Background and Problem
Aluminium die casting uses die release agents — sprayed onto the die face before each shot to prevent casting adhesion. These compounds are typically silicone or wax-based and are specifically designed to be chemically inert and strongly adherent to both the die and the casting surface. They do not release easily to standard cleaning chemistry.
The client was experiencing 11–14% powder coating rejection — blistering, peel-off, and fisheye defects concentrated at the parting line and ejector pin mark areas. These are precisely the areas with the highest die release agent concentration on the casting surface.
The cleaning line was a standard 3-stage spray washer using a general-purpose alkaline degreaser at 3% concentration. This product was effective on mineral oil and coolant but had insufficient solvency for silicone and wax-based die release agents. The die release was not being removed — only emulsified enough to appear clean visually while retaining enough film to cause coating adhesion failure.
REFA Solution
REFA recommended switching to REFA Aluminium-Safe Heavy Duty Degreaser — a formulation with enhanced solvency for wax and silicone-type compounds, while remaining safe for aluminium surfaces (pH 9.5–10.5, maximum 60°C).
- Concentration increased from 3% to 5.5%
- Temperature optimised at 58°C — higher temperature increases wax and silicone solubility
- Contact time extended from 90 seconds to 150 seconds — critical for die release removal
- Spray pressure standardised at 2.0 bar — ensures die release is mechanically displaced as well as chemically emulsified
- Rinse stage upgraded to two-stage cascade — ensures all emulsified die release is fully rinsed before phosphating
Results
Powder coating rejection rate reduced from 12.5% to under 1.2% within 4 weeks of process change.
- Monthly coating rework cost reduced from Rs. 3.6 lakhs to under Rs. 35,000
- OEM supplier quality rating improved from ‘Conditional Approval’ to ‘Full Approval’
- Die release agent contamination in phosphating bath: significantly reduced — bath life extended from 4 to 11 weeks
- Annual saving on coating rework and phosphating bath: estimated Rs. 9.2 lakhs
Looking for aluminium-safe heavy duty degreasers for die cast component cleaning and coating pre-treatment?
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