TL;DR
Flash is usually excessive pack pressure or clamping force loss from mold wear or incorrect set-point. Verify clamping force and pack pressure before inspecting the mold parting line.
What you might see
- thin film of material at the parting line on parts
- flash visible at side core or insert interfaces
- increased flash after a mold re-installation
- flash worsening as production run progresses
Likely causes
Pack pressure too high for the mold clamping force, opening the parting line
Clamping force set below the process specification or degraded from tie bar wear
Mold parting line worn or damaged, creating a gap that fills with melt
Mold misaligned on the platens from an improper installation
Required tools
- Clamping force verification procedure
- Mold inspection light
- Calipers for flash measurement
- Platen parallelism gauge
Safety first
- Do not remove flash from medical parts with a knife while they are still on the mold. Use the designated degating station.
- Flash fragments are sharp. Use gloves when handling flashed parts.
- Any mold repair must be validated before returning to production per the site change control procedure.
Procedure
- 1
Inspect the flash location on the part. Parting line flash indicates clamping or parting surface issues. Insert or core flash indicates a localized wear issue.
- 2
Verify the clamping force set-point against the validated process record. Check the actual clamping force reading on the machine display.[1]
- 3
If clamping force is below specification, check the mold protection set-point and re-optimize the clamping force through the set-up menu.
- 4
Reduce pack pressure by 5% and inspect parts for flash. Reduce pack pressure only to the point where the part remains dimensionally in spec.
- 5
Inspect the mold parting surface for wear, damage, or foreign material. Clean and inspect under a bright light.[1]
- 6
If the parting surface is worn or damaged, escalate to the toolroom for mold repair. Flash from a damaged parting line will worsen and cannot be corrected by process adjustment.
- 7
Re-check mold alignment on the platens if flash appeared after a recent mold re-installation. Verify platen parallelism.
Sources
Sumitomo SHI Demag Sumitomo IntElect Med Medical Injection Molding Machine general technical documentation, Sumitomo SHI Demag
Sumitomo IntElect Med injection molding machine general flash diagnostics and clamping force procedures (general)
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