Background and Problem
Forged crankshaft blanks arrive at the machining unit with heavy forging lubricant — a graphite-based compound applied during the hot forging process. This material is extremely tenacious: it is designed to remain on the metal surface under extreme forging pressures and temperatures, and it does not release easily to standard cleaning chemistry.
The client’s single-stage spray degreaser was not removing the graphite forging lubricant completely from the crankshaft forging surface. Residual graphite was contaminating the phosphating bath gradually, reducing bath efficacy, and producing patchy phosphate coating. The OEM was returning parts with paint adhesion failures that were traced back to incomplete phosphating, which was traced back to incomplete cleaning.
The problem had been attributed to the phosphating chemistry for months before REFA’s audit identified the actual root cause at the cleaning stage. The phosphating bath was being corrected repeatedly without addressing the contamination source — a fundamental diagnostic error that cost the client months of poor quality output.
REFA Solution
REFA recommended a two-stage cleaning process replacing the single-stage spray system:
Stage 1: REFA Heavy-Duty Alkaline Degreaser — Pre-Soak Tank
Parts are immersed in REFA Heavy-Duty Alkaline Degreaser at 7% concentration, 70°C, for 4 minutes. The elevated temperature and concentration are required to emulsify and lift the graphite forging lubricant. The product’s high-solvency surfactant system penetrates between the graphite particles and the metal surface, breaking the adhesion formed during forging.
Stage 2: REFA Standard Alkaline Spray Degreaser — Final Cleaning
After pre-soak, parts go through the standard spray degreaser stage at 3.5%, 58°C — removing residual contamination and degreaser residue. Followed by hot water rinse and rust preventive rinse before phosphating.
Results
Phosphate coating failures: eliminated. Paint adhesion rejection at OEM: zero in the 5 months following process change.
- Phosphating bath life extended from 3 weeks to 9 weeks — no more graphite contamination loading
- Paint shop first-pass yield improved from 82% to 99.1%
- OEM quality rating: improved from ‘Conditional’ to ‘Preferred Supplier’ grade
- Pre-soak tank installation cost recovered through phosphating bath chemical savings within 4 months
- Annual saving on phosphating bath replacements and paint rework: estimated Rs. 11.4 lakhs
Looking for heavy-duty alkaline degreasers for forged component cleaning and pre-phosphating treatment?
Contact REFA Chemical Industry – Greater Noida | Our founder brings 25+ years of industrial chemical expertise to every solution we supply. Call or WhatsApp for free samples and technical consultation.