We cast 25 to 50 copies from one silicone mold, using a CNC-machined or 3D printed master. Same two weeks, same batch, no steel tooling. Quote and DFM notes back within 12 hours.
If any of these sound familiar, the tooling route is probably the wrong route.
Injection tooling only pays back above a few thousand parts. Below that, the steel cost sits on your books and the amortized piece price never looks right. A silicone mold spreads a few hundred dollars across a small batch instead.
A single machined prototype hides process variance. Ten parts from one silicone mold show whether your fit, snap fits and assembly sequence survive a real batch. Finding that at 30 units is cheaper than finding it at 3,000.
Machined surfaces read as machined. Buyers and test users notice tool marks, stepped radii and visible layer lines. Cast urethane comes out of a silicone cavity with a matte or textured skin, so the parts in the room look like the parts you intend to ship.
Every week before design freeze, a steel tool is money at risk. If the rib thickness or the boss location changes, the tool is scrap. Soft tooling absorbs two or three revisions inside the same pilot phase, and the master is re-machined, not re-cut.
A short run of copies pulled from one soft mold, with the master underneath controlling every dimension.
The master is the part you already approved. We machine it from aluminium or ABS on our 5-axis centers to ±0.005 mm, or print it when the geometry is organic. Surface finish on the master transfers to every copy, so it gets sanded and sealed before anything else happens.
The master is suspended in a casting box and degassed silicone is poured around it. We cure the block, then cut it open along the parting line and pull the master out. What is left is a cavity that matches the master to a few hundredths of a millimeter.
Two-part polyurethane is mixed, degassed and poured into the closed mold inside a vacuum chamber. Pulling the air out before the resin gels is what keeps bubbles out of thick sections and sharp corners. Without the vacuum step, a 15 mm boss fill is where you find voids.
Cured parts come out in 24 to 48 hours depending on the resin, and we de-flash, sand, prime and paint them as a batch. Because every copy comes from the same cavity, part 1 and part 40 measure the same. Shrinkage runs about 0.15 to 0.25 percent, less than injection-molded plastics, so the master is scaled up before machining.
The right process depends on quantity, tolerance and how settled the design is.
| Route | Best fit | Where it loses |
|---|---|---|
| Vacuum casting | 25–50 units, cosmetic covers, pilot builds | Soft mold wears out past 30 pulls |
| CNC machining | 1–10 units, tight tolerance, metal parts | Piece cost stays high above 20 units |
| Injection molding | 3,000+ units, frozen design | Tool cost and lead time before first part |
| 3D printing | 1–5 units, fit checks, complex geometry | Layer lines, limited resin properties |
Casting rarely travels alone. These are the services we keep in-house so the master, the copies and the finish stay on one schedule.
Silicone molds and cast urethane parts, 25 to 50 per mold, in rigid and rubber-like resins.
CNC and printed masters for the casting cell, plus functional prototypes in production-like materials.
16 simultaneous 5-axis centers cutting masters and inserts to ±0.005 mm.
SLA, SLS and FDM masters when the geometry is organic or the wall thickness is under 1 mm.
Anodizing, plating, powder coating, bead blasting, polishing and laser marking.
Brackets, housings and chassis so the cast cover arrives with something to bolt onto.
Numbers below come from our own equipment list and inspection records.
| Item | Range | Note |
|---|---|---|
| Master tolerance | ±0.005 mm | Machined on 5-axis centers |
| Shrinkage | 0.15–0.25% | Master scaled up before cutting |
| Parts per mold | 25–50 | Thin features wear sooner |
| Mold life | 20–30 pulls | Silicone, cut open and re-clamped |
| Cure time | 24–48 hours | Depends on resin and section |
| Max part size | 4,000 mm | Limited by casting box and chamber |
| Surface finish | Ra 1.6–3.2 μm | As cast, before paint or texture |
| Inspection | 100% | Dimensional report on request |
The same shop cuts the master and pours the mold. No handoff between a machinist and a caster, so the shrinkage factor gets applied once, by the person who measured the part.
16 simultaneous 5-axis centers hold ±0.005 mm on the master. That number is the floor for every copy that comes out of the cavity.
Send STEP, STL or X_T files and get a price plus manufacturability notes inside 12 hours. Production can start within 24 hours of approval.
Standard cast and finished batches leave in 3 to 5 days. Historical late-delivery probability sits under 2 percent.
One prototype or a 10,000-part run, same intake. The route changes, the paperwork does not.
ISO 9001, IATF 16949, ISO 13485 and ISO 27001. Uploads stay confidential and an NDA is available on request.
Cable-routed housings and joint covers cast in semi-rigid urethane, then painted to match the production color.
Pilot-build bezels and clips cast from a CNC master, checked against the mating part before the batch is released.
Smooth, cleanable surfaces on small enclosures, molded over metal inserts so the threads are metal, not resin.
Thin-wall covers with molded standoffs, cast in a flame-rated resin and laser marked after finishing.
Plan for 25 to 50 pulls. The limit is not the resin; it is the silicone tearing at sharp corners, thin ribs and deep bosses.
If your part has 1 mm walls or a 40 mm deep pocket, expect the lower end and budget a second mold for a 50-piece run.
Dimensional tolerance tracks the master, which we machine to ±0.005 mm. Cast copies typically land within ±0.1 mm on stable features.
Long thin parts warp more than they shrink. If a 300 mm cover needs to stay flat, we add a fixture or cast it in a more rigid resin.
Rigid, semi-rigid, rubber-like and transparent polyurethanes, plus grades with higher heat deflection for under-hood or electronics use.
Tell us the service temperature and whether the part needs to flex. Resin selection matters more than mold design for drop performance.
Send STEP, STL, X_T, IGES or native SolidWorks and we handle the rest. Draft of 1° to 2° on vertical faces helps release from the silicone.
Avoid undercuts that lock the part in the cavity. If they are functional, we cut the mold in more than two pieces.
Yes. We prime and paint to a supplied color reference, and texture can be molded in from the master or added as a sprayed finish.
Send the reference with the order. Color matching on cast urethane is done by eye against your sample, not by a spectrophotometer reading.
Below a few hundred units, casting wins because there is no steel tool. Above a few thousand, injection molding wins because the piece price drops hard.
The crossover sits around 200 to 500 parts for most enclosure-sized geometry. We will tell you when the numbers flip.
3D CAD, quantity, resin preference if you have one, surface finish, and any color or texture reference.
A drawing with critical dimensions speeds up the DFM notes. Without one, we quote on the model alone.
Uploads are secure and confidential, and we sign an NDA on request before files change hands.
ISO 27001 covers how we store and move customer data inside the company.
Upload your CAD and we return a price plus DFM notes within 12 hours. No minimum order quantity, from one part to a full pilot batch.
12-hour quote100% inspectionNo minimum order quantityNDA on request
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Upload your 3D model or 2D drawing and get a quotation with a free DFM analysis. Maximum processing size 4,000 mm.
CNC Metals 13 grades
CNC Plastics 10 grades
Machines & processes 12 options
Surface & post-processing 10 options
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