how to aviod injection joints

How to Avoid Injection Joints

Product joints are usually caused by low temperature and low pressure at the joints. Below are the key factors and solutions categorized by issue type.

1. Temperature Issues

• Material barrel temperature too low
• Nozzle temperature too low
• Mold temperature too low
• Mold temperature at the joint too low
• Plastic melt temperature uneven

2. Injection Molding Issues

• Injection pressure too low
• Injection speed too slow

3. Mold Issues

• Poor exhaust at the joint
• Poor exhaust of components
• Diversion channel too small
• Gate too small
• Inlet diameter of three channels too small
• Nozzle hole too small
• Gate too far from joint — consider adding an auxiliary gate
• Product wall thickness too thin, causing premature solidification
• Core offset, resulting in one-sided thinning
• Mold offset, causing one side to be thin
• Parts too thin — thicken at seams
• Unequal filling rates
• Interruption of filling material flow

4. Equipment Issues

• Plasticizing capacity too small
• Pressure loss in material barrel too large (plunger type injection press)

5. Material Issues

• Material contamination
• Material flowability too poor — add lubricant to improve flowability