Urethane Casting Services — Custom Plastic Parts in 7–10 Days

Get production-quality urethane cast parts for prototypes, bridge production, and low-volume runs. Clarwe uses silicone tooling and vacuum casting to deliver rigid, flexible, rubber-like, and clear plastic parts with smooth molded surfaces — no hard tooling required. Quantities from 10 to 200 parts, with lead times from 7 to 10 business days. 

• Production-like surface finish and cosmetic quality on every part

• ABS-like, PC-like, rubber-like, and optically clear material options

• Custom colors, painted finishes, and threaded inserts supported

• ISO 9001:2015, AS9100D, and ISO 13485:2016 certified facility

What You Get With Clarwe Urethane Casting

Clarwe's urethane casting service is built for engineering teams that need functional, production-representative parts before committing to hard injection mold tooling. Using platinum silicone molds and vacuum casting under controlled conditions, we produce parts that closely replicate the surface quality, dimensional accuracy, and material feel of injection-molded components — at a fraction of the tooling cost and lead time.

Whether you need a single appearance model, a set of functional prototypes for testing, or a short bridge production run while permanent tooling is being built, urethane casting gives you parts that are ready to use, not just ready to look at.

Every order includes dimensional inspection before dispatch. Our certified quality management system covers the full process from master pattern review through final part release.

Urethane Casting Capabilities and Tolerances

Part Size and Quantity Range

Urethane casting is most cost-effective for quantities between 10 and 50 parts per run. For larger quantities up to 200, mold replacement is factored into the quote. Contact us if your requirement falls outside these ranges.

Dimensional Tolerance and Accuracy

Tolerance accuracy depends on the quality of the master pattern, part geometry, wall uniformity, and material type. Parts with deep undercuts, thin walls below 1 mm, or heavily asymmetric geometry may require tolerance review at quoting. Provide your critical dimensions and GD&T callouts with your CAD file for a precise assessment.

Lead Time and Turnaround

Rush orders for simpler geometries can be completed in 5 business days. Lead time increases for parts requiring painting, color matching, insert installation, or secondary machining. All lead times begin from the date of confirmed order and approved master pattern.

Materials for Urethane Casting

Urethane casting materials are selected to match the mechanical and visual properties of your intended production polymer. Clarwe stocks a range of two-part polyurethane resins covering rigid, semi-rigid, flexible, and elastomeric applications, as well as optically clear formulations.

Rigid Urethane Materials (ABS-like, PC-like, PP-like)

All rigid formulations are available in natural (off-white/cream), black, or custom color-matched finishes.

Flexible and Rubber-Like Materials

Flexible materials are well-suited for parts that need to flex, compress, or seal against another surface. Shore hardness targets can be specified at order. Note that shrinkage rates are slightly higher for softer formulations — we account for this at the mold-making stage.

Clear and Optically Transparent Urethanes

Clear urethane formulations are cast under full vacuum to minimize bubble formation and achieve maximum optical clarity. Suitable for display covers, lenses, light pipes, and transparent enclosures.

• Water-clear polyurethane — high clarity, light tint possible

• Tinted clear — color-accurate transparent parts for display or light-diffusion applications

• Note: clear parts require polished master patterns for best surface clarity

Surface Finishes and Post-Processing

Standard Molded Finish

All urethane cast parts are released with a smooth molded surface as standard. Surface quality reflects the finish of the silicone mold, which in turn reflects the master pattern. A satin-to-gloss appearance is typical on cosmetically critical faces. Internal surfaces and features with restricted mold access may show fine parting lines or slight texture variation.

Painted, Textured, and Custom Color Options

Color-matched parts require a color standard or code at time of order. First-article color approval is included for painted orders.

Inserts and Secondary Operations

• Threaded inserts:Heat-set or cast-in brass and stainless steel inserts for mechanical fastening

• Overmolding:Two-material parts combining rigid and flexible urethanes

• Secondary machining:Tight-tolerance bores, threaded holes, or flat reference surfaces added by CNC after casting

• Assembly:Sub-assemblies combining cast parts with machined or sheet metal components available on request

How Urethane Casting Works — Step-by-Step Process

Master Pattern (3D Printed or CNC Machined)

The process begins with a master pattern — a dimensionally accurate representation of the final part. Clarwe produces master patterns using SLA 3D printing for complex geometries or CNC machining for tight-tolerance features. The master is finished to the surface quality required by the end part: sanded, primed, and polished for cosmetic parts; left at machined finish for functional prototypes. Master quality directly determines mold quality and, therefore, part quality.

Silicone Mold Making

The finished master is placed in a mold box and liquid platinum silicone is poured around it. The silicone is degassed under vacuum before pouring to eliminate air inclusions. After curing at controlled temperature, the mold is split, the master is removed, and the cavity is ready for casting. A single silicone mold typically supports 20 to 25 cast pulls before dimensional drift requires mold replacement.

Vacuum Casting and Curing

The two-part urethane resin is mixed with pigment (if required) and degassed under vacuum. It is then poured into the silicone mold under vacuum to prevent bubble entrapment in the part. For opaque parts, the mold is placed in a pressure vessel during cure to suppress any residual porosity. Clear parts are cast under full vacuum throughout. After the specified cure cycle, the mold is opened and the part is extracted.

Finishing and Quality Inspection

Parts are trimmed of any flash, inspected dimensionally against the drawing or CAD model, and finished to the specified surface standard. Critical dimensions are measured using calibrated instruments under our ISO 9001:2015 quality system. Parts are packed individually to protect cosmetic surfaces during transit.

