or injuring yourself or your hands. Safety is paramount in this job. If something is accidentally left inside the mold, a sudden impact from the punch press could damage it, and if the contents fly out, you could be injured.

Sometimes, when a forklift is lifting a mold, it might fall. Never try to catch it with your hands. Keep your distance. It's okay if the mold breaks, but don't let it hit you. When an overhead crane is lifting a mold, keep your distance to avoid being hit by it.

Working in the mold industry or dealing with molds is prone to accidents. Newcomers to the factory should pay special attention to these safety precautions.

★Introduction to the Structure of Stamping Dies
The structure of stamping dies and stamping molds is largely similar. Different dies are designed according to different product characteristics and requirements. Different die structures have different functions and produce different products. Generally speaking, some are simple, and some are complex. However, no matter how complex the structure, its basic structure remains unchanged, consisting of several templates, modules, and standard parts.

Die is generally assembled from several templates and parts (called inserts or insert blocks) and standard parts.

The typical stamping die structure, specifically the templates from top to bottom (including code numbers), is as follows:
Upper die templates include: Upper support plate, upper pad, upper die holder (UPU), upper backing plate (UBU), upper clamping plate (PHU), stop plate (PPS), stripper plate (PSU);
Lower die templates include:
Lower die plate (DIE), lower backing plate (LBD), lower die holder (LPD), lower pad, lower support plate;
Other less commonly used templates include:
Upper cover plate (CVU), extrusion plate, upper die plate, lower stripper plate... Material plate, lower stop plate, lower clamping plate, male mold, female mold, etc.; Some mold parts include: Upper mold inserts and blocks: clamping plate insert, stripper plate insert, punch, etc.; Lower mold inserts and blocks: lower mold insert, lower mold cutting edge, etc.; Standard parts: springs, hexagonal screws, stop screws, wire springs, equalizing sleeves, guide pillars, guide bushings, equalizing sleeve washers, dual-purpose pins, ejector pins, etc.; Non-standard parts: external positioning, internal positioning, pitch positioning, external limit pins, internal limit pins, etc.; ★ Stamping die numbering Stamping die numbering, This is generally written like this (for example): Engineering mold: 90-KNMF0125RAH, 90-KNMF0125RAA, 90-KNMF0125RBB Progressive mold: 90-KNMF0125SAA, 90-KNMF0125SBB In the RAH section, R represents the engineering mold, H represents a total of eight sets (from A-H, namely RAH, RBH...RHH), and A represents the first set; RAA or RBB represents a riveting mold, such as a stud rivet, etc. Rivet springs, etc.; In SAA and SBB, S represents progressive die, 0125 represents the die number, and the preceding F represents the year. The die number indicates the year it was produced, such as F0125 or G0125. If F represents 2010, then a die produced in 2010, F0125, can be simply referred to as "Die 125." Dies produced in 2011 will begin with G, and if you then say "Die 125," people will likely assume you are referring to die G0125.

Other components, such as the upper clamping plate (PHU), are numbered 90-KNMF0125SAAPHU, with the clamping plate insert being 90-KNMF0125SAAPHPA001. If this continuous die has two sections, then A and B are used after the number 90-KNMF0125SAAPHU to indicate this. In this case, the clamping plate for the first section should be 90-KNMF0125SAAPHUA, and for the second section 90-KNMF0125SAAPHUB, with the clamping plate insert being 90-KNMF0125SAAP. HPA001, 90-KNMF0125SAAPHPB001; Lower Die: 90-KNMF0125SAADIE, 90-KNMF0125RAHDIE Regarding other part numbers not explained here, a brief explanation is provided: ★Common Stamping Materials and Selection The properties of materials used in stamping are closely related to stamping production. Their properties directly affect stamping process design, stamped part quality, and product lifespan, as well as the organization of balanced production and stamped part production costs.

When selecting materials for stamped parts, not only performance characteristics should be considered, but also the performance requirements of stamping processing and subsequent processes should be met. The basic requirements for materials in stamping processing are as follows:

1. Good Stamping Forming Performance For forming processes, such as stretching, bending, step forming, and convex forming, the material should have good stamping forming performance, i.e., good resistance to breakage, good mold adherence, and shape retention. Otherwise, the product is prone to deformation and breakage, causing difficulties in mold repair. For the separation process, the material must possess a certain degree of plasticity.

2. High Surface Quality: The material surface should be smooth and free of defects or damage. Materials with good surface quality are less prone to breakage during forming, less likely to scratch the mold, and produce parts with better surface quality.

3. Material Thickness Tolerance Must Meet National Standards: Because a certain mold clearance is only applicable to materials within a certain thickness range, excessive thickness tolerance not only directly affects the quality of the parts but may also lead to scrap. In processes such as correction bending and shaping, excessive positive thickness deviation may damage the mold or press.

1. Commonly Used Stamping Materials: The most commonly used materials in stamping production are metallic materials (including ferrous and non-ferrous metals), but non-metallic materials are sometimes used. Ferrous metals mainly include ordinary carbon structural steel, high-quality carbon structural steel, alloy structural steel, carbon tool steel, stainless steel, and electrical silicon steel; non-ferrous metals mainly include pure copper, brass, bronze, and aluminum; non-metallic materials include cardboard, laminate, rubber sheets, plastic sheets, fiberboard, and mica.

The supply of metal materials for stamping is generally in the form of sheet metal and strip metal of various specifications. Sheet metal can be used for the production of engineering dies, while strip metal (coils) is used for the production of progressive dies, and can also be used for the production of engineering dies. Sheet metal has a larger size and can be used for stamping large parts. It can also be cut into strips according to the layout dimensions for stamping small and medium-sized parts. Strip metal (also known as coil metal) has various widths and can be extended to tens of meters in length. It is supplied in coils and is suitable for automatic feeding in the mass production of progressive dies.

For information on the grades, specifications, and properties of various materials, please refer to relevant manuals and standards.

2. Rational Selection of Stamping Materials
The selection of stamping materials should consider the usage requirements of the stamped parts, the stamping process requirements, and economic factors.

(1) Rational Material Selection Based on the Usage Requirements of Stamped Parts
The selected materials should enable the stamped parts to work normally in the machine or component and have a certain service life. Therefore, the selected materials should meet the requirements for strength, rigidity, toughness, corrosion resistance, and heat resistance, etc., according to the usage conditions of the stamped parts. (2) Material Selection Based on Stamping Process Requirements

For any stamped part, the selected material should be able to stably form a qualified product without cracking or wrinkling according to the requirements of its stamping process. This is the most basic and important material selection requirement. Therefore, the following methods can be used for reasonable material selection:

① Trial Stamping. Based on past production experience and possible conditions, select several sheet materials that basically meet the requirements of the stamped part for trial stamping. Finally, select the one without cracking or wrinkling and with a low scrap rate. This method yields relatively intuitive results, but it has a significant degree of randomness.

② Analysis and Comparison. Based on the analysis of the properties of stamping deformation, compare the maximum deformation degree during stamping with the limit deformation degree allowed by the stamping performance of the sheet material. Use this as a basis to select sheet material suitable for the stamping process requirements of this type of part.

