1. Master Pattern
A precise master is produced by SLA, PolyJet, or CNC machining, then finished to define the final molded surface.
Polyurethane Casting Services
Production-like plastic and rubber parts for prototypes, bridge production, and low-volume manufacturing.
10-200 pcs
Low-volume runs
±0.010 in
Typical tolerance
Shore A-D
Rigid to flexible
What is Polyurethane Casting?
A soft-tooling process for production-like plastic parts without hard tooling.
Polyurethane casting, also called urethane casting, vacuum casting, RTV molding, or silicone molding, uses a master pattern and silicone mold to cast polyurethane resin into detailed plastic or rubber-like parts.
It is ideal when 3D printing does not provide the required surface quality or material feel, but injection molding tooling is too expensive or too slow for the current product stage. Fengnuo supports appearance samples, functional prototypes, market-test batches, bridge production, and low-volume end-use parts.
Casting Process
From master pattern to finished low-volume parts.
Each project is reviewed for part geometry, visible surfaces, split lines, mold life, material choice, color, and inspection requirements before production begins.
2. Silicone Mold
Liquid silicone is poured around the master and cured, creating a flexible mold that captures fine detail and texture.
3. Material Selection
Polyurethane resin is selected to match rigidity, flexibility, transparency, impact strength, heat resistance, or color needs.
4. Vacuum Casting
Resin is cast into the silicone mold under vacuum or controlled conditions to reduce bubbles and improve detail replication.
5. Curing & Demolding
Parts cure, are removed from the mold, and are trimmed to remove gates, vents, and flash.
6. Finishing & Inspection
Painting, polishing, inserts, graphics, and dimensional checks are completed according to the approved specification.
Casting Capabilities
Production-like appearance with flexible low-volume manufacturing.
Rigid Plastic-Like Parts
ABS-like, PC-like, PP-like, and acrylic-like parts for housings, covers, brackets, and presentation samples.
Flexible Rubber-Like Parts
Shore A elastomer options for grips, seals, pads, buttons, protective covers, and soft-touch features.
Clear & Translucent Parts
Clear urethane and tinted parts for lenses, light pipes, transparent covers, display models, and visual checks.
Color Matching
Pigmented casting and painting support for brand colors, product samples, and market-ready appearance models.
Inserts & Hardware
Threaded inserts, molded-in hardware, post-machined holes, and assembly support for functional test parts.
Overmolded Effects
Two-material appearance and soft-touch prototypes with mechanical bonding features designed into the part.
Polyurethane Materials
Material families that mimic common thermoplastics and elastomers.
Final resin selection depends on stiffness, impact strength, flexibility, transparency, heat exposure, flame rating, color, and surface finish.
ABS-Like
General-purpose rigid material for enclosures, covers, appearance models, and functional prototypes.
PC-Like
Rigid and tough options for structural prototypes, housings, and higher-impact applications.
PP-Like
Slightly flexible parts where a polypropylene-like feel, hinge behavior, or chemical resistance is desired.
PMMA / Acrylic-Like Clear
Clear or translucent visual parts, light covers, lenses, windows, and display samples.
Rubber-Like Shore A
Flexible elastomeric parts for seals, gaskets, grips, bumpers, buttons, and protective soft components.
High-Temp / FR Grades
Specialty polyurethane materials for heat exposure, flame-retardant needs, and demanding validation work.
Surface Finishes
Finishing options for visual samples and functional assemblies.
As Cast
Fast, practical finish after trimming and cleaning for engineering prototypes and internal testing.
Matte / Frosted
Soft non-reflective appearance for electronics, handheld products, and early visual samples.
Semi-Gloss / High-Gloss
Polished presentation surfaces for showroom models, consumer product samples, and clear parts.
Painting
Color matching, cosmetic refinishing, texture control, and improved show-model appearance.
Texture Replication
Molded or finished texture for grip, fingerprint reduction, and injection-molded appearance.
Clear Polishing
Improves transparency for lenses, light guides, windows, covers, and display components.
