Optimization of rubber molding adhesion: reduce the frequency of mold cleaning and stabilize edge quality

# Rubber molding adhesion optimization case: reduce the defective rate in 10 days and increase the mold cleaning cycle to 130-170 molds

# Project overview

• Industry/Scenario: Rubber molded parts (shoe materials and industrial rubber parts)
• Production method: Single shift continuous production
• Core Goal: Reduce mold sticking and edge tearing in the back end, stabilize shift output and reduce mold clearing pauses

# Initial questions

Customers have three types of high-frequency problems in the later stages of continuous production:

1. The local mold sticking increases, and the edge tearing ratio increases during demoulding.
2. The edge quality fluctuates significantly between batches, and the rework pressure increases.
3. The frequency of mold cleaning is too high, which affects the stability of the rhythm and effective production capacity.

# Live baseline (before optimization)

• Defect rate: about 3.2%~4.0%
• Mold cleaning cycle: Clean approximately every 80 to 100 molds
• Stability performance: Fluctuations are obvious in the later stages of continuous production, and are more likely to amplify during the handover stage

Statistical caliber: 10 consecutive daily reports for a single shift production line, based on the customer’s current appearance and edge defect determination standards.

# Diagnostic Process (Days 1-3)

This time, we will first conduct a process baseline inspection, and then compare materials to avoid “preconceived formulas”:

1. Check the consistency of spray coverage (spray distance, angle, overlap rate)
2. Record the corresponding relationship between the mold temperature fluctuation range and the sticking position of the mold
3. Compare the release force and residual changes under different spray dosages
4. Unify the mold cleaning baseline and then evaluate the adjustment plan to reduce the interference of dirty molds

Diagnostic Conclusion

• The main problem is not “a complete mismatch of materials”, but the inconsistency in mold temperature-beat-spray window leading to unstable results
• During high cycle times, parameter tolerance is insufficient, and slight deviations will be magnified into edge defects and mold sticking problems.

# Implementation Plan (Days 4-10)

• Option A (Process Priority): Establish a mold temperature-beat linkage window and fix the spray coverage boundary
• Plan B (Amount Optimization): Optimize the spraying amount within the executable range and control overspray and underspray
• Option C (Organizational Collaboration): Add a shift handover checklist to reduce parameter drift

Establish on-site SOP simultaneously:

• First article per shift confirmation (edge ​​status + coverage consistency)
• Randomly inspect the appearance of key areas and mold sticking risk points every 2 hours
• Abnormal troubleshooting sequence: Spraying → Mold temperature → Mold cleaning → Dosage setting

# 10 days results (trial production stage)

• Defect rate: reduced from about 3.2% to 4.0% to 1.6% to 2.3%
• Mold cleaning cycle: increased from every 80~100 molds to every 130~170 molds
• Continuous Stability: Fluctuations in the later stages are converged, and quality consistency is improved during the handover stage.

# Reusable experience

1. Make process window consistency first, and then fine-tune the dosage to get stable improvements faster.
2. In rubber molding scenarios, priority should be given to managing the “back-end working conditions” instead of just looking at the performance of the front-end samples.
3. Evaluation using the dual indicators of “defect rate + mold cleaning cycle” is closer to the true cost than looking at single mold efficiency alone.

# Applicable boundary description

The results of this case are based on the customer’s current mold status, material system, temperature and humidity conditions, and production line rhythm. Under different part shapes, demoulding methods and quality standards, it is recommended to conduct sample verification first and then scale up to full line application.

# Consulting advice

If you need to evaluate similar working conditions, we can provide material type, mold temperature range, production line rhythm, current defect distribution and frequency of mold cleaning. We can provide a practical initial process window suggestion.