What are the common production failures of blow molding machines?

1、 The blow molding machine does not discharge
1. The starting temperature is low, which may be caused by the damage of the extrusion barrel and parts. Check whether the temperature of the extrusion barrel and die head and other parts meet the standard, whether the heating time is sufficient, and whether the heater is damaged, and replace it in time.
2. If there is glue sticking at the feeding part, first lower the temperature before stopping, and then stop the machine when there is no glue at the screw feeding part. When the machine is just started, it is necessary to use plastic rod or wooden rod to squeeze down at the feed inlet; Material, so that the colloid sticking to the feed part of the screw moves forward.
3. The problem of the drive belt may be that the drive belt is old or too loose, resulting in unstable discharge. Replace and adjust the belt tension to avoid any further loose and falling off affecting the feeding.
Plastic hollow molding equipment
2、 Black substances exist on the surface of blow molded products
There are many reasons for black minerals or short black lines in the transparent part of blow-molded products.
1. The retention time of raw materials in the blow-molding barrel or the flow channel is too long, and the material properties change.
2. The blow molding screw and barrel are severely worn, and the raw materials cannot be uniformly melted.
3. Poor cooling water of the mold causes large deviation of the overall temperature of the mold.
4. The mold exhaust is poor, and the air accumulates in the mold cavity, causing scorching.
3、 Surface bubbles
During the process of blow molding, the surface of the product was formed and the gas that could not be discharged in time was trapped, resulting in defects on the surface of the blow molding product.
1. The blow molding material is wet, and the water vapor evaporates into the material surface.
2. The mold exhaust is blocked or the exhaust is poor, and the gas cannot be discharged smoothly.
3. The blow molding cycle time is too short, and the cavity gas cannot be discharged quickly.
4. The machine production air pressure parameter setting error.
5. The blow molding screw rotates too fast.
6. The screw back pressure is too low.
7. There are volatile additives in the raw materials.
Multi-layer blow molding machine equipment
4、 Low surface finish
1. The blow molding pressure is not enough, and the raw materials are not completely compacted.
2. The barrel temperature is too low, and the raw materials are not completely melted, resulting in low finish of the products.
3. The temperature exhaust of the mold is insufficient, and the product cannot be close to the inner surface of the mold, which causes problems in the production process.
4. The raw material is wet, and the fluidity is not good when it enters the production process of the blow molding machine, which will also cause the reduction of the surface finish.
5、 Uneven longitudinal wall thickness of products
1. The dead weight droop of the mould is serious. This problem can be improved by reducing the melt temperature of the mould, increasing the extrusion speed of the mould, replacing the resin with low melt flow speed, and adjusting the control device of the mould.
2. The difference between the diameters of the two longitudinal cross sections of blow-molded products is too large, which affects the production. To solve this situation, we can appropriately change the product design and adopt the bottom blowing method for molding.
Blow-molded products production equipment
6、 Blow-molded products are transversely uneven
1. The parison extrusion is skewed. Due to the failure caused by this reason, the gap width deviation of the die shall be adjusted in time to make the parison wall thickness uniform; Straighten the mold before closing.
2. The temperature difference between the inside and outside of the mold sleeve and the mold core of the blow molding machine is large, so it is necessary to increase or reduce the heating temperature of the mold sleeve and improve the temperature deviation between the inside and outside of the die.
3. The shape of the product is asymmetrical. Before the mold is closed, pre-clamping and pre-expansion of the parison can be carried out to make the parison shift to the thin-wall direction properly, which can improve this problem.
4. If the blow expansion ratio of parison is too large, it can be solved by adjusting and reducing the blow expansion ratio of blow molded products.
7、 The outline or graphics of blow molded products are not clear
1. If the cavity exhaust is poor, repair the mold in time, sandblast the cavity or add an exhaust slot.
2. Low inflation pressure, increase the inflation pressure of the blow molding machine.
3. The melt temperature of the parison is low, and the material is not plasticized properly. Increase the heating temperature of the extruder and the head properly, and add an appropriate amount of filler masterbatch if necessary.
4. If the cooling temperature of the mold is low and the mold has condensation, just raise the mold temperature above the dew point temperature.