01
Porosity shows up after the finish pass
Gas or shrinkage voids sit just under the skin. The casting looks fine, then the last 0.3 mm opens them up. You scrape the lot, or you weld and re-cut. Both cost more than the casting did.
Machined Casting
Machined Casting
Cast near-net shape, then machine the critical faces to ±0.005 mm. Both steps run in our Dongguan and Singapore plants, so the casting and the finishing cut answer to one set of tolerances.
±0.005 mmRa 0.2–0.8 μm4,000 mm max sizeNo MOQ12-hour DFMISO 9001 / IATF 16949
15 yearsCasting and CNC since 2011
127High-precision CNC machines
±0.005 mmAchievable machined tolerance
99.99%Qualification rate
Where it goes wrong
Four problems that start before the first cut
Most failures in this process are decided at the foundry, not at the spindle.
02
No stock left on the datum face
The pattern wears, the mold shifts, and one face comes in 0.5 mm low. There is nothing to clean up. The whole batch is scrapped because a single reference surface ran out of material.
03
Two suppliers, one tolerance stack
The foundry measures its own way. The machine shop measures another. Neither owns the final dimension, so the argument lands on your desk with a rejected shipment and a line that is waiting.
04
Machining time eats the casting savings
A casting that arrives 2 mm oversize turns into hours of roughing on a 5-axis center. The per-part casting price looked good. The finished part did not.
How we handle it
Cast and machine under one roof, one tolerance callout
Casting gets you the shape. Machining gets you the fit. Splitting them across two vendors is where the money and the schedule go.
Step one
Cast stock that leaves the right amount of material
We quote machining stock as a number, not a habit. Critical faces get 0.5–1.5 mm depending on alloy and part size. Faces that stay as-cast get none. That is decided in DFM, before the tool is cut.
Investment casting suits thin walls and fine detail. Gravity casting suits mid-size aluminum parts where tooling cost matters. Die casting suits the volume runs. Sand casting covers the large iron and steel pieces. The part picks the process, not the other way around.
- 1Draft and fillets checked firstPull direction and corner radii reviewed against the CAM setup before release.
- 2Datum carried throughThe same reference used at the foundry is the one we clamp on.
- 3Stock modeled, not guessedEach machined face has a stated allowance in the quote.
Step two
Machine the interfaces, leave the skin alone
Bores, spigots, sealing faces, bolt patterns, threads. Those are the surfaces that decide whether the part works. Everything else stays as-cast, because cutting a cosmetic surface costs money and buys nothing.
We hold ±0.005 mm where the drawing needs it and Ra 0.8–1.6 μm on most sealing faces. Tighter finishes, down to Ra 0.2–0.8 μm, are available when a seal or a bearing race demands it. Both are measured and reported.
- 116 simultaneous 5-axis centersAngled ports and compound faces in one setup, fewer re-clamps.
- 216 mill-turn centersTurned diameters and cross features without a second operation.
- 34,000 mm max part sizeLarge housings and frames still fit the envelope.
Process selection
Which casting route fits your part
Pick by wall thickness, volume and alloy first. Surface finish and tolerance come second.
| Process | Best for | Typical alloys | Watch out for |
|---|---|---|---|
| Investment casting | Thin walls, fine detail, small to mid parts | Stainless, tool steel, superalloys | Higher per-part cost at low volume |
| Gravity casting | Mid-size aluminum parts, moderate volume | Aluminum, light alloys | Slower cycle than die casting |
| Die casting | High-volume runs, tight as-cast detail | ADC12, zinc, magnesium | Tooling cost needs volume to pay back |
| Sand casting | Large iron and steel components | Iron, carbon steel, aluminum | Coarser as-cast surface, more stock |
What we do
Services around the cast part
One supplier from pattern to packed box.
01
Metal Die Casting
Aluminum, zinc and magnesium parts on high-volume tooling. Near-net detail that keeps machining stock low.
02
Vacuum Casting
Silicone tooling for bridge volumes and design checks. Same geometry language as the production casting.
03
5 Axis CNC Machining
Compound angles, ports and contoured faces on castings that would need three setups otherwise.
04
CNC Milling & Turning
Bores, faces, threads and turned diameters. The fits that make the casting a working part.
05
Part Surface Finishing
Anodizing, plating, powder coating, bead blasting and laser marking on finished castings.
06
Rapid Prototyping
Machined or printed pre-cast prototypes so the fit is proven before tooling is committed.
