Aluminum Die Casting Gear Housing: Material, Design & OEM Guide

An aluminum die casting gear housing — also called a reducer housing or gearbox housing — is a precision cast enclosure that supports the gears, bearings and shafts of a speed reducer or gearbox, while keeping lubricant sealed inside and contaminants out. Aluminum alloy die casting is the preferred process for producing these housings at volume because it combines light weight, good thermal conductivity, tight dimensional repeatability and low unit cost.

This guide covers how to choose the material, design the part and order a custom, leak-tight housing.

Why choose aluminum die casting for gear housings

• Light weight with high stiffness: a strong strength-to-weight ratio cuts gearbox weight versus cast iron.
• Heat dissipation: good thermal conductivity helps a running gearbox shed heat and protect the lubricant and bearings.
• Dimensional repeatability: die casting holds tight, consistent tolerances part to part, so bearing bores and mating faces stay in spec across large runs.
• Low cost at volume: once the mold (tooling) is built, per-part cost is low, ideal for series production.
• Near-net shape: thin walls, ribs, bosses and mounting features are cast in one shot, minimizing machining.

Recommended material: ADC12 vs A380

Most gear and reducer housings are cast in ADC12 (equivalent to A383 / EN AC-46100). It offers the best all-round balance of castability, strength and pressure tightness. A380 is a common alternative for higher-load structural parts.

• ADC12: excellent castability and pressure tightness; the default choice for oil-holding gearbox housings.
• A380: very good castability and higher strength; suited to structural or higher-load housings.

For most gearbox housings that must hold oil, ADC12 is the default choice thanks to its excellent pressure tightness.

Key design considerations

• Wall thickness: typically 2.5 to 4 mm; keep walls uniform to avoid shrink porosity.
• Draft angle: around 1 to 3 degrees on walls for clean ejection.
• Ribs and bosses: add ribs for stiffness; core out bosses to reduce mass.
• Bearing bores and sealing faces: cast close to size, then CNC-machine to final tolerance.
• Machining allowance: leave 0.5 to 1 mm stock on critical machined surfaces.
• Sealing: flat, machined mating faces plus a gasket or O-ring groove for oil tightness.

Good design keeps walls uniform, avoids thick sections that trap shrinkage, and reserves precision features — bearing seats, sealing faces, threaded holes — for CNC finishing.

Leak-tightness: critical for gear housings

A gearbox housing must hold oil without weeping. Micro-porosity in the casting can cause slow leaks, controlled two ways:

• Casting quality: proper gating and process control on cold-chamber machines to minimize porosity.
• Vacuum impregnation: sealing residual micro-porosity so the housing passes pressure and leak tests.

We run an in-house impregnation line specifically to deliver leak-tight housings, followed by leak testing where required.

Surface treatment options

• As-cast and deburred
• Shot blasting for a uniform matte finish
• Powder coating for corrosion protection and appearance
• Machined and passivated sealing faces

Quality and inspection

Critical dimensions — bearing bore diameter and concentricity, sealing-face flatness, bolt-hole positions — are verified on a CMM (coordinate measuring machine). Production is managed under an ISO 9001 quality system, with first-article inspection and in-process checks.

How to order a custom or OEM gear housing

We are a China-based aluminum die casting manufacturer producing gear and reducer housings on a make-to-drawing / OEM basis:

• Send your 2D/3D drawing or a sample part.
• We review DFM — wall thickness, draft, machining, sealing — and quote.
• We build the in-house die-casting mold and run samples on 180 to 500 ton cold-chamber machines.
• CNC machining, impregnation, surface finishing and CMM inspection.
• First-article approval, then series production and export.

FAQ

Which aluminum alloy is best for a gearbox housing

ADC12 is the usual choice for its excellent castability and pressure tightness; A380 suits higher-load structural housings.

Can a die-cast aluminum housing be oil-tight

Yes. With controlled casting plus vacuum impregnation and leak testing, housings reliably hold lubricant.

Do you make the tooling in-house

Yes. We design and build the die-casting mold in-house, then machine and inspect the parts under one roof.

What sizes can you produce

Housings are cast on 180 to 500 ton cold-chamber machines, covering a wide range of small to medium reducer and gearbox housings.

Need a quote? Send your drawing for a custom aluminum die casting gear housing — ADC12, leak-tight, machined and inspected.