In addition, sheet materials of the same grade or thickness are further divided into cold-rolled and hot-rolled. In my country's domestic sheet materials, thick plates (t>4mm) are hot-rolled plates, and thin plates (t<4mm) are cold-rolled plates (hot-rolled plates also exist). Compared with hot-rolled plates, cold-rolled plates have more precise dimensions, smaller deviations, fewer surface defects, a brighter appearance, and a denser internal structure, resulting in superior stamping performance. (Note: t generally represents thickness in dies; for example, the thickness of the template and the thickness of the material can both be represented by t.) (3) Select materials reasonably according to economic requirements. The selected materials should be as inexpensive, readily available, and economical as possible, while meeting the requirements of performance and stamping process, in order to reduce the cost of stamped parts. ★ Classification of stamping dies. Stamping dies can generally be classified into two types: engineering dies and progressive dies. Engineering dies can be further divided into compound dies, drawing dies, riveting dies, etc. The structure and function of these dies are briefly introduced below. Engineering dies: also known as "single-operation dies," refer to dies that can only complete one stamping operation in one stamping stroke. After this operation is completed, the product needs to be removed from the die manually or by a robot and then placed into the next die to continue production until the last operation of the die is completed, at which point the entire product is considered finished. This type of mold is simple to repair, but production is time-consuming and labor-intensive, requiring significant manpower and time costs, and resulting in a high product scrap rate.

Compound Molds: Common compound mold structures include compound blanking and compound stretching molds. This mold structure differs slightly from other engineering mold structures. Its punch (also called male mold or punch head) is designed in the lower mold. The other mold plates are, in order, a lower clamping plate (fixing the punch head), a lower stop plate, and a lower stripper plate (external stripper). The upper mold consists of a female mold (or cutting edge), an inner stripper plate, and an upper backing plate. The inner stripper uses a height-equal sleeve suspended on the upper backing plate, and is then supported by a push rod or spring. For example, in a compound mold used for blanking, the inner stripper generally only needs to extend 0.50mm out of the female mold; it cannot be lower than the female mold, otherwise the female mold cutting edge may break or fail to strip the material. The force of the inner stripper must be sufficient to eject the product from the female mold. Generally, if the material is relatively thick, we use a nitrogen spring.

Progressive die: also known as "progressive die", refers to a die that completes two or more stamping processes simultaneously at different stations during one stamping stroke. This type of die is more difficult to repair and requires experienced fitters to operate, but it is very efficient in production. If the stamping speed is fast, thousands of products can be produced per hour, saving labor and time costs, and the product scrap rate is low.

★Spring Compression and Calculation

A set of stamping dies requires a considerable amount of elastic materials, including springs of various specifications, urethane, nitrogen springs, etc. Different elastic materials are selected according to different needs. For bending and punching, ordinary flat wire springs are generally sufficient, such as brown springs, also known as coffee-colored springs. If the force is insufficient, nitrogen springs are added, although the cost is higher. Urethane is generally used for drawing dies, forming dies, or for flattening.

Urethane is excellent for deep drawing dies, although nitrogen springs can also be used. Other components such as ejector pins, floats, and dual-purpose pins generally use wire springs or yellow springs, as long as they allow for material removal without leaving marks or deformation on the product. Urethane is characterized by relatively even force, but its lifespan is relatively short; it may crack, fail, or wilt after a period of production. Therefore, it is generally used less frequently, and nitrogen springs are more commonly used. Urethane is widely used for flattening.

Springs, including flat wire springs and coil springs, are used for material release and compression. The spring force directly affects the smoothness of mold production and the quality of the produced products. Insufficient spring force can lead to various problems such as product deformation, failure to release material from the mold, difficulty in removing the product from the mold, material residue, and premature wear of cutting edges and punches.

Flat wire springs are generally classified by color: brown, green, red, blue, and yellow, with force decreasing in that order. Different colors indicate different strengths and compression levels.

There's a simple method for calculating spring compression. I learned this from my mentor when I first started learning mold making in the factory, and I didn't know much about it yet: First, measure the total height of the spring. Then, place the spring in a vise and lock it. Next, use calipers to measure the length remaining after the spring is clamped. Subtract this number from the total spring length, then divide by the total length. This method works for any spring. For example, a brown spring is 60mm long; after being clamped in the vise, it should have about 45.6mm remaining. Subtract 45.6 from 60mm to get 14.4. Divide 14.4 by 60mm; the result is 0.24. This is its compression.

For springs designed for different production cycles, such as 1 million, 500,000, or 300,000 cycles, a higher compression value results in a shorter spring lifespan and a shorter mold lifespan (of course, a broken spring can be replaced). After a period of mold production, the spring may lose its strength, and a lower-quality spring might even break inside the mold. The compression of a spring is generally calculated based on 300,000 cycles. This means that the spring might lose its strength after 300,000 cycles. Of course, the lifespan of most stamping dies isn't that long. Alternatively, the maximum compression can be used for calculation. However, calculating based on maximum compression only ensures the spring won't burst inside the die. A more tightly compressed die also benefits the flatness of the product.

The specific compression values are shown in the table below:
Color
100 cycles
500,000 cycles
300,000 cycles
Maximum Compression
Brown Spring
16%
18%
20%
24%
Green Spring
19.20%
21.60%
24%
28%
Red Spring
25.60%
28.80%
32%
38%
Blue Spring
32%
36%
40%
48%
Yellow Spring
40%
45%
50%
58%
Maximum Compression (This spring can...) The maximum compression of a spring is equal to its free height multiplied by its maximum compression ratio. For example, a brown spring with a length of 60mm has a maximum compression of 60 * 24%, approximately 14. This spring can be compressed a maximum of 14 millimeters, and its maximum stroke is 14 millimeters. The die stroke must be less than 14 millimeters. Exceeding 14 millimeters may cause the spring to fail, deform, break inside the die, or even cause the die to explode, preventing the press from pressing down.

Before die assembly, the spring compression must be calculated to ensure it is appropriate. This prevents problems such as die failure or explosion during trial runs.

★Determining the Blanking Die Clearance: The blanking clearance is generally determined using empirical formulas and charts.

Those who have worked as stamping die fitters and designers for a long time naturally possess rich experience and a deep understanding of various products, including their material, dimensional, and appearance precision requirements. They also understand how to design dies to ensure the smooth production of qualified products and how to reduce the frequency of die repairs and maintenance. When given a product drawing, they can readily visualize the approximate structure of the die and have a clear grasp of all the relevant parameters.

The clearance between the punch and the cutting edge significantly impacts the quality of stamped parts and the lifespan of the stamping die. Therefore, when designing a stamping die, it is crucial to select a reasonable clearance to ensure that the cross-sectional quality and dimensional accuracy of the stamped parts meet product requirements, that the required blanking force is low, and that the stamping die life is long. However, the reasonable clearance determined from the perspectives of quality, blanking force, and stamping die life is not the same value, but rather a close approximation.

