Analysis of common problems and solutions of stamping dies

1. Punch rough edge
(1) Cause: A. Blade wear; B. The gap is too large and the effect is not obvious after trimming the blade; C. Blade angle collapse; D. Unreasonable up and down deviation or looseness of clearance; E. Upper and lower dislocation.
(2) Countermeasures: A. Study and repair the cutting edge; B. Control the machining accuracy of the male and female dies or modify the design clearance; C. Study and repair the blade; D. Adjust the blanking clearance to confirm the wear of the template hole or the processing accuracy of the molded part; E. Replace the guide part or reassemble the mold.
2. Chip jumping and crushing
(1) Cause: A. The clearance is too large; B. Improper feeding; C. The pressing oil drops are too fast and sticky; D. The mold is not demagnetized; E. The punch is worn and chips are pressed on the punch; F. The punch is too short and the length inserted into the female die is insufficient; G. The material is hard and the punching shape is simple; H. Emergency measures.
(2) Countermeasures: A. Control the machining accuracy of male and female dies or modify the design clearance; B. Trim the material belt and clean the mold in time when it is sent to the proper position; C. Control the amount of oil dripping of the stamping oil, or change the oil type to reduce the viscosity; D The mold must be demagnetized after research and repair (more attention should be paid to punching iron); E. Study and repair the punch blade; F. Adjust the length of the male die edge into the female die; G. Replace materials and modify design. Insert the punch edge into the end face, install and eject or repair the inclined plane or arc (pay attention to the direction). Reduce the fitting area between the end face of the punch edge and the scrap; H. Reduce the sharpness of the concave die edge, reduce the amount of research on the concave die edge, increase the surface roughness (coating) of the straight edge of the concave die, and use a vacuum cleaner to absorb waste. Reduce the impact speed and chip jumping.
3. Chip blocking
(1) Cause: A. The leakage hole is too small; B. The leakage hole is too large, and the scraps roll; C. The blade is worn and the rough edge is large; D. The pressing oil drops are too fast and sticky; E. The surface of the straight edge of the die is rough, and the powder chips are sintered and attached to the edge; F. The material is soft; G. Emergency measures.
(2) Countermeasures: A. Modify the leakage hole; B. Modify the leakage hole; C. Blade trimming edge; D. Control the amount of oil dripping and change the oil type; E. Surface treatment, polishing and attention shall be paid to reducing surface roughness during processing; Change the material, F. Modify the blanking clearance; G. Trim the slope or arc (pay attention to the direction) on the end face of the punch edge, use a vacuum cleaner and add air at the blanking hole of the base plate.
4. Deviation size variation of blanking
(1) Cause: A. The tool edge of the male and female die is worn, resulting in burr (the shape is too large, and the inner hole is too small); B. Improper design size and clearance, poor machining accuracy; C. The blanking position punch and die insert are offset and the gap is uneven; D. The guide pin is worn and the pin diameter is insufficient; E. The guide element is worn; F. Improper adjustment of feeding distance, pressing and loosening of feeder; G. Improper adjustment of mold closing height; H. The material pressing position of the stripping insert is worn, and there is no material pressing (strong pressure) function (small punching caused by material pulling and turning); I. The unloading insert is too deeply pressed and the punching is too large; J. Mechanical property variation of stamping materials (unstable strength elongation); K. During punching, the punching force pulls the material and causes dimensional variation.
(2) Countermeasures: A. Study and repair the cutting edge; B. Modify the design and control the machining accuracy; C. Adjust its position accuracy and blanking clearance; D. Replace the guide pin; E. Replace the guide post and guide sleeve; F. Readjust the feeder; G. Readjust the closing height; H. Grind or replace the stripping insert, increase the strong pressure function, and adjust the pressing; I. Reduce the depth of strong pressure; J. Replace materials and control the quality of incoming materials; K. Trim the slope or arc (pay attention to the direction) at the end face of the punch edge to improve the stress condition during punching. When permitted, the blanking part is located on the unloading insert and equipped with a guide function.
5. Material jamming (1) cause: A. Improper adjustment of feeding distance, pressing and loosening of feeder; B. The delivery distance changes during production; C. Feeder failure; D. The material is curved, the width is out of tolerance, and the burr is large; E、
Abnormal die stamping and sickle bending; F. The hole diameter of the guide material is insufficient, and the upper die pulls the material; G. Unsmooth material stripping up and down at the bending or tearing position; H. The stripper function of the guide plate is improperly set, and the material belt is attached; I. The material is thin and warped during feeding; J. The mold is improperly erected and has a large deviation from the perpendicularity of the feeder.
(2) Countermeasures: A. readjustment; B. Readjust; C. Adjustment and maintenance; D. Replace materials and control the quality of incoming materials; E. Eliminate the sickle bend of the material belt; F. Study and repair the convex and concave die of the punching guide hole; G. Adjust the force of the stripping spring, etc; H. Modify the material guide and put on the material belt; I. The upper and lower pressing and the upper and lower extruding safety switches are added between the feeder and the mold; J. Erect the mold again.
