Background and Problem
The client manufactured a wide range of precision machined components — shafts, pins, bushings, brackets, and housings — supplied to 18 different OEM customers with varying call-off schedules. The mismatch between production batch sizes and OEM call-off quantities meant that finished machined parts were held in the finished goods store for periods ranging from 2 weeks to 4 months.
The existing rust preventive — a light-grade RPO applied by spray — was adequate for parts dispatched within 3–4 weeks. For parts held longer, particularly through the monsoon season, rust was developing in storage. Customer delivery inspection was catching rust on 8–12% of batches — triggering return shipments, re-cleaning, and dispatch delays that were damaging customer relationships.
The root cause was twofold: the light-grade RPO had insufficient film strength for extended storage in Indian humidity, and spray application was producing uneven film thickness — thin films in recesses and thread areas that failed before flat surface films.
REFA Solution
REFA recommended upgrading to REFA RPO Medium Grade — a higher film-strength formulation with elevated corrosion inhibitor concentration designed for 3–6 months storage in humid conditions.
Application method was changed from spray to dip-drain with a standardised 4-minute drain time on angled racks. Dip application ensures complete, uniform coverage of all surfaces including internal bores, recesses, and thread roots — the areas most vulnerable to rust. The 4-minute drain time was determined by testing to produce a film weight of 3.2–4.8 g/m² — sufficient for 4–6 months indoor protection.
- Parts inspected for any existing oxidation before RPO treatment — any oxidised parts treated with REFA De-Rusting Solution first
- Dip tank maintained at ambient temperature — no heating required for medium grade RPO
- Drain rack angled at 15° to ensure complete oil run-off and consistent film thickness
- Film weight verification quarterly using standard gravimetric method
Results
Customer delivery rust complaints: zero in the 10 months following process change. Dispatch rejection rate from 8–12% to effectively zero.
- Customer return shipments: eliminated — saving Rs. 2.4 lakhs/month in logistics and re-processing
- Monsoon season storage risk: eliminated — parts held through full monsoon season without rust
- OEM customer satisfaction ratings improved — two customers increased order volumes citing improved delivery quality
- RPO cost increase: Rs. 6 per kg of parts — fully offset by elimination of customer return costs
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