1. Peeling
When solidified resin particles come out of the mold on the surface of the part, this phenomenon is called peeling or shedding.
Corrective measures: Increase the temperature of the inlet mold to make the resin cure faster. Reduce the line speed to make the resin cure earlier. Stop the line for cleaning (30 to 60 seconds). Increase the concentration of low-temperature initiator.
2. Bubbles
When bubbling occurs on the surface of the part.
Corrective measures:
Increase the temperature of the inlet mold to make the resin cure faster.
Reduce the line speed, which has the same effect as the above measures.
Increase the reinforcement level. Bubbling is often caused by voids caused by low glass fiber content.
3. Surface cracks
Surface cracks are caused by excessive shrinkage.
Corrective measures:
Increase the mold temperature to cure speed.
Reduce the line speed, which has the same effect as the above measures.
Increase the loading of fillers or glass content to increase the toughness of the resin-rich surface, thereby reducing shrinkage, excitation, and cracks.
Increase the content of low-temperature initiator or use an initiator below the current temperature.
Add surface pads or veils to the part.
4. Internal cracks
Internal cracks are usually related to excessive section thickness and can occur in the center of the laminate or on the surface.
Corrective measures:
Increase the temperature at the feed end to allow the resin to cure earlier.
Reduce the mold temperature at the end of the mold to act as a heat sink to reduce the peak of the exotherm.
If the mold temperature cannot be changed, increase the line speed to reduce the temperature of the outer contour of the part and the peak of the exotherm to reduce any thermal stress.
Reduce the initiator level, especially high temperature initiators.
Replace high temperature initiators with initiators that have low exotherm but better curing effects.
5. Color difference
Hot spots can cause uneven shrinkage, which can cause color differences (also known as color transfer).
Corrective measures:
Check the heater to ensure that it is in the proper position so that there is no temperature unevenness on the mold.
Check the resin mix to ensure that fillers and/or pigments do not settle or separate (color difference).