Considering the deviations in die manufacturing and wear during use, only an appropriate range is typically chosen as the reasonable clearance in production. As long as the clearance remains within this range, good parts can be stamped. During the production process, stamping dies wear down, causing the clearance to increase. Therefore, the minimum reasonable clearance value must be used when designing and manufacturing new stamping dies.

Based on the experience of experienced factory workers over many years in researching and improving dies, smaller clearance values should be used for parts requiring high dimensional accuracy and perpendicularity of the cross-section. For stamping parts with lower requirements for perpendicularity and dimensional accuracy, the focus should be on reducing the blanking force and increasing the life of the stamping die, thus a larger clearance value can be used. Its value can be calculated using the following empirical formulas: Soft materials:
Material thickness t < 1 mm, punching clearance c = (3% ~ 4%)t
t = 1 ~ 3 mm, c = (5% ~ 8%)t
t = 3 ~ 5 mm, c = (8% ~ 10%)t
Hard materials:
t < 1 mm, c = (4% ~ 5%)t
t = 1 ~ 3 mm, c = (6% ~ 8%)t
t = 3 ~ 8 mm, c = (8% ~ 13%)t

The following is theoretical knowledge from textbooks, mainly based on ensuring the fusion of upper and lower cracks to obtain a good cross-section.

Based on the relationship of triangle ABC, the clearance value c can be obtained as:

c = (t – h0) tanβ = t (1-h0/t) tanβ
Where, h0-- the die cutting depth; β-- the angle between the direction of maximum shear stress and the vertical direction.

As shown in the formula above, the clearance *c* is related to the material thickness *t*, the relative penetration depth *h0/t*, and the crack direction *β*. *h0* and *β* are related to the material properties; the harder the material, the smaller *h0/t*.

Therefore, the main factors affecting the clearance value are the material properties and the material thickness. The harder or thicker the material, the larger the clearance value.

★The Entire Process of Stamping Die Development

How are stamping dies manufactured step by step?

A complete stamping die development process begins with the customer sending the product drawing to the head of the stamping die design department. The design manager confirms whether the department's technology allows for the production of the product. If so, the design personnel create the drawings and prepare the materials. The necessary plates for the die are purchased, and rough machining is performed to allow for adjustments. The template thickness is ground to a certain dimension, generally leaving a allowance of 50 strips (0.50mm) on both sides. After rough machining, the die is sent for heat treatment.

Simultaneously, the design department holds a seminar to develop the step-by-step process drawings for the product and create the strip drawing. A product cannot be manufactured through a single process; it must coordinate with other processes to produce a qualified product. After the product process diagram is finalized, the designers begin designing the mold.

Once the design team has drawn all the parts of the mold, the mold can officially begin processing. First, the template is ground to the correct dimensions. Then, electrical discharge machining (EDM) is performed to mark the wire holes. Next, wire cutting is used to cut the insert holes, cutting the cutting edges, and blanking. The mold is then sent to a milling machine or CNC machine for countersinking and repositioning. Finally, quality assurance checks the parts; any that fail are returned to the responsible department for further processing. Once合格 (qualified), the mold is sent to the warehouse for storage.

Finally, the fitter retrieves the parts from the warehouse and begins pre-assembly preparations, such as chamfering, deburring, removing rust, confirming dimensions, checking that all areas are machined correctly, and ensuring there are no missing holes or screw threads. Once the mold parts arrive, assembly can begin temporarily, assembling the mold piece by piece. This process saves considerable time compared to assembling only when all parts have arrived.

After the mold assembly is complete, trial molding and debugging begin until the mold can produce products that meet the required dimensional accuracy and appearance quality. Then, samples are sent to the customer for approval. Once the customer confirms the approval, all work on this mold set is considered officially complete, and it's ready for production. After that, it's all about mold repair and maintenance. If the mold is fine, the fitter's job is smooth. Being a fitter is quite stressful; you never know when the mold will break, and if it does, you have to repair it immediately. The more repairs you do, the more troublesome it becomes. Of course, if the mold is assembled well and everything is done correctly, there won't be many problems.

★What is a punch? How is punch length calculated?

How is punch length calculated?

First, let's examine what a punch is and what role it plays in a stamping die.

A punch is a convex die mounted on a clamping plate. It generally performs functions such as punching, cutting, bending, creating steps, creating bulges, creating strips, drawing, and riveting studs. These can all be simply referred to as a "punch."

The length of the punch for punching is equal to: the thickness of the clamping plate + the thickness of the stop plate + the thickness of the stripper plate + the material thickness + (1-2) millimeters. The length of the punch for a 90-degree bend is equal to: the thickness of the clamping plate + the thickness of the stop plate + the thickness of the stripper plate + the material thickness plus one or two millimeters. Adjustments can be made as needed during trial molding. Other angled bend punches generally have a certain angle at the front; calculations should be flexible and based on the angle.

The length of the punch for stepping is equal to: the thickness of the clamping plate + the thickness of the stop plate + the thickness of the stripper plate + the step height.

These are just fixed rules; actual application depends on the situation. They won't be explained in detail here, but you'll understand them naturally as you gain more knowledge about stamping dies.

★Composite Dies, What are Composite Dies?

A composite die is a die that completes multiple stamping processes in one stroke of the press. Processes that can utilize compound mold structures include: blanking, cutting, bending, forming, shaping, stretching, upsetting, extrusion, and flanging. The appropriate process can be selected flexibly based on actual needs. Generally, four or fewer processes are recommended; too many will make mold manufacturing difficult, reduce mold strength, increase damage, lead to more frequent mold repairs, and raise mold costs. Using compound molds can improve product precision and production efficiency.

For example, when stamping a washer, two molds can be used to punch the hole and blank the material separately. Punching punches the central hole, while blanking shapes the outer form. If this can be done in one step with a single mold, it's a compound mold. Single-step molds also include stretching and trimming. Any mold that completes two or more steps in one operation is called a compound mold.

Due to the different combinations of processes in compound molds, the ejector devices also vary. I'll share some common compound mold structures with you when I have time.

The structure of a compound die for blanking or upward bending: The punch (also called the male die or striker) is located in the lower die. The other die plates are, in order, a lower clamping plate (to fix the punch), a lower stop plate, and a lower stripper plate (external stripper). The upper die consists of a female die (or cutting edge), an inner stripper plate, and an upper backing plate. The inner stripper plate uses a height-equalizing sleeve suspended on the upper backing plate, and is then supported by a push rod or spring.

For compound dies used for blanking, the inner stripper plate should generally extend 0.50mm out of the female die. It should not be lower than the female die, otherwise the female die cutting edge may break or the material may not be ejected. The force of the inner stripper plate must be sufficient to eject the product from the female die. Generally, if the material is thick, a nitrogen spring is used.

Compound dies are a type of mold structure and can be classified as engineering dies because they are frequently used in engineering molds. Often, an entire engineering mold uses a compound die structure.

Continuous dies are generally used for upward forming, upward bending, upward embossing, upward dotting, and upward cornering, and often employ a compound die structure.

★When using a compound die to punch embossing, must the punch extend above the stripper plate?