Graphics & Marking
Silk-screening, pad printing, labels, markings, and decorative product details.
Inserts & Assembly
Threaded inserts, drilling, tapping, bonding, and simple assembly for test-ready parts.
Sizes & Tolerances
Practical expectations for silicone tooling and cast urethane parts.
Casting accuracy depends on the master pattern, resin, part geometry, wall thickness, mold age, split line, and post-processing. Critical dimensions should be marked on 2D drawings.
| Item | Practical Guideline |
|---|---|
| Typical tolerance | ±0.010 in or ±0.003 in/in, whichever is greater; tighter features reviewed case by case |
| Metric reference | Typical local targets around ±0.10-0.25 mm depending on geometry and material |
| Shrinkage | Plan for resin and flexible mold behavior; 0.15%-0.30% is a common review range |
| Wall thickness | 1.0 mm+ recommended; 0.5 mm may be possible for small local features after review |
| Draft | Not always required, but 3-5 degrees improves demolding and mold life |
| Mold life | Usually 15-25 castings per silicone mold; complex geometry or special resin may reduce yield |
Design Guidelines
Design for repeatable casting, clean surfaces, and stable assembly.
Good casting design reduces mold wear, air traps, warpage, color risk, and finishing rework.
Keep walls practical
Uniform wall thickness helps reduce deformation, sink, and stress during curing.
Add radii and fillets
Inside radii improve strength, material flow, and production quality.
Define visible surfaces
Mark A-surfaces so split lines, gates, texture, polish, and paint can be planned early.
Use ribs carefully
Ribs should support stiffness without creating thick intersections or demolding problems.
Plan inserts and bosses
Use proper boss wall thickness, base radii, and mechanical support for screws and hardware.
Design for color and finish
Pantone targets, gloss level, clear polishing, and paint thickness should be reviewed before production.
Advantages of Polyurethane Casting
- Lower tooling cost and shorter lead time than injection molding.
- Production-like color, texture, surface quality, and material feel.
- Flexible material range from clear rigid plastic to soft rubber-like parts.
Things to Consider
- Silicone molds wear over time, so repeat batches may require new molds.
- Very tight tolerances, flatness, and exact color matching need early review.
- For high-volume production, injection molding may become more economical.
Applications
Low-volume cast parts for product validation and market launch.
Consumer Electronics
Enclosures, buttons, bezels, display models, connector housings, and soft-touch features.
Medical Devices
Device housings, ergonomic handles, covers, prototypes, and presentation samples.
Automotive
Interior trim, light covers, ducts, handles, brackets, pre-production parts, and test samples.
Robotics
Grippers, covers, sensor housings, protective pads, brackets, and validation assemblies.
Industrial Equipment
Control housings, covers, handles, guards, soft pads, transparent windows, and short-run parts.
Product Development
Looks-like models, functional test parts, sales samples, pilot builds, and investor demo parts.
Polyurethane Casting FAQ
Answers before you send CAD files.
What is polyurethane casting?
It is a low-volume molding process that uses a master pattern and silicone mold to cast polyurethane resin into rigid, flexible, clear, or colored plastic parts.
When should I choose it over 3D printing?
Choose polyurethane casting when you need better surface quality, production-like material feel, color, texture, rubber-like parts, or multiple copies that should look consistent.
How many parts can one silicone mold make?
A typical mold may produce about 15-25 parts. Geometry, undercuts, resin type, texture, and required quality can increase or reduce this number.
What tolerances can polyurethane casting achieve?
A common expectation is ±0.010 in or ±0.003 in/in, whichever is greater. Critical dimensions should be marked on drawings for review.
Can you make clear or colored parts?
Yes. Clear, translucent, pigmented, painted, matte, gloss, and textured finishes can be reviewed based on geometry and material choice.
What files are needed for a quote?
STEP, IGES, X_T, STL, OBJ, and PDF drawings are useful. Please include quantity, color target, material requirements, visible surfaces, finish, and application details.
Get a Polyurethane Casting Quote
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