Applications of Urethane Casting

Functional Prototypes and Product Validation

Urethane casting is the preferred process when you need a small number of parts that behave like the final production component — not just look like it. Because the cast materials closely simulate production polymers in stiffness, impact resistance, and surface feel, prototypes can be used for fit checks, assembly trials, load testing, and user evaluation studies. This is especially valuable in the final stages of design validation, where decisions are high-stakes and iteration speed matters.

Bridge Production Before Injection Molding

When injection mold tooling is on order but customer demand or launch timelines cannot wait, urethane casting provides a cost-effective bridge. Silicone tooling can be ready in days rather than weeks, and the cast parts are functional enough for initial customer shipments, packaging development, and supply chain qualification. Once hard tooling is ready, bridge production stops — but the time saved at launch is a genuine commercial advantage.

Market Testing and Show Models

For product launches, trade shows, investor demos, or marketing photography, urethane casting delivers parts with cosmetic quality that is indistinguishable from injection-molded production parts to the naked eye. Custom colors, painted finishes, and clear options mean that the visual story of your product can be told accurately before tooling is committed.

Low-Volume Custom Plastic Parts

Not every product needs injection molding. For specialist equipment, medical devices, aerospace interiors, and custom industrial components with ongoing volumes below 200 parts per year, urethane casting is a permanent production solution — not just a prototype bridge. Silicone molds can be remade as needed, and material and finish changes can be introduced between runs without tooling cost.

Urethane Casting vs Injection Molding — When to Choose Each

Choose urethane casting when your quantities are below 200, your design may still change, or your timeline does not allow for hard tooling. Choose injection molding when you have a locked design and volumes that justify the tooling investment.

Quality Standards and Inspection

Clarwe operates under a certified quality management system covering the full urethane casting workflow — from master pattern acceptance through finished part release. Our certifications applicable to urethane casting work include:

• ISO 9001:2015— General quality management for manufacturing operations

• AS9100D— Quality management for aerospace-grade manufacturing requirements

• ISO 13485:2016— Quality management for medical device component manufacturing

Inspection steps applied to every urethane casting order:

1. Master pattern review— dimensional verification against customer CAD before mold fabrication begins

2. First article inspection— first cast part measured against all drawing dimensions before batch production proceeds

3. Visual inspection— surface quality, color, parting line condition, and finish checked on every part

4. Dimensional sampling— critical dimensions checked at frequency defined by order quantity

5. Packaging inspection— individual part protection verified before packing for dispatch

Inspection records are retained and available on request. For AS9100D and ISO 13485 orders, full first article inspection reports (FAIR) and material certifications can be provided.

Why Choose Clarwe for Urethane Casting

Fast silicone tooling. Production-quality results. No over-engineering.

Clarwe exists for engineering teams that need accurate, functional parts quickly — without managing multiple vendors, chasing lead time updates, or accepting prototype-grade quality. Our urethane casting service is run from a certified facility in Hyderabad, India, with direct sales contact in the USA (+1 914 530 0349) and UK/Europe (+44 20 381 30481).

• Certified quality system— ISO 9001:2015, AS9100D, and ISO 13485:2016 cover every order

• Fast turnaround— standard lead time of 7 to 10 business days from confirmed order

• Material flexibility— rigid, flexible, rubber-like, and clear urethanes with custom color matching

• Finish options— painted, textured, color-matched, and EMI-shielded finishes available

• Secondary operations— threaded inserts, overmolding, CNC finishing, and assembly on request

• Direct communication— your order is managed by our engineering team, not a marketplace algorithm

• Scalable service— the same process and quality system handles a single prototype and a 200-part bridge production run

Frequently Asked Questions About Urethane Casting

What quantities work best for urethane casting?

Urethane casting is optimised for orders between 10 and 200 parts. For quantities below 10, the per-part cost is higher due to mold amortisation, but single parts and small samples are accepted. For quantities above 200, injection molding typically becomes more cost-effective once tooling cost is factored in. Contact us if you are unsure which process is right for your volume.

What tolerances can Clarwe hold for urethane cast parts? 

Our standard tolerance is ±0.2 mm for dimensions up to 100 mm, with ±0.3 mm per additional 100 mm of part length. Shrinkage of approximately +0.15% is compensated at the master pattern stage. Tighter tolerances on specific features can be achieved by adding CNC machining as a secondary operation after casting. Provide your critical dimension callouts with your CAD file so we can confirm feasibility at quoting.

How fast can I get urethane cast parts? 

Standard lead time is 7 to 10 business days from confirmed order. This covers master pattern review, silicone mold making, casting, curing, finishing, and inspection. Rush orders for simple parts with no secondary finishing can be completed in 5 business days. Complex finishing, color matching, or insert installation adds 1 to 2 business days.

Can you match custom colors or produce clear parts?

Yes to both. For opaque custom colors, pigment is added directly to the resin before casting, giving consistent through-color. For precise color matching, we work from RAL codes, Pantone references, or a customer-supplied physical sample. Clear parts are cast from optically transparent urethane resin under full vacuum to minimise bubbles. Tinted clear options — for light diffusion or colored display covers — are also available.

How does urethane casting compare to injection molding? 

Urethane casting uses low-cost silicone tooling, which makes it fast and affordable for quantities up to around 200 parts. Injection molding requires hard steel or aluminium tooling, which takes weeks to produce and costs significantly more — but delivers lower per-part cost at high volumes. If your design is still evolving, your quantities are under 200, or your timeline is tight, urethane casting is almost always the better choice. See the comparison table above for a full factor-by-factor breakdown.

What file formats do you accept for quoting?

We accept STEP (.stp, .step), IGES (.igs), STL, SolidWorks (.sldprt), Parasolid (.x_t), and PDF drawings for reference. STEP is the preferred format for accurate quoting. Include a PDF drawing with critical dimensions, tolerances, and surface finish callouts if you have specific requirements. Upload your files via our online quote tool or send them directly to sales@clarwe.com.