Aluminum Motor Housing

The Challenge

A U.S. industrial equipment manufacturer was sourcing aluminum motor housings via sand casting from a domestic foundry. At $42 per unit with 10-week lead times and recurring porosity issues causing a 4% rejection rate, they needed a better process and a more cost-effective supplier — without sacrificing the IP68 sealing requirements critical for outdoor motor applications.

1. Process Engineering & DFM Review

Rather than simply re-quoting the existing sand casting design, our engineering team proposed a process conversion to high-pressure die casting (HPDC). We conducted a full Design for Manufacturability review:

• • Redesigned wall thicknesses from 6mm (sand casting) to 3.5mm (HPDC-optimized) — 40% material savings
• • Added draft angles and revised rib geometry for clean die release
• • Identified 4 critical machined interfaces requiring post-cast CNC finishing
• • Mold flow simulation to eliminate porosity in sealing surfaces

2. Factory Selection & Tooling

We matched the project to a Vietnam die casting facility with:

• • 800-ton cold chamber die casting machines (Toshiba)
• • In-house tool shop with EDM and CNC die machining
• • Integrated CNC machining line for post-cast operations
• • X-ray and CT inspection for internal porosity detection

Tooling was completed in 8 weeks — a 2-cavity die rated for 100,000+ shots. Total tooling investment: $18,500 (amortized at $1.85/unit over the first year).

3. Sample Validation & Pressure Testing

First-article samples were subjected to rigorous testing:

• • Full CMM dimensional report — all 38 features within spec
• • X-ray inspection: zero porosity in sealing zones
• • IP68 pressure test: 1 bar submersion for 30 minutes — pass
• • Surface finish on machined faces: Ra 1.6 μm (spec: Ra 3.2 μm)
• • Powder coat adhesion: cross-hatch test — ASTM 5B rating

4. Production & Logistics

With a 2-cavity die, cycle time is 72 seconds per shot (2 parts). Monthly capacity of 2,500 units easily covers the 800/month demand. Parts are CNC machined, powder coated, inspected, and packed in the same facility — no inter-factory logistics. Finished goods ship FOB Ho Chi Minh City, with ocean freight to the U.S. West Coast averaging 18 days. Total production-to-dock lead time: 4 weeks.