01
Thin walls that never fill
Aluminum die casting below 1.5 mm on a long flow path gives you cold shuts and short shots. Stainless investment casting can hold 2 mm, but the pour temperature is higher and the shell cost climbs fast.
Casting Material Selection
Stainless Steel Aluminum Casting: Which Fits
Both alloys pour, but they fail differently. We cast and machine both in house, so we can tell you which route your part should take before tooling is cut.
ADC12 die casting316L investment casting±0.005 mm post-machining12-hour DFM reviewNo minimum order quantity
15 yearsCasting and machining since 2011
127High-precision CNC machines
7,600 m²Across 3 wholly-owned plants
99.99%Qualification rate
Failure modes
Where casting projects go wrong
Most casting problems are decided before the first shot. Here is what we see on incoming drawings.
02
Porosity found after machining
Gas porosity stays hidden until the face is cut. A leak test on a casting that looked fine can scrap a whole lot. Pressure-tight parts need vacuum assist or a different process.
03
Corrosion in the wrong alloy
Aluminum needs anodizing or a coating to survive salt and washdown. Choosing the cheaper alloy to save cost per part often costs more once the finish line is added.
04
Tooling paid before the design settles
A die cut around a drawing that still moves is money gone. Casting rewards frozen geometry. If the housing might change next month, prototype first.
How we choose
Pick the process from the part, not the price list
Five questions decide most casting calls.
Alloy behavior
What each alloy does well
Aluminum wins on weight and thermal conductivity. A die-cast ADC12 housing at 2.5 mm wall weighs roughly a third of the same part in stainless, and it pulls heat away from electronics far better. Machining is fast and tool wear is low.
Stainless wins on strength and corrosion without a coating. A 316L investment casting holds up in marine air, food lines, and medical washdown. It also takes a weld and a polished finish that aluminum cannot match.
- 1WeightAluminum density is about one third of stainless.
- 2Corrosion316L resists chlorides bare; aluminum needs a finish.
- 3FinishStainless polishes and passivates; aluminum anodizes.
Process limits
Where each process stops making sense
Die casting needs volume to pay back the die. Below a few thousand parts a year, the tooling sits in the cost of every unit. Aluminum is also the harder one to weld after casting, so a design that joins two castings later should be reviewed early.
Stainless casting works at higher temperature and holds finer detail, but the shell and pour cost more per kilogram. For small brackets and one-off housings, cutting from bar or plate on a 5-axis mill is faster and cleaner than building a pattern.
- 1VolumeDie casting pays back in the thousands, not the dozens.
- 2GeometryUndercuts and thin ribs favor machining or investment.
- 3Lead timeNo tooling means parts in 3–5 days.
Side by side
Casting comparison at a glance
Typical values for production work, not lab samples.
| Factor | Aluminum (ADC12) | Stainless (316L) |
|---|---|---|
| Minimum wall | 1.5–2.0 mm | 2.0–3.0 mm |
| Density | About 2.7 g/cm³ | About 8.0 g/cm³ |
| Corrosion, bare | Needs anodize or coating | Good without coating |
| Thermal conductivity | High | Low |
| Machining speed | Fast, low tool wear | Slower, higher tool wear |
| Typical process | Die casting, vacuum casting | Investment casting |
| Best volume | Thousands and up | Tens to thousands |
What we run
Casting and machining under one roof
Tooling, pour, and finish do not leave the building.
01
Metal Die Casting
Aluminum ADC12 housings and covers with vacuum assist where pressure tightness matters.
02
Vacuum Casting
Small-batch aluminum and urethane parts for design validation before a die is cut.
03
5 Axis CNC Machining
16 simultaneous 5-axis centers cut cast faces, bores, and sealing grooves in one setup.
04
CNC Milling & Turning
Mill-turn centers handle stainless bodies and inserts without a second fixture.
05
Rapid Prototyping
Check fit and flow before committing to tooling. From one piece upward.
06
Part Surface Finishing
Anodizing, passivation, plating, and bead blasting to the drawing.