6. Material belt sickle bending
(1) Cause: A. Stamping burr (especially on the carrier); B. Material burr, no trimming of the mold; C. The depth of the punch is improper (too deep or too shallow); D. The punch is crushed and there are scraps in the mold; E. Local pressing is too deep or local damage is caused by pressing; F. Mold design.
(2) Countermeasures: A. Study and repair the cutting edge; B. Replace the material and add the trimming device to the mold; C. Re-adjust the depth of the punch; D. Clean the mold and solve the problems of chip jumping and crushing; E. Check and adjust the height and size of each stripping and die insert to be correct, and repair the damage position; F. The bending mechanism is used for adjustment.
7. Punch fracture and edge collapse
(1) Cause: A. It is caused by chip jumping, chip material blocking, clamping, etc; B. Improper feeding, cutting half of the material; C. The punch strength is insufficient; D. The big and small punch are too close to each other, and the material is pulled during punching and cutting, causing the small punch to break; E. The part of the punch and female die is too sharp; F. The blanking clearance is too small; G. There is no stamping oil or the used stamping oil is highly volatile; H. The blanking clearance is uneven and offset, and the convex and concave dies interfere; I. The precision of the stripping insert is poor or worn, and the precision guidance function is lost; J. The mold guide is inaccurate and worn; K. Improper selection of materials and hardness of male and female dies; I. The guide part (pin) is worn; M. Improper setting of gasket.
(2) Countermeasures: A. Solve the problems such as chip jumping, chip material blocking and clamping; B. Pay attention to feeding, trim the material belt and clean the mold in time; C. Modify the design, increase the overall strength of the punch, reduce the size of the straight edge of the female die, pay attention to the slope or arc of the end face of the punch edge, and cut the small part back; D. The length of the small punch is shorter than that of the large punch by more than one material thickness; E. Modify the design; F. Control the machining accuracy of the male and female dies or modify the design clearance, and properly increase the punching clearance of the small parts; G. Adjust the amount of oil dripping of stamping oil or change the oil type; H. Check the accuracy of each formed part, and adjust or replace it to control the processing accuracy; I. Research or replacement; J. Replace the guide post and guide sleeve, and pay attention to daily maintenance; K. Change the material and use the appropriate hardness; I. Replace the guide part; M. Correct. The number of shims should be as small as possible, and steel pads should be used. The gasket under the concave mold should be placed under the cushion block.
8. Bending deformation size variation
(1) Cause: A. The guide pin is worn and the pin diameter is insufficient; B. The bending guide element has poor accuracy and is worn; C. Bending punch and die wear (pressure loss); D. The mold is not enough; E. The material slips, the bending convex and concave dies have no guide function, and no pre-pressure is applied during bending; F. Poor mold structure and design size; G. The rough edge of the punched part causes poor bending; H. There are many gaskets added to the convex and concave moulds of the bending part, which causes the size instability; I. Variation of material thickness and size; J. Mechanical shape and energy variation of materials.
(1) Countermeasures: A. Replace the guide pin; B. Grind or replace again; C. Grind or replace again; D. Check and correct; E. Modify the design and add guide and preloading functions; F. Modify the design size, break down the bending, add bending shaping, etc; G. Study and repair the cutting edge of the blanking position; H. Adjust and use integral steel pad; I. Replace materials and control the quality of incoming materials; J. Replace materials and control the quality of incoming materials.
9. Height of stamping parts (when there are more than one the first mock examination)
(2) Cause: A. Rough edge of punched parts; B. The stamping parts are crushed and there are scraps in the mold; C. The convex and concave dies (bending position) are pressed or damaged; D. Turnover during punching and shearing; E. Wear and pressure loss of relevant pressing parts; F. The tear size of the relevant tear position is inconsistent, and the blade is worn; G. The pre-cutting depth of relevant vulnerable parts is inconsistent, and the convex and concave dies are worn or broken; H. The convex and concave dies of the relevant convex parts have broken edges or are seriously worn; I. Defects in mold design.
(2) Countermeasures: A. Study and repair the cutting edge of the blanking position; B. Clean the mold and solve the problem of chips floating; C. Re-research or replace new parts; D. Study and repair the punching knife edge, adjust or add strong pressure function; E. Check, implement maintenance or replacement; F. Repair or replace to ensure the consistent tearing and cutting conditions; G. Check the condition of pre-cutting convex and concave dies, and implement maintenance or replacement; H. Check the condition of male and female dies, and implement maintenance or replacement; I. Modify the design, add height adjustment or add reshaping station.
10. Improper maintenance
(1) Cause: A. The mold has no anti-dazzle function, and the assembly direction and dislocation (referring to different positions) are caused by negligence during mold assembly; B. The inserts that have offset the gap are not restored as they are.
(2) Countermeasures: A. Modify the mold and add the function of prevention against fooling; B. Make marks on the mold, and make necessary inspection and confirmation on the care belt after the mold is assembled, and make written records for easy inquiry.
In the stamping production, the daily maintenance of the die is very important, that is, the daily attention should be paid to check whether the press and die are in normal condition, such as the supply of stamping oil and the refueling of the guide part. The inspection before the mold is put on the machine, the inspection of the blade and the confirmation of the locking of each part can avoid many unexpected accidents. When repairing the mold, we must think first and then act, and carefully record and accumulate experience.