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Silicone & Urethane Casting

Silicone and urethane casting is an excellent way quickly manufacture high-quality plastic cast parts in small to medium quantities (~10-1000 parts) with shorter lead times and lower tooling costs than injection molding. In fact, it has some of the lowest unit costs of any manufacturing technology, including 3D printing, while rivaling injection molding for quality and versatility.

Cast plastic parts are durable and inexpensive. They consistently render fine surface details and offer high-quality finishes with the look and feel of consumer products. Because they are significantly less expensive than injection molding, silicone and urethane casting are also useful for quickly creating prototypes for molded parts.

A High-Quality Alternative to 3D Printing and Injection Molding

Urethane and silicone casting are a versatile middle ground between 3D printing and injection molding that can offer the best of both worlds. Modern advances in materials have made silicone and urethane cast parts comparable in quality to injection molded parts. At the same time, these cast parts can be produced in small to medium quantities faster and at less cost than with injection molding.

When compared to 3D printing, silicone and urethane casting materials have a wider range of chemical, thermal and mechanical properties than 3D printed plastics.. Because they are not restricted by the size of a printing bed, cast parts also offer better value for medium to large parts. Lastly, cast parts have superior finish and fine detail when compared to 3D printed parts, which means they can accurately create the look and feel of consumer products without any additional finishing.

Common applications for rapid casting include:

high precision aluminium part manufacturing by casting and machining
  • Electronic housings

  • Gaskets

  • Panels

  • Food-safe products

  • Medical devices

  • Performance parts for transportation and aerospace

  • Outdoor products

  • Fixtures

  • Cosmetic parts

  • Displays

3D Printed Master Patterns

Whenever applicable, we use 3D printing to create the master patterns for silicone and urethane mold-making, so you can have tooling in weeks, not months. Because urethane casting is so good at rendering fine details, it can easily reproduce custom finishes, saving time and money. If you have a part that you need replicated, we can easily reverse engineer existing objects with 3D scanning as well.

Once created, each mold can be used to cast thousands of parts with the look, feel and durability of finished products. Because they are relatively quick and inexpensive to produce, silicone and urethane molds are also a cost-effective option for iterating prototypes for cast or molded parts.

large silicone rubber crab mold and master pattern

Versatile Cast Urethane and Silicone

Urethane and silicone molds can cast a range of materials, including elastomers and rigid plastics, as well as silicone, plaster and even concrete. Cast plastic parts can range from 20A – 90D on a durometer and come in high-heat, flame-retardant, food-safe and medical-grade options.

As a result, cast parts can stand up to a variety of specialty applications in demanding environments including the aerospace, medical and food industries. We can even work with other materials like concrete and plaster! Contact us if you don’t see the material you want to use below.

Casting Medical Device

Rigid Materials

Low Cost/General Purpose

Hard Pro 70-3

Lowest cost, fast-curing rigid urethane. Popular choice for general uses. Not suited to high-stress applications.

Durometer: 70D

Hard Pro 70-3 data sheet



ABS-like material. Extremely tough and rigid, not suited to applications that require flexibility.

Durometer: 80D

TP-4050 data sheet



Polypropylene-like material. Very flexible and tough. Not suited to high-stress applications which require rigidity.

Durometer: 78D

TC-879 data sheet

Clear Acrylic-Like

Innoclear 7086

Clear, acrylic-like resin with high UV stability. Expensive and slow to cure. May require multiple molds.

Durometer: 80D

Innoclear 7086 data sheet

Food and Medical Grade

Steralloy R-Series

Food-grade and biocompatible urethane for medical applications. Relatively expensive compared to other materials.

Durometer: 76D-85D

Steralloy R-Series data sheet

High Heat


High-heat resin with 345°F heat operating temperature. Extremely rigid, not suited to flexible applications.

Durometer: 80D

TP-4020 data sheet

UL 94 V-1 Flame Retardant

Inno-FR 4016

UL 94 V-1 flame-retardant polyurethane with ABS-like mechanical properties. More expensive and slower to cure than TP-4050.

Durometer: 70D

Inno-FR 4016 data sheet

UL 94 V-0 and FAR 25.853 Flame Retardant

Inno-FR 4014

UL 94 V-0 and FAR 25.853 flame-retardant polyurethane. Better flame rating than Inno 4016 but not as stiff or durable.

Durometer: 70D

Inno-FR 4014 data sheet

Tooling Composite


Heavy aluminum-filled composite for tooling. Zero shrink, dissipates heat and extremely rigid. Not for mechanical parts.

Durometer: 88D

TASK 18 data sheet


General-Purpose Rubber

BJB F-Series

Fast-curing, flexible urethane rubber material with a range of applications. Available in all A hardness ratings.

Durometer: 5A-95A

BJB F Series data sheet

General-Purpose Silicone

MoldStar 20T

Fast-curing platinum silicone, able to cheaply make many parts a day. Cures too fast for larger parts.

Durometer: 20A

MoldStar 20T data sheet

Tooling Silicone


Durable, slow-curing platinum silicone for tooling and large volumes. More expensive than urethane and Moldstar 20T.

Durometer: 42A

P44 data sheet

Food-Grade Rigid Silicone

Smooth Sil 960

Green, food-grade silicone approved for direct food contact. Relatively high rigidity and low shrinkage.

Durometer: 60A

Smooth Sil 960 data sheet

Food-Grade Soft Silicone

SORTA-Clear 37

Clear, food-grade silicone approved for direct food contact. Less rigid than Smooth Sil. Low shrinkage.

Durometer: 37A

SORTA-Clear 37 data sheet

Start Casting Today

If you’re ready to start a cast urethane or silicone project, get a free quote in 24 hours or less by filling out our quick quote form.

Interested in our other services? RapidMade is your go-to source when it comes to 3D Printing for Prototyping and more.

Our engineers will review your project and get back to you with a cost estimate and project analysis. Want to learn more? Give us a call!