Startup Scrap Too High: Molding Process Review

Startup scrap is the rejected material or parts produced while the machine, mold, material, and workflow move from stopped condition to stable production. It should be tracked separately from running scrap because the causes are often different.

Quick Answer

Build a startup checklist before changing normal running settings. Review warm-up, material purge, mold temperature, first insert loading, safety confirmations, operator steps, and the point where parts become acceptable.

What You May See

• Several initial cycles are rejected before stable parts appear.
• Scrap is higher after long stops, material changes, mold changes, or shift changes.
• Startup defects include short shot, burn marks, bubbles, flash, color streaks, or deformation.
• Operators use different startup sequences or judgment standards.
• The process becomes stable later without a clear explanation.

Likely Cause Areas

• Barrel, nozzle, mold, or material may not be thermally stable at the first cycles.
• Previous material or degraded material may remain during startup or changeover.
• Drying, hopper refill, or material handling may not be ready at restart.
• Insert loading, fixture setup, or mold cleaning may vary at the start of production.
• Operators may use different purge, first-shot, inspection, or acceptance steps.
• Maintenance or setup changes may not be recorded before restart.

Safe Checks Before Adjustment

Stop automatic operation if movement, alarm, guarding, or operator safety is uncertain. Do not place hands in the mold, table, injection, or guarded area while movement is possible. Use photos, controller screenshots, cycle logs, and safe observation before changing several settings.

Diagnosis Path

1. Separate startup scrap from running scrap in the production record.
2. Record how many cycles are rejected and what defect appears in each early cycle.
3. Check warm-up time, actual temperature stability, mold temperature, and material drying state.
4. Review purge or material changeover records before the first accepted part.
5. Confirm insert loading and fixture seating steps for the first cycles.
6. Compare different operators or shifts using the same startup checklist.
7. Identify the point where the process becomes stable and what condition changed before that point.
8. Update the startup checklist only after the evidence shows which step controls the scrap.

Evidence to Collect

Check	Why It Matters	Evidence to Collect
Startup defect log	Shows which defect dominates early cycles	Cycle-by-cycle scrap notes and photos
Warm-up condition	Temperature stability often controls first-cycle quality	Temperature screenshots and warm-up time
Material readiness	Drying and purge condition affect startup quality	Drying record, purge notes, material batch
Operator checklist	Consistent startup steps reduce hidden variation	Checklist version and shift notes
Changeover history	Recent work may explain the first unstable cycles	Mold, material, fixture, or maintenance change notes

What Not to Change Too Quickly

• Do not mix startup scrap with normal running scrap in the same diagnosis.
• Do not adjust stable running settings to compensate for a startup-only problem.
• Do not rely on memory for startup steps when shifts or operators change.
• Do not skip safety and warm-up confirmation to reduce startup time.

When to Contact Deboge

Contact Deboge when startup scrap remains high after a controlled checklist is used or when early cycles show alarms, recovery issues, or temperature instability. Send startup logs, defect photos, material records, warm-up screenshots, and machine model.

Related Reading

• Process Issues
• Operation Guides
• Maintenance
• Troubleshooting Center
• Machine Support