Plastic Injection Molding Problems and Their Solutions

 

Plastic injection molding presents an array of pros. A few of them include quick production speed and flexibility in shape and size. Another is automation in operation, which lowers its overall cost. Moreover, it accurately produces its products and allows us to make complex parts. This eco-friendly method is ideal for the field of molding. This involves dealing with complex shapes and mass production. However, there are a few certain plastic injection molding problems. They often involve mold design and materials. Luckily are our experts at Creatingway are adept at dealing with them.

The Plastic Injection Molding Problems and Their Solutions

• Short shots

Short shots arise when we are unable to fill the mold cavity completely. A few of its causes are as follows. Firstly, the die temperature, injection speed, or pressure may be too low. Also, the raw material may have low liquidity. In addition, the part may be too thin or its gate size is very small. It may also arise when we cure the polymer melt prematurely. This occurs when the structural design is not reasonable.

We have come up with the following solutions to this plastic injection molding problem. In terms of the material, we first prefer using material that is more fluid. In the case of mold design, we first fill the thick walls then proceed to fill the thin walls. This helps us avoid the retention problem. We also opt to increase the size and number of the gates. This aids in lowering the process ratio and flow resistance. Another solution is placing the exhaust port properly. This curbs the problem of poor exhaustion

• Brittleness

Brittleness arises when a plastic easily cracks or breaks at some point. It may occur during dry conditions or the use of over recycled materials. The plastic injection molding temp may also be wrong. Moreover, the melting set mark may not be high. Luckily, we have come up with a few solutions to this problem. In terms of the material, we first set the proper drying conditions. We then lower the use of recycled matter and focus on raising a portion of raw materials. Finally, we use high-strength plastic that is less likely to be brittle.

In terms of the machine, we prefer choosing a well-designed screw. This improves the temperature supply when forming the plastic. In the case of the process, our experts opt to first lower the nozzle and cylinder’s temperature. They then lower the screw speed, back pressure, and injection speed. This contributes toward lowering brittleness.

• Trapping of Air

Air traps create bubbles in the part undergoing plastic injection molding. It may arise when air is unable to escape from the ram, parting surface, or vent. This ideally occurs when two melt front meet. We have come up with the following solution to this problem. In terms of mold design, we first add a vent to the last-filled place. Also, we can redesign the runner and gate system. In the case of structural design, we can lower the varying wall thickness. This is by trying to ensure uniform wall thickness. In terms of the process, we first lower the injection speed and the final stage. We can then proceed to raise the mold temperature.

• Burn Marks

Burn marks arise when we fail to remove the gas in the cavity in time. This causes the blackening of the end flow. It may also arise when the materials degrade. This occurs due to overcast screw speed, over high melt temp, or an improper runner system. Luckily, we have a few solutions that help us avoid burn marks during plastic injection molding.

In terms of the mold design, we first add an exhaust system. We specifically install it where the gas easily arises. We can then increase the runner system’s size. In terms of the process, we first lower the injection speed and pressure. We can then lower the temp or confirm if the thermocouple or heater is working properly.

• Delamination

It involves the part’s surface peeling off layer by layer. This plastic injection molding problem may arise when we mix incompatible polymers. It may also occur if we use an excess amount of release agent. In addition, an uneven resin temp and excess moisture may contribute towards it. Luckily, we have a few solutions that aid us in avoiding delamination.

In terms of the materials, we first avoid mixing incompatible or contaminated materials. A quality check is vital. In terms of the mold design, we chamfer all gates or runners with sharp angles. When it comes to the process, we raise the mold and barrel temperature. Moreover, we can dry the material properly, prior to molding. It also helps when we avoid using an excess release agent. In case of any inquiries or quotations regarding plastic injection molding, simply contact us.

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