Today, I received a question from a student: When using a compound die to punch embossing, must the punch extend above the stripper plate?

The answer is yes, otherwise how can you punch embossing?

I suggest this student review what a compound die is and how to calculate the punch length. Once you understand these concepts, you'll naturally understand how to answer this question.

When using a compound die structure to punch embossing, the punch length is equal to: clamping plate thickness + stop plate thickness + stripper plate thickness + embossing height.

In other words, during punching, when the die is fully depressed on the press, the punch must extend above the stripper plate. How much higher? It must be exactly the height required for the embossing, and must be within the allowable embossing height accuracy range.

When the mold opens and closes, and the mold is not under any force, the punch for the raised part must be shorter than the stripper plate and retracted into the stripper plate; otherwise, the stripping stroke must be increased.

When punching raised parts with a compound mold, the stripper plate must first press down on the material when the mold is released, and the pressing force must be sufficient before punching the raised part; otherwise, the product may be deformed, or the raised part dimensions may be unstable.

★Spring Compression and Calculation

Flat wire springs are generally classified by color: brown, green, red, blue, and yellow, with force decreasing in that order. Different colors indicate different strengths and compression levels.

Before die assembly, the spring compression must be calculated to ensure it is appropriate. This prevents problems such as die failure or explosion during trial runs.

★Determining the Blanking Die Clearance: The blanking clearance is generally determined using empirical formulas and charts.

The following is theoretical knowledge from textbooks, mainly based on ensuring the fusion of upper and lower cracks to obtain a good cross-section.

Based on the relationship of triangle ABC, the clearance value c can be obtained as:

c = (t – h0) tanβ = t (1-h0/t) tanβ
Where, h0-- the die cutting depth; β-- the angle between the direction of maximum shear stress and the vertical direction.

Therefore, the main factors affecting the clearance value are the material properties and the material thickness. The harder or thicker the material, the larger the clearance value.

★The Entire Process of Stamping Die Development

How are stamping dies manufactured step by step?

★What is a punch? How is punch length calculated?

How is punch length calculated?

First, let's examine what a punch is and what role it plays in a stamping die.

The length of the punch for stepping is equal to: the thickness of the clamping plate + the thickness of the stop plate + the thickness of the stripper plate + the step height.

These are just fixed rules; actual application depends on the situation. They won't be explained in detail here, but you'll understand them naturally as you gain more knowledge about stamping dies.

★Composite Dies, What are Composite Dies?

Due to the different combinations of processes in compound molds, the ejector devices also vary. I'll share some common compound mold structures with you when I have time.

Continuous dies are generally used for upward forming, upward bending, upward embossing, upward dotting, and upward cornering, and often employ a compound die structure.

★When using a compound die to punch embossing, must the punch extend above the stripper plate?

Today, I received a question from a student: When using a compound die to punch embossing, must the punch extend above the stripper plate?

The answer is yes, otherwise how can you punch embossing?

I suggest this student review what a compound die is and how to calculate the punch length. Once you understand these concepts, you'll naturally understand how to answer this question.

When using a compound die structure to punch embossing, the punch length is equal to: clamping plate thickness + stop plate thickness + stripper plate thickness + embossing height.

★Materials and Functions of Stamping Die Templates

General stamping dies consist of:
* Upper and lower support plates, upper and lower pads, and upper and lower die bases: These are typically made of "soft materials" such as A3 or Q235, serving to support the entire die, facilitate die setup, and facilitate blanking.

* Upper and lower die plates: These plates fix the cutting edge, insert block, insert, and ejector pin. External positioning, internal positioning, floating guide pins, dual-purpose pins, guide plates, and floating blocks are also fixed to the lower die plate. The lower die plate must have a hardness of approximately HRC58-62; too low a hardness will affect the stamping quality. The thickness is generally 25-40mm. Some cutting edges are directly cut into the die plate, meaning the cutting edge is directly carved into the die plate. However, if the cutting edge is chipped, broken, worn, or has burrs, it is difficult to repair the die. Another method is to carve an insert block (commonly called the "lower die cutting edge"), and then insert the lower die cutting edge into the lower die plate. The height must be the same as the lower template, with an error within ±1-2 mm, ideally within ±0.005 mm. This is generally achievable by grinding machine operators or fitters. Too much error will leave marks on the product (mold marks).

Upper and lower backing plates are typically made of Cr12 stainless steel. The thickness of the upper and lower backing plates varies depending on the need and punching force. If fewer holes are punched, the backing plates can be thinner (8-10 mm). If more holes are punched, they need to be thicker, generally around 17-20 mm. The lower backing plate mainly houses blanking holes, spring through holes, screw through holes, and guide post vents.

Upper and lower clamping plates primarily serve to fix the punch, die, and guide post. A thickness of 17-20 mm is generally sufficient. The material hardness of the stamping die clamping plates does not generally need to be particularly high; softer materials are fine. However, materials that are too soft are also undesirable, as they may pull the punch holder directly into the clamping plate, damaging it. Therefore, when designing stamping dies, the die structure, die material selection, press tonnage, and blanking clearance must be considered in relation to the blanking process of the workpiece to be stamped. This will minimize burrs on the finished workpiece and extend the die's lifespan.

Stop plates and stripper plates are used. Cr12 can be used for the stop plate, but the stripper plate must be made of a hard material such as Cr12Mov. The stop plate and stripper plate are locked together using M6 or M8 screws and pins. The stop plate mainly has through holes, such as punch through holes and guide post through holes. The stripper plate mainly serves to remove, press, and guide the punch. Generally, we use the stripper plate to guide the punch, guide post, and punch. In aluminum production, aluminum shavings easily jump into the stripper plate, causing damage to the punch, jamming the punch, breaking it, or pulling it out of the stripper plate. Therefore, stop plates are necessary to guide the punch, and the stripper plate is appropriately enlarged by 10-20 shavings on one side; alternatively, the stripper plate can be made in two sections, with the upper section for guidance and the lower section also enlarged by 10-20 shavings on one side. The stop plate thickness is generally 8-17 mm, depending on the number of punches and the amount of force required; the stripper plate thickness is generally 20-25 mm.

The die, also called a punch or cutting edge, is used to punch away, cut away, cut, puncture, or stretch excess material. Examples include: drawing punches, bending punches, slide cutters, embossing punches, drawing punches, and riveting punches for riveting dies, etc. The materials for dies and punches require high hardness. Commonly used die and punch materials include: Cr12Mo1v1, Cr12Mov, Skd-51, Skd-11, W6Mo5Cr4V2 (tungsten carbide), etc.

Technical Terminology Explanation:

**Digging:** A term commonly used in die making, referring to the wire cutting edge. For example: cutting the cutting edge, cutting the insert, etc.

**Soft Material:** In stamping dies, this refers to die steel with a hardness of around HRC35, such as 45# steel, A3, Q235, etc. You can easily dent this material by tapping it with something slightly harder; it's very soft, hence the term "soft material." Because of its good shock resistance, it's generally used to make the upper and lower support plates, upper and lower pads, and upper and lower die bases of stamping dies.

