Determine the Cause of Cracking in an Epoxy or Urethane Cast Component
Quick Check List:
A- Check if anything has changed in your process. Do not assume!
Common things to look for are:
1) Are you using the proper mix ratio?
2) Are you mixing thoroughly?
3) Material mix temperatures
B- Reasons for epoxy cracking before and during
1) Insufficient mixing of resin and hardener mixture )
2) Uneven edges
3) Incorrect mix ratio
4) Improper cure resulting in excessive shrinkage
5) Vast variation in epoxy wall thickness in the casting
Different heat capacity of internal components resulting in different rates of gelation
Keep in mind if it worked before it is likely that something changed in your process.