Capability
Shop envelope and process limits
Numbers we can quote against today.
| Item | Range | Notes |
|---|---|---|
| Machined tolerance | ±0.005 mm (±0.0002 in) | On stated critical faces |
| Fine finish | Ra 0.2–0.8 μm | Sealing and bearing surfaces |
| Standard finish | Ra 0.8–1.6 μm | Most mating faces |
| As-machined finish | Ra 1.6–3.2 μm | Non-critical surfaces |
| Maximum part size | 4,000 mm | Largest travel 4,000 × 400 × 150 mm |
| Rotary table | Ø400 mm | Multi-face work in one setup |
| Order quantity | One piece to 10,000+ | No minimum order quantity |
Why GreatLight
What you get that a split supply chain cannot
15Y
Casting and CNC since 2011
Fifteen years of quoting stock allowances that survive the finish pass. The allowance is a number in the quote, not a hope.
±0.005 mm
Stated tolerance, measured
Critical faces are inspected and reported. If the drawing says ±0.005 mm, that is what the report shows.
12 h
Quote and DFM turnaround
Drawings go in, you get a quotation plus a free DFM analysis within 12 hours. Production can start within 24 hours.
100%
Inspection before shipment
Raw material check, in-process monitoring and final inspection on every order. Reports on request.
3 plants
Dongguan and Singapore
7,600 m² of manufacturing space and 150 technicians across three wholly-owned plants.
0 MOQ
One part or ten thousand
No minimum order quantity. A single prototype casting and a production run go through the same setup discipline.
7,600 m²Manufacturing space
150Technicians on staff
<2%Historical late-delivery rate
3–5 daysTypical ship time for parts
Industry fit
What these sectors require, and what we deliver
Aerospace brackets and housings
Thin-wall castings where weight matters and every bore is a fit.
- ±0.005 mm
- Ra 0.8–1.6 μm
- Full inspection report
Automotive and EV housings
Sealing faces and bolt patterns on cast enclosures that see vibration.
- IATF 16949:2016
- Sealing face control
- 10,000+ part runs
Pump and valve bodies
Flow passages left as-cast, mating flanges machined flat and true.
- Ø400 mm rotary table
- Leak-face flatness
- One setup per face group
Robot and automation frames
Large cast structures with machined mounting pads and dowel holes.
- 4,000 mm max size
- Pad height control
- No MOQ
FAQs
Questions engineers ask before releasing a cast part
When is a machined casting cheaper than cutting from solid?
When the part has internal cavities, curved passages or a lot of removed volume. Cutting those from billet wastes material and spindle time.
Stay with solid stock when the part is small, prismatic, and has few internal features. At that size the casting setup and tooling cost do not pay back.
How much machining stock should I leave on a casting?
It depends on the process and the alloy. Investment castings usually need 0.5–1.0 mm on machined faces. Sand castings need more, often 2–3 mm, because the as-cast surface is coarser.
We state the allowance per face in the DFM report. If a face cannot spare that material, it should be redesigned or the process changed.
Which casting process gives the best surface finish?
Investment casting gives the smoothest as-cast surface, which often means less machining. Die casting is close behind on aluminum and zinc.
Sand casting leaves the roughest skin. It is still the right choice for large iron and steel parts where finish is not the driver.
Can you machine a casting supplied by another foundry?
Yes. Send the casting drawing plus the finished part drawing. We check the stock allowance against our setup before quoting.
If the supplied casting has no stock on a critical face, we will tell you before we cut. That is cheaper than discovering it after.
What shapes are hard to cast and then machine?
Very thin walls next to tight bores. The wall can deflect under clamping before the bore is cut. Deep narrow pockets with high length-to-diameter ratios are also difficult to reach with a cutter.
Sharp internal corners fight both processes. A fillet at the corner helps the casting fill and lets a larger cutter reach the floor.
How do you control porosity so it does not appear after machining?
Process control at the pour, plus enough stock on critical faces to cut past the skin. Vacuum-assisted routes reduce gas entrapment on aluminum parts.
For pressure-tight parts we inspect after machining, not before. A void that never reaches the surface is not a defect. One that does, is.
What lead time should I plan for?
Quotation and free DFM analysis come back within 12 hours. Production can start within 24 hours of approval, and parts typically ship in 3–5 days.
Tooling for a new casting pattern adds time on top of that. The DFM report states it before you commit.
Do you sign an NDA before I share drawings?
Yes. Uploads are secure and treated as confidential, and an NDA is available on request before any file changes hands.
We do not reuse a customer's casting geometry, tooling design or drawing for any other project.
Send the casting drawing and the finished part drawing
You get a quotation, a stock-allowance check and a free DFM analysis within 12 hours. No minimum order quantity, and every part is inspected before it ships.
12-hour quote and DFM100% inspectionNo MOQNDA on request