Hardened materials: In stamping dies, this refers to die steel with a hardness (after heat treatment) of approximately HRC 58-62 or higher, such as Cr12, Cr12Mo1v1, Cr12Mov, Skd-51, Skd-11, and W6Mo5Cr4V2 (tungsten steel). These steels have very high hardness (but are also relatively brittle; a slight mistake could easily chip them off). They are generally used for the cutting edges, punches, or other parts requiring high hardness in stamping dies.

★ Three-view drawings of stamping dies
Do you understand the three-view drawings of stamping dies? Whether you're a stamping die fitter, a stamping die designer, or an CNC operator, CNC programmer, or someone working with grinding machines or milling machines, anything related to machining requires the ability to read and understand drawings. This is essential. If you can't even understand the drawings, how can you machine parts?

View: A geometric pattern obtained by observing an object from different directions.

For example, when an object is placed in front of you:

1. Viewing it from the front, the resulting geometric shape is called the front view; viewing it from the back, the resulting geometric shape is called the rear view.

2. Viewing it from the left, the resulting geometric shape is called the left view; viewing it from the right, the resulting geometric shape is called the right view.

3. Viewing it from top to bottom, the resulting geometric shape is called the top view; viewing it from bottom to top, the resulting geometric shape is called the bottom view.

4. To make the diagram more accurate, easier to understand, and more readily comprehended, sometimes sectional views, full sectional views, half sectional views, and cross-sectional views are also needed. A sectional view is the view you see when the object is cut open; a full sectional view is the view obtained by completely cutting the object open; a half sectional view is the geometric shape obtained by cutting the object in half (not completely); a cross-sectional view is like imagining the object breaking at a certain point, and then graphically representing the view you would see after the break.

Hey, I wonder if my explanation has confused you? Below is a diagram; looking at it should help you understand: Can you draw the geometric solid represented by these views using 3D drawing methods?

Let's talk about three-view drawings.

Basic rules of three-view drawings: Length aligned, width aligned, height equal.

Length aligned-The lengths of the front view and top view are aligned.

Width equal-The widths of the top view, left view, and right view are equal.

Height aligned-The heights of the front view, left view, and right view are aligned (equal).

The following information is from another source; I hope it will be helpful to your learning.

Actually, you don't need to understand these concepts thoroughly; a general understanding is enough. After all, this is theoretical knowledge, and theoretical knowledge is static; knowing too much of it is useless without practical application. The most important thing is practice and practical ability-being able to understand and interpret drawings, being able to represent a geometric object using views, and having others clearly understand what you are trying to express after looking at your drawings. That's already very good. Mold design involves expressing one's ideas through drawings. Others then manufacture the parts based on these drawings. Finally, a fitter assembles the mold and produces a qualified sample.

★Common Materials for Stamping Dies
Common stamping materials for stamping dies (also called hardware molds) include:

Aluminum: Aluminum is commonly used for exterior parts, such as keyboards for laptops or netbooks, and other accessories.

Galvanized Steel Sheet: This is cold-rolled steel sheet coated with a zinc layer. Galvanized steel sheets include SECC and SGCC, which are rust-proof and corrosion-resistant. They are relatively expensive. Common thicknesses range from 0.4 to 3.2 mm. They are characterized by excellent paintability, good fingerprint resistance, good corrosion resistance, and maintain the machinability of cold-rolled steel. SGCC material with a thickness of 0.80 mm is commonly used for chassis and bottom covers. It has medium hardness, slightly harder than aluminum but softer than stainless steel. SGCC material is relatively hard and has poor tensile properties. If this material is used for stretching, the die and punch must be polished to a very high shine; otherwise, it is prone to cracking or micro-cracks.

Stainless steel: It can be used to produce various sizes of springs and external parts. For example, the springs for various interfaces on the back of desktop computer cases are made of stainless steel and produced using stamping dies. Stainless steel is relatively hard, and sometimes when dies cannot find shims for maintenance, stainless steel can be used as a temporary solution. The punches and cutting edges of dies used for stamping stainless steel require frequent maintenance to ensure smooth production. Otherwise, frequent die repairs are necessary.

Generally, shims need to be spot-welded onto the part using a spot welding machine; otherwise, they will fall off during the next die removal, causing problems. Some factories do not allow the use of shims; in this case, they can be welded on, and then ground to the required dimensions using a grinder.

Commonly used stainless steel materials include SUS301 and SUS304. SUS200 series (including 201, 202, etc.)

SUS300 series (including 301, 304, 310S, 321, 316L, etc.)

SUS400 series (including 409, 410, 420J1, 420J2, 430, 436L, 444, etc.)

Tinplate: Tinplate? A little confusing, right? When the foreman at the factory called it tinplate, I mistakenly thought it was "má guī tī" (麻口铁). Wrong. Actually, I'm not sure either; the pronunciation is the same. So let's just call it má guī tī! Má guī tī has good ductility, low hardness, and is relatively soft. It's generally suitable for complex curved surface stretching because it's less prone to cracking. For example, top covers, and some small spring clips.

Tinplate, where Sn is the plating, is also called tin-plated iron. Tinplate is a common name for electroplated tin-coated thin steel sheet, abbreviated as SPTE. It refers to cold-rolled low-carbon thin steel sheet or strip plated with commercially pure tin on both sides. Tin mainly serves to prevent corrosion and rust. It combines the strength and formability of steel with the corrosion resistance, solderability, and aesthetic appearance of tin into one material, possessing characteristics such as corrosion resistance, non-toxicity, high strength, and good ductility.

★What is pitch positioning?
What is pitch? What does pitch positioning mean? Pitch, as the name suggests, refers to control or regulation. Pitch positioning means positioning by controlling the distance. It controls the feeding distance to prevent overfeeding, misfeeding, damage to the mold, or production of defective products.

In stamping dies, pitch positioning is generally used in progressive dies.

Those who know might say, "Of course, engineering dies don't use pitch positioning!" Hehe.

Why is pitch positioning only used in progressive dies, while engineering dies generally don't?

That's because engineering dies typically produce sheet metal of similar size and dimensions, which is directly placed into the engineering die for processing. Otherwise, it wouldn't be called an "engineering die." Of course, some engineering dies have automatic feeding systems; these usually have pre-set feeders that automatically deliver the material after the press strikes.

Progressive dies generally have dedicated automatic feeders. Otherwise, how could they process the material? Manual feeding is problematic because inaccurate feeding can lead to a high scrap rate, a risk avoided by automatic feeders. Furthermore, only small factories typically use manual feeding; larger factories usually have automatic feeders. The operator simply places the material onto the feeder according to requirements and sets the settings.

However, automatic feeders aren't always perfectly accurate and can sometimes have small errors. This is where pitch positioning plays a crucial role. Some say, "Pitch positioning is the distance between two positioning pins." Is that correct? Actually, this statement isn't wrong; theoretically, it is. But what is the distance between the two positioning pins? How is it calculated? Haha, this question is too profound. You should ask a master craftsman who specializes in hardware mold design.