Scope
Shop range and what is included
Numbers you can plan a program around.
| Item | Range | Notes |
|---|---|---|
| Maximum part size | 4,000 mm | Larger travel on request |
| Tolerance | ±0.005 mm | After machining, not as-cast |
| Surface finish | Ra 0.2–3.2 μm | Depends on operation |
| Stainless grades | 303, 304, 316L, 17-4PH | Plus 420, 430, 440C |
| Aluminum grades | 6061, 7075, ADC12 | Plus 2024, 5052, 6082 |
| Order size | 1 to 10,000+ | No minimum order quantity |
| Inspection | 100% before shipment | Reports on request |
Why GreatLight
Why engineers send both alloys here
15Y
Casting and cutting since 2011
Pattern, die, pour, and finish stay in our own plants. Fewer handoffs, fewer excuses.
±0.005 mm
As-cast is not the final word
Critical faces are machined after casting, so the tolerance on the drawing is the tolerance you measure.
127
Machines ready after the pour
16 simultaneous 5-axis centers plus 16 mill-turn centers take cast parts straight to finished geometry.
12 h
Quote and DFM in half a day
Wall thickness, draft, and parting line get checked before you commit to tooling.
4
Certifications held
ISO 9001:2015, IATF 16949:2016, ISO 13485:2016, ISO 27001:2022.
99.99%
Qualification rate
Raw material check, in-process monitoring, and final inspection on every order.
3Wholly-owned plants
150Technicians
24 hProduction start
<2%Historical late-delivery rate
Industry fit
What each industry asks of the alloy
Automotive and EV
Weight and heat path drive the call. Aluminum housings, machined faces, IATF 16949 process control.
- ADC12 die casting
- ±0.005 mm faces
- IATF 16949
Electronics enclosures
Conductivity and finish matter more than strength. Anodized aluminum, sealed faces, clearance for boards.
- Ra 0.8–1.6 μm
- Anodizing
- 100% inspection
Medical and food hardware
Washdown and corrosion rule out bare aluminum. 316L investment castings, passivated and deburred.
- 316L
- ISO 13485
- Passivation
Industrial machinery
Brackets and manifolds in low volume favor machining over a die. No tooling to amortize.
- 1 to 10,000+ parts
- 3–5 day ship
- No MOQ
FAQs
Questions we get before tooling
Is stainless steel or aluminum casting cheaper?
It depends on volume and finish. Aluminum die casting has a higher tooling cost but a lower cost per part once you are into thousands. Stainless investment casting has a lower entry cost and stays practical at tens to hundreds of parts.
Add the finishing line before you compare. Anodizing aluminum is not free, and skipping it in the quote is how projects go over budget.
Which alloy holds thinner walls?
Aluminum die casting can reach 1.5 mm on short flow paths with good fill. Long paths and thin ribs short-shot, so we usually ask for 2 mm there.
Stainless investment casting holds about 2 mm reliably. Below that, we would rather machine the feature than cast it.
Can you machine castings to tight tolerance?
Yes. As-cast surfaces carry draft and parting-line steps, so we machine sealing faces, bores, and mounting pads after the pour.
Machined features hold ±0.005 mm and finishes from Ra 0.2–3.2 μm depending on the operation.
How do you handle porosity?
For pressure-tight aluminum parts we use vacuum assist and keep the gate and overflow layout generous. Stainless investment castings get a controlled shell and pour temperature.
If a part must be leak-tight, tell us at quote. That changes the process choice, not just the inspection plan.
When is CNC machining better than casting?
When the design is still moving, when the annual volume is low, or when the geometry has undercuts, deep pockets, or thin ribs that a die cannot fill.
Cutting from bar or plate skips tooling entirely. Parts ship in 3–5 days, and a revision costs a program change, not a new die.
Do you cast and machine in the same plant?
Yes. Casting, CNC machining, and finishing are in house across three plants in Dongguan and Singapore. That keeps the tolerance chain short when a casting becomes a finished part.
What is the minimum order quantity?
There is no minimum order quantity. We run from one prototype to 10,000+ part runs, so you can validate a design before committing to production tooling.
How fast can I get a quote?
Quotation and a free DFM analysis come back within 12 hours. Production can start within 24 hours after the drawing and material are locked.
Uploads stay confidential, and an NDA is available on request.
Send the drawing, get the process call
We will tell you whether the part should be cast in aluminum, cast in stainless, or cut from solid, and quote it either way.
12-hour quoteFree DFM analysis100% inspectionNo minimum order quantity
