To help ensure continued molding success, this blog focuses on three different types of flashing problems, their possible causes, and corrective actions you can take for each.
|Possible cause||Corrective action|
|1. Poor mold spot||Spot mold to ensure fit and vent depths at ~0.025mm (0.001in).|
|2. Injection Pressure too high||Reduce pressure. This may require higher melt temperature or lower injection speed.|
|3. Coost time too long||Shorten boost time, lower boost pressure, or move transfer to an earlier position.|
|4. Insufficient clamp tonnage||Increase clamp pressure or move to a machine with more tonnage.|
Flash and Short Shot in Different Shots:
|Check ring inconsistent; worn barrel||Check and replace assembly ring. Replace/reline barrel as needed.|
Flash and Short Shot in Same Shot:
|Possible Cause||Corrective action|
|1. Core shift||Check wall thickness for core shift. Investigate for source of core shift and repair mold.|
|2. Inadequate clamp tonnage||Increase clamp pressure or move to a machine with more tonnage.|
|3. Fill speed or pressure too high||Reduce speed or fill pressure.|
|4. Melt temperature too low||Check and raise melt temperature if needed.|
|5. Sprue too long too small, "O" dimension||Install correct-size sprue.|
TMI TIP: Tritan can be successfully ultrasonic welded using energy director and shear-joint designs. The resulting device can exhibit outstanding impact strength, clarity, and durability—without weld joint flashing.
For more information about flashing, talk with your Eastman technical service representative. You can also download an Injection Molding Troubleshooting Guide (specify medical or durables).
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|TMI TIP: Metal coatings infused with PTFE usually can be chemically stripped with minimal damage to the substrate. However, be aware of special process tips for aluminum molds or when certain coatings penetrate the substrate. Order your free poster to see these tips and more.|
Expect a balance of important advantages with Eastman Tritan™ copolyester MX711.
- Chemical resistance
- Hydrolytic stability
- Compatibility with sterilization methods
- Secondary operations and assembly
- Heat resistance
Eastman Tritan™ copolyester MX711 is well-suited for medical-device applications that demand superior chemical resistance, clarity and hydrolytic stability, including:
- IV system components
- Blood therapy devices
•Select a compatible gating style for the selected resin. Most conventional cold gating styles work well with copolyesters. For hot runner systems, valve gates should be used.
Design Tooling with good Cooling/Thermal Control
•Copolyesters require good thermal control throughout the cavity for optimal processing.
Design Tooling with a plan for venting
•Poor venting can result in burn marks and incomplete fill.
Design Tooling with a plan for ejection
•Parts should be adequately supported during ejection to avoid part deformation/breakage
Click here for more successful processing tips