The blue area is called the strip material. Then there are two red circles; these are the locations of the cutting tool punches. I won't talk about the cutting tool punches here; I'll discuss them in a future blog post. This time, we're mainly discussing pitch positioning. Okay, let's continue. Here's a pitch positioning block; let's just call it pitch positioning for now, because that's what we often say in mold making, like, "Where did you put the pitch positioning block?" "Make a pitch positioning block." Here, pitch positioning refers to this entry block.

Pitch positioning blocks are usually installed in the lower mold (haha, I'm repeating myself again; if not the lower mold, where else would you install it? Stupid.). It's where the strip material initially enters. The strip material first enters from the very beginning of the progressive die, then two holes (positioning holes) are punched. Next, it passes through the cutting tool area (what is a cutting tool? I'll explain later.). After passing the cutting tool, the strip material is trimmed here, cutting off a portion. Then, the pitch positioning block blocks the strip material to prevent misfeeding.

Notice the two red circles? What are they? Why are they circled? Think about it.

In the first red circle, there's a small notch. Why leave a notch there instead of cutting it at a 90° right angle? Think about it.

Because what's behind it? It's for pitch positioning. Pitch positioning is usually done at a right angle. Imagine what would happen if the cut edge here was also a right angle?

The cut edge is a right angle, so the punch must also be made into a right angle, because a right angle is a sharp angle, and the material used for punches is generally very brittle, even though it has high hardness (the higher the hardness, the more brittle it is; I don't know if this is correct, so please don't mislead you!). It's very brittle and easily breaks. After many production runs, that small sharp angle might disappear. At this point, will the cut still be 90 degrees? Even if it is 90 degrees, there will be a large burr, making it inaccurate at the pitch positioning point, resulting in errors in the finished product. Now you know why there's a small notch there?

Does the point where the pitch positioning contacts the material need to retain a sharp angle?

Of course it does! Other unused areas can be chamfered to prevent scratches. But this point must never be chamfered. One cut will negate the pitch positioning function, requiring it to be re-welded back together. After grinding, a right angle is formed. If you find it too sharp, you can lightly scrape it with a file, but be careful not to make too large a cut.

Because feeders generally have a high feeding force, and the cutting edge usually only cuts off a narrow section, if the angle is beveled here, and the material is thin, the material might directly bypass the pitch positioning and rush into the mold. In this case, the pitch positioning is ineffective.

Generally, larger progressive dies use a dual-purpose pin + pitch positioning insert block. That is, there is a dedicated insert block at the pitch positioning point, installed at the cutter and edge trimming area. However, this structure is not suitable for smaller molds and thinner materials. Think about why?

Generally, when the mold is small and the material is thin, a pressure plate is used instead of a dual-purpose pin. Because the material is thinner, feeding with a pressure plate is relatively easier, while a dual-purpose pin is more cumbersome. In this situation, you can generally use... A pressure plate plus a pitch positioning block, or even better, no pitch positioning block at all. Why use a pitch positioning block when you already have a pressure plate? The designer must have eaten dog shit to design such a terrible mold! Hahaha.

If you design a small mold using a pressure plate plus a pitch positioning block, the fitter will definitely curse you like the one above when assembling the mold. Why do I know this so clearly? Because there was a stupid designer who designed such a terrible mold, and our fitter colleagues cursed him and laughed at him behind his back. Hehe.

How do you use a pressure plate for pitch positioning? It's like this. Suppose the material width is 10mm, and the edge is cut off... Two millimeters, so the distance between the first pair of pressure plates can be designed to be 10 millimeters (of course, clearance is necessary, don't be so silly!). Two millimeters are cut off at the cutting edge, so the distance between the second pair of pressure plates (after cutting) can be designed to be 8 millimeters. This allows for pitch positioning.

★Analysis of the causes of scrap jumping in stamping dies, and how to fix it.

What is scrap jumping? What is chip jumping? Some students may not understand, so let me explain.

Scrap jumping and chip jumping are basically the same thing; it means the scrap jumps upwards, onto the lower die plate, or to other places. In short, the scrap jumps out from the cutting edge.

The punch cuts off the excess scrap. Then, due to errors by mold repair personnel, designers, or production line workers, some scrap material that had already been removed might jump out from the lower die cutter edge again. Imagine how dangerous this is!

At best, several products will be scrapped; at worst, the mold might be damaged; and in very serious cases, people could be injured. It's truly terrifying. This is the nature of mold making; many people have lost hands or become disabled due to carelessness while making molds. Unless you're in mold design or something else, danger is lurking everywhere you deal with molds!

Getting back to the point, let's analyze the causes of scrap jumping from stamping dies and how to prevent it.

(I) Causes of Scrap Jumping (Scrap Chip Jumping) Reasons:

1. The shape of the blanking scrap or blanked part: If the shape is too simple or the weight too light, it is easily carried up by the punch.

2. Magnetic forces: The punch or cutting edge may be magnetic, either naturally or due to changes in magnetism caused by grinding or impact. These factors easily attract scrap, especially ferrous materials such as tinplate, SECC, and SGCC. Mold parts made from these materials must be demagnetized; otherwise, the mold will constantly produce chips, requiring frequent repairs – a very troublesome process.

3. The impact of the blanking clearance: Too small or too large a clearance may cause burrs to return to the mold surface with the punch, resulting in insufficient machining accuracy. Influence of errors, etc.

4. The effect of punching speed: Excessive speed may cause the punch, the inner wall of the cutting edge, and the scrap to form a piston, resulting in vacuum suction. This means the punch sucks the scrap out of the lower die cutting edge. To prevent this, you can have the designer cut a small hole in the middle of the punch and add corresponding grooves to the backing plate to allow airflow and prevent vacuum suction. Alternatively, make the cutting edges of the punch not on a single plane; this reduces the likelihood of suction. See the diagram for details.

5. Improper selection and amount of cutting oil: Adding too much oil or oil that is too viscous can cause scrap to adhere to the punch and not fall off, leading to chipping.

6. The sharpness of the die cutting edges. The degree of sharpness is too high; too much shine and few burrs result in low friction with the cutting edge and die, making it easy for the punch to be sucked in. In this case, you'll have to find other ways to repair the mold; you can't just work on the punch itself.

7. Punch length affects the process. Generally, the "punch" length for punching is equal to: the thickness of the clamping plate + the thickness of the stop plate + the thickness of the stripper plate + the material thickness + (1-2) millimeters. As long as this length is met, it's fine. However, if it's too long, the punch will start punching before the material is fully pressed down, easily causing wear on the punch cutting edge. If it's too short, the scrap material won't be completely punched into the slope or small step below the cutting edge, and it's easy for it to jump up.

8. The lower die cutting edge... The reasons are as follows: 1. The lower die cutting edge usually has a slope or step, generally between 3 and 5 degrees, depending on actual needs and die strength. Excessive grinding increases the punching clearance, leading to chip skipping.

9. Other reasons, such as foreign objects adhering to the material and being carried into the die.

10. If the punch is large and strong enough, a hole can be drilled in the middle, and a stop screw can be locked at the back of the punch. The stop screw, spring, and ejector pin will push the scrap material down. The ejector pin should protrude one or two millimeters above the punch surface; too long, and it may deform the product.

