Common problems and solutions in the molding process of SMC and BMC materials

Problem

Causes

Solutions

Adhesive mold

(Materials or products stick to the surface of the mold, causing local roughness of the product)

1. Poor surface smoothness of the mold

2. The material shrinkage rate is too large or too small

3. Excessive pressure

4. The ejection rod of the mold is not parallel

1. Increase the smoothness of the mold

2. Improve the shrinkage performance of materials

3. Properly reduce the molding pressure

4. Check if the ejector rod is balanced

Material shortage and porosity

(Insufficient filling, there are pores on the edges or opposite sides of the injection port of the product)

1. Insufficient pressure

2. Insufficient exhaust

3. The mold temperature is too high or too low

4. Insufficient material quantity

5. Pressing speed too fast or too slow

11. Increase pressure appropriately

2. Increase the number of exhausts

3. Adjust the mold temperature

4. Add materials

5. Adjust the speed of mold closing

Warping and deformation

(Uneven phenomena such as bending and deformation occur after the product is molded)

1. Short holding time and insufficient assimilation

2. The material shrinkage rate is too large

3. The mold temperature is too high

4. Unstructured after mold release

1. Increase pressure holding time

2. Change the material shrinkage rate

3. Adjust the mold temperature appropriately

4. After molding, shape the product until the temperature drops

Carbonization

(Unexhausted gas burns at the edges and corners of the product, causing the area to turn black.)

1. There are dead corners in the mold

2. Insufficient exhaust

3. The mold temperature is too high

1. Improve the exhaust of the mold

2. Increase the number of exhausts

3. Reduce mold temperature

Problem causes and solutions

Adhesive mold (material or product adheres to the surface of the mold, causing local roughness of the product)

1. Insufficient curing and mold temperature discomfort

2. Excessive material shrinkage rate

3. Unbalanced ejection of the ejection rod

4. Improper temperature of the embedded parts

5. The surface of the mold is not smooth and clean

1. Increase curing time and adjust mold temperature

2. Adjust the shrinkage rate of the material

3. Check if the ejector rod of the mold is parallel

4. Proper preheating of inserts

5. Increase the surface smoothness of the mold

Blistering, bubbling

(The surface of the product protrudes after demolding.)

1. The mold temperature is too low and the curing is not sufficient

2. There is moisture in the material

3. The mold temperature is too high

1. Increase mold temperature and increase curing time

2. Check the moisture detection of raw materials

3. Reduce the temperature of the mold

White dots

(There are varying numbers of white spots on the surface of the product)

1. The progress of mold closing is too slow

2. The mold temperature is too high, and the material has been pre cured after being placed

3. Too many deflation times and times

1. Quick mold closing after feeding

2. Reduce mold temperature

3. Quickly exhaust after mold closing and reduce the number of exhausts

Joint

(There are seams at the joint of the product at the corners or opposite the injection port)

1. The mold temperature is too high or too low

2. The closing speed is too fast or too slow

3. Insufficient curing

1. Adjust the mold temperature

2. Accelerate or slow down the closing speed of the mold

3. Increase curing time