Common Processing Problems
Screw & Barrel Construction Considerations
- Tool steel on screws and barrels ‹ 1-1/2" dia.
- Screws ‹ 1-1/2" dia. use 4140HT steel with hard-faced flights and chrome plated roots
- Barrels ‹ 1-1/2" dia. should have bimetal lining
Screw & Barrel Design Considerations
- Consider downsizing to reduce residency time & increase injection pressure
- Long, gradual transistion areas prevent burning and degradation
- Compression ratio: 2.2:1
- Flight profile: 25% Feed/55% Transistion/20% Metering
- Check ring valve assemblies with free-flow design are recommended