Case study on optimization of mold adhesion and surface pores of precast concrete components: stable demoulding within two weeks and reduced frequency of mold cleaning

# Precast concrete demoulding case: reduce porosity and mold sticking in two weeks, and increase the mold cleaning cycle to 120-150 molds

# Project overview

• Industry/Scenario: Concrete precast components (standard parts of wall panels and beams and columns)
• Production method: Single shift continuous production
• Core Goal: Stable demoulding and reduce the frequency of appearance rework and mold cleaning without changing the main equipment.

# Initial questions

During the high temperature period in summer, three typical problems occur on site:

1. After demoulding, the mold is partially stuck and the corner damage rate increases.
2. The pores and hair blooms on the surface of components increase, and the pressure for appearance rework increases.
3. Mold contamination is accelerating, and the frequency of mold cleaning is relatively high, affecting effective production capacity.

# Live baseline (before optimization)

• Defective appearance rate: about 3.6%~4.2%
• Mold cleaning cycle: Clean approximately every 70 to 90 molds
• Demolding stability: Fluctuations are obvious in the later stages of continuous production (more prominent in night shifts)

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

# Diagnostic Process (Days 1-3)

This time, we did not change the formula first, but completed the process baseline inspection first:

1. Check the uniformity of spraying (spray distance, angle, overlap rate)
2. Record the relationship between mold temperature fluctuation range and defect distribution
3. Compare the changes in residue and release force under different dilution ratios
4. Make formula comparisons after unifying the mold cleaning baseline to avoid “misjudgment of dirty molds”

Diagnostic Conclusion

• The main contradiction is not that the release agent is ineffective, but that the spray consistency and dilution ratio fluctuate, resulting in unstable results.
• The original process window during the high temperature period is too narrow and the parameter tolerance is insufficient.

# Implementation Plan (Days 4-10)

• Option A (Process Priority): Fixed spray window, limiting dilution fluctuation range
• Option B (Formulation Synergy): Switch to a water-based release system that is more suitable for the current mold temperature range
• Plan C (beat optimization): Standardize the “waiting time from spraying to mold closing” to reduce the “half-dry and half-wet” state

Establish on-site SOP simultaneously:

• First piece confirmation per shift
• Random inspection of spray coverage and appearance defects every 2 hours
• Abnormal priority troubleshooting order: Spraying → Mold temperature → Mold cleaning → Formula

# Two-week results (trial production stage)

• Defective appearance rate: reduced from about 3.6% to 4.2% to 1.4% to 2.0%
• Mold cleaning cycle: increased from every 70~90 molds to every 120~150 molds
• Demolding stability: Night shift fluctuations are significantly reduced, and the consistency of continuous production is improved.

# Reusable experience

1. Doing “process consistency” first, and then discussing “formula pros and cons” can significantly reduce misjudgments.
2. In the case of precast concrete, the selection of release agent should be defined simultaneously with the mold temperature range.
3. Evaluation using the dual indicators of “defect rate + mold cleaning cycle” is closer to the true cost than just looking at the unit price.

# Applicable boundary description

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

# Consulting advice

If you need to evaluate similar working conditions, the following parameters can be provided: component type, mold temperature range, production line rhythm, demoulding method and current defect manifestation. We can provide a practical initial process window suggestion.