11. Alternatively, a small amount of urethane glue can be applied to the front of the punch with 502 glue, or a small spot can be welded. Uploading requires a sufficiently large punch and good welding techniques; otherwise, the punch will be damaged, affecting its strength.

★Product Quality Analysis of Stamping Die Drawing Parts
Product Quality Analysis of Stamping Die Drawing Parts
During the product drawing process, the main problems that may occur in drawn parts are: wrinkling, cracking, uneven thickness, surface scratches, shape distortion, and springback. Among these phenomena, wrinkling and cracking have the greatest impact on product quality. Products with these two problems will definitely not be delivered and must be corrected. Products with these two problems generally have to be scrapped, and customers will not accept them.

I. Wrinkling During the drawing process, the surrounding edges of the material, due to tangential stress... Excessive stress can cause material instability, resulting in uneven wrinkles along the tangential edge of the product, a condition known as wrinkling.

Severe wrinkling can also make it difficult for the material to pass through the gap between the die and punch during stretching, increasing the tensile deformation force and even leading to tearing.

The occurrence of instability depends on both the magnitude of the tangential stress at the material's edge and the thickness of the stretched part.

Generally, nitrogen springs or urethane rubber are better for stretching dies, as they are less prone to wrinkling and cracking. Why? Because nitrogen springs or urethane rubber generally provide more even force, avoiding uneven force distribution.

Nitrogen springs are better than urethane rubber because nitrogen springs have a stronger force... Nitrogen springs are available in large quantities and have a very consistent strength, but they are many times more expensive than urethane, making them unaffordable for many factories. Generally, only larger factories can afford to use nitrogen springs.

Urethane shrinks over time, losing its initial strength and requiring replacement. However, it is much cheaper than nitrogen springs.

To prevent wrinkling, pressure rings, sometimes called pressure ribs, are used. These are raised ribs placed around the material without affecting subsequent processes, holding the material in place. This results in a fuller, more even product after stretching and prevents wrinkling. The blank holder force needs to be adjusted during trial molding. The initial design is rarely perfect, and adjustments to the height of the blank holder ribs are necessary based on the produced product. Excessive blank holder force increases friction between the material, the die, and the blank holder ring, leading to thinning of the material wall and even tearing. Insufficient blank holder force fails to effectively prevent wrinkling.

The second problem is tearing, a common issue encountered during the stretching process.

When the tensile stress on the cylinder wall exceeds the material's strength limit, the product will tear. The tear typically appears slightly above the punch radius on the cylinder wall.

Factors affecting tearing include: the material's tensile properties, material... The diameter and thickness of the material, the drawing coefficient, the fillet radius of the die and punch, the blank holder force, and the coefficient of friction, etc.

If the fillet radius of the die and punch is too small or too sharp, it is easy to tear the product. Common die repair methods include increasing the fillet radius, smoothing the fillet area, and polishing it. If all else fails, applying oil during production, especially drawing oil, is very effective.

When designing stamping dies, try to increase the fillet radius as much as possible, within the limits of customer product requirements. Avoid making them too sharp. Some designers lack understanding and create drawing dies that crack severely during trial runs, making die repairs incredibly difficult and exhausting for the fitter.

During drawing, use... Proper lubrication is essential for the smooth progress of the drawing process and improves the thinning of the cylinder wall. However, it is crucial to note that lubricant should only be applied to the working surface of the die cavity. The contact surface between the punch and the material should never be lubricated, as this creates beneficial friction between the punch and the blank surface, preventing material slippage, tearing, and thinning.

★What technical skills and processing equipment are required for repairing stamping dies? The various parts of a stamping die must first undergo these procedures:

First, the material must be cut. Without cutting the material, how can the next step of processing proceed? Cutting refers to rough machining. Generally, a die template must first be roughly planed flat on a planer, and then roughly ground on a large surface grinder (also called a large grinding machine). Rough machining is performed, leaving a certain allowance (generally 50 mm, with a precision requirement of ±10 mm). Then, parts requiring heat treatment are sent for heat treatment. After heat treatment, they undergo precision machining on a large grinding machine. At this stage, higher precision is required; for example, if the template thickness is 25.00 mm, the precision requirement must be within ±0.01 mm. This depends on the purpose of the template; generally, a difference of one or two mm is not significant, as long as the finished product does not have mold marks.

After grinding, the parts are sent for threading holes, then wire cutting, followed by milling, CNC machining, etc.

For small parts, the process is as follows: depending on the size of the part, it is sawed with a saw or milled... After roughing on a milling machine, the surface is ground, excess material is removed, and once it's roughly finished, it's either wire-cut or CNC (high-speed milling) machining, depending on the needs. Electrical discharge machining (EDM) is used if necessary. After that, quality assurance measurement is performed.

In general, planers, lathes, milling machines, drilling machines, and grinding machines are essential tools for mold fitters. However, larger factories nowadays rarely use planers or lathes because specialized personnel handle these processes, so you don't need to worry about them. Aside from planers and lathes, what other machining equipment must fitters master?

Since making a stamping die requires so much machining equipment, what about die repair? The die is... Why does it need repair?

Because it's broken and can't produce products. Why did it break? Because of flawed design, prolonged mold production time, technical issues with the mold repair personnel, or carelessness by production line workers, etc.

What does mold repair mainly involve fixing?

Fix what's broken. For example, if the ejector isn't ejecting material, it might be due to insufficient spring force, an unreasonable design of the ejector component, etc. In this case, it might require replacing or adding springs, improving the ejector structure, adding ejector pins, etc. This requires drilling on a drilling machine or countersunk drilling on a milling machine. Welding might also be needed, requiring knowledge of arc welding machines and argon arc welding. After welding, grinding and milling might also be required.

Okay, enough said. In general, the skills a stamping die fitter/repairman needs include:

1. A thorough understanding of the working principles of various dies and their machining precision requirements. If you're responsible for a set of stamping dies, you first need to fully understand its structure, working principles, and design concepts. You must be familiar with the function and performance of each part so that you can quickly pinpoint the problem and repair specific areas when the die malfunctions or breaks during production. Each die has a different structure and the designer's approach, so the repair methods are different for each set, though they are largely similar. With experience, you can confidently say "no problem" with any die you handle, because you can overcome any issue-it's just a matter of time and effort. However, even with extensive experience, you won't be entirely confident. Die technology develops rapidly; new techniques and ideas will emerge quickly. A repair method used yesterday might not be as effective today. Hehe, that's a bit of an exaggeration, don't let it discourage you from learning about dies!

2. Be proficient in operating grinding machines, milling machines, drilling machines, and TIG welding machines. The parts processed should meet the precision requirements of the mold. Planing and lathe skills are rarely needed, and not knowing them isn't a big deal. While these skills used to be essential, they are no longer required due to rapid technological advancements. A basic understanding of grinding drill bits and milling cutters is also necessary, as these are sometimes required for mold repair. If you don't know how, you'll be stuck and have to ask for help.

3. Do you know what EDM, wire EDM, and CNC machining do? What are their respective machining precision levels? When should you use which one? You need to be completely clear on this. This will allow you to choose flexibly during mold repair, saving time and improving efficiency.

In short, that's about it. Once you understand the working principles of molds, you'll be fearless. If a mold breaks, you'll immediately know where the problem might be and what needs to be changed.

For designers, you need to be proficient in drafting software and solid modeling, such as CAD, UG, Pro/E, 3DMAX, Mastercam, etc., depending on the factory's requirements. Being able to design the mold is sufficient! CAD can be used to design relatively simple molds, while more complex molds require 3D modeling. Solid modeling is more intuitive and reduces errors. Even with strong spatial imagination, relying solely on CAD for conceptual design doesn't guarantee a complete understanding of complex mold structures, leading to mistakes, omissions, and structural errors, increasing mold processing time and delivery time, wasting time and resources. For fitters, some knowledge of drafting software is also necessary, such as checking straight line lengths and part widths. This is crucial for mold repair, as it's essential for machining and repair without knowing part dimensions.

★The Role of the Stripper Plate Pressure Groove in Progressive Dies Most mold stripper plates, such as engineering molds, don't have pressure grooves. Why then do progressive dies require them? Why don't engineering dies need pressure grooves? Haha, do you understand now?

Why don't engineering dies need pressure grooves? This is because the materials stamped by engineering dies are generally thicker, rougher, and have lower precision. They don't require the long strip of material that progressive dies can press. Also, engineering dies are smaller, with shorter die plates, and the required dimensional accuracy is not as high. They are also easier to repair and adjust. Therefore, engineering dies generally only need limit pins and don't need pressure grooves. Progressive dies, on the other hand, need to achieve mass production, and the product precision is higher than that of engineering dies. Therefore, the precision requirements for the die are relatively higher, and pressure grooves are one way to improve die precision. Therefore, progressive dies generally use pressure grooves in conjunction with limit pins to control the gap of the product strip in the die.

Why do progressive dies need to be designed with pressure grooves? Because when the stripper plate of a progressive die contacts and presses down on the material, strong pressure doesn't necessarily mean it completely holds the material in place. Therefore, the surface of the stripper plate that contacts the lower mold plate of a progressive die usually has a pressure groove with a depth of 0.05mm to 0.08mm (adjustable according to the material thickness), commonly known as "pre-pressing." The width is slightly wider than the strip material to ensure all the material is pressed inside. This ensures a uniform gap between the strip material and the die during cutting, allowing the die to fully hold the material in place and preventing uneven pressure that could cause wear on the punch and cutting edges, or uneven finish.

Note: Because the pressure groove works in conjunction with the locating pins to control the gap of the strip material in the die, and the stripper plate has a pressure groove, the pre-pressing depth should also be considered when designing the locating pins (sometimes called height-limiting pins, haha). This reduces the adjustment time for the fitter during die assembly and speeds up the die-making process.

For example: If the product material thickness is 0.20mm and the stripper plate pressure groove can be designed to be 0.05mm, then the height of the limiting post on the lower template can be designed as: lower template thickness + (0.20mm - 0.05mm). If the lower template thickness is 25.00mm, then the height of the limiting post on the lower template can be designed as: 25.00mm + (0.20mm - 0.05mm) - 0.03mm (for strong pressure) = 25.12mm. This is sufficient; leave about 0.03mm for the strong pressure. If the limiting post height is designed to be 25.15mm, then there will be no strong pressure, which is unreasonable. It's best to leave a little strong pressure, 0.03mm is enough; don't design it too rigidly.

★What is the purpose of the progressive die foot support plate?

What is the purpose of the progressive die foot support plate?

Foot supports can be divided into lower feet and upper feet; support plates can be divided into lower support plates and upper support plates.

The main functions of the foot support plate in progressive dies are: to support and fix the die, provide pressure resistance and shock absorption, extend die life, increase die height, and facilitate die setup (i.e., mounting the die onto the press). The lower foot and lower support plate also facilitate waste removal.

What is the purpose of the foot support plate in progressive dies? Actually, these are basically useless; it's best to avoid them if possible, since there's also the die base.

When die setup is convenient, the upper support plate and upper foot can be omitted. In other words, the upper foot and upper support plate are optional. As long as die setup is convenient, the die-setting slot can be designed on the die base, saving materials, reducing unnecessary waste, and saving company expenses.

However, note: For dies that require blanking, be careful when neglecting the lower support plate and lower foot. The lower foot and lower support plate also facilitate waste removal. Don't forget this! If you make such a mistake and the die has nowhere to blank, you'll be laughed at.

Provided that blanking is not affected or unnecessary, mold setup is convenient, and other mold performance is not compromised, the lower support foot and lower support plate can be omitted. Since they are not needed, they can be omitted.

★The Function of the Stripper Plate in a Stamping Die
The stripper plate is the common name for the stripper plate. The upper die stripper plate is abbreviated as PSU. Above the stripper plate is the stop plate (PPS), then the clamping plate (PHU), the backing plate, etc. Of course, there are not only upper stripper plates, but also lower stripper plates, etc.

What is a stripper plate? What is the function of the stripper plate in a stamping die?

"Stripping," of course, does not mean stripping away the surface. Understanding stripping away the surface is not wrong, hehe. Here, "脱" (tuō) indeed refers to removing or separating the material or product from the mold, commonly known as "脱料" (tuōliào). When the product is stuck in the mold and cannot be removed, it's called "不脱料" (bùtuōliào). When repairing mold problems, the issue of "不脱料" is frequently encountered, such as "The xx mold is not removing material, please go and repair it!", meaning the product is stuck to the mold and cannot be removed.

What is the function of the stamping die release plate? Its primary function is, of course, release-removing the product from the mold. But does it have any other functions? What does it look like when the mold is closed?

Haha, you've got it? It's used to work with the lower die plate. And what is the purpose of working with the lower die plate? It's for pressing the material. Got it?

In summary, the stamping die release plate has two functions: first, release-separating the product; second, press-holding the material in place for bending, punching, and other processes.

You could also say that the functions of the stamping die release plate are release and pressing. This is also acceptable; it's clear and easy to understand.

★What components are generally required to form a relatively complete stamping die?
The components generally required to form a relatively complete stamping die include: template, insert block, and standard parts, etc.

Template includes: upper and lower support plates, upper and lower pads, upper and lower die bases, upper and lower templates, upper and lower backing plates, upper and lower clamping plates, stop plates, stripper plates, dies, punches, or cutting edges, etc.

Insert blocks (upper die): clamping plate insert block, stripper plate insert block, punch, etc.

Insert blocks (lower die): lower die insert block, lower die cutting edge, float block, positioning insert, etc.

Standard parts: springs, hexagonal screws, stop screws, wire springs, equal-height sleeves, guide pillars, guide bushings, equal-height sleeve washers, dual-purpose pins, ejector pins, etc.

Non-standard parts: external positioning, internal positioning, pitch positioning, external limit pins, internal limit pins, etc.

info-750-750

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