Vacuum Casting Materials Guide

Material options, properties, and typical applications

When you select a vacuum casting supplier, material choice is just as important as dimensional accuracy. The right polyurethane (PU) or silicone resin can simulate injection-molded plastics, rubber parts, and even transparent lenses at a fraction of the tooling cost and lead time.

This guide gives product engineers a clear overview of the most common vacuum casting materials, their grades, key advantages, and typical applications.

1. ABS-like Polyurethane Resins

1.1 Introduce

ABS-like resins are rigid polyurethane systems formulated to mimic the mechanical behavior and surface finish of injection-molded ABS. They are a good “default choice” for functional prototypes and general-purpose housings.

1.2 Typical Grades / Hardness

Shore D 75–82

Heat deflection temperature (HDT) typically 60–80 °C

Available in natural (off-white), black, and custom colors

(Examples often marketed as “ABS-like,” “PC/ABS-like,” or “High-Impact” PU in material catalogs.)

1.3 Key Advantages

Good balance of stiffness and impact resistance

Easy to paint, texture, and glue

Suitable for tapping, inserts, and light mechanical assembly

Good dimensional stability for most geometries

1.4 Typical Applications / Parts

Consumer electronics enclosures and covers

Handheld device housings and frames

Automotive interior trim prototypes

Appliance and instrument panels

General purpose proof-of-concept and fit-check parts

2. PC-like / High-Impact Polyurethane Resins

2.1 Introduce

PC-like resins are tough, rigid systems designed to simulate polycarbonate or PC/ABS blends, with higher impact resistance and better heat performance than standard ABS-like materials.

2.2 Typical Grades / Hardness

Shore D 80–86

HDT typically 80–110 °C, depending on grade and post-cure

Available in natural or transparent tints; can be tinted smoke, grey, etc.

2.3 Key Advantages

High impact strength and good notched performance

Better heat resistance for functional tests near elevated temperatures

Good for snap-fits and clips (with proper design)

Stable under repeated opening/closing cycles

2.4 Typical Applications / Parts

Structural brackets and functional frames

Snap-fit panels, clips, and latches

Automotive interior / under-hood prototypes (non-safety critical)

Tool handles, housings for power tools and industrial devices

Pilot run parts where mechanical behavior is critical

3. PP-like / PE-like Flexible Resins

3.1 General Description

PP-like and PE-like polyurethane systems simulate semi-flexible thermoplastics such as polypropylene. They are slightly flexible, offer good fatigue resistance, and are suitable for living hinges, thin walls, and parts that require flexing without cracking.

3.2 Typical Grades / Hardness

Shore D 60–75 or Shore A 80–95 (semi-flexible)

Relatively low density and good flexural fatigue resistance

3.3 Key Advantages

Good toughness and flexibility

Suitable for living hinges and snap-fits with larger deflection

Reduced risk of brittle fracture under repeated bending

Good chemical resistance to many everyday fluids (depends on grade)

3.4 Typical Applications / Parts

Hinged covers and flaps

Cable grommets, strain reliefs

Flexible clips and hooks

Reservoir caps and lids

Low-stress protective shells and guards

4. Transparent / PMMA-like Resins

4.1 Introduce

Clear polyurethane systems simulate PMMA (acrylic) or clear PC. They are used whenever optical appearance, light transmission, or internal visibility is important.

4.2 Typical Grades / Hardness

Shore D 80–85 (rigid)

Light transmittance up to 85–90% for high-clarity grades

Can be water-clear or tinted (smoke, grey, amber, etc.)

4.3 Key Advantages

High transparency and good polishability

Ideal for light pipes, windows, and aesthetic lenses

Can be dyed or tinted for functional or cosmetic purposes

Supports post-polishing and clear coating to enhance appearance

4.4 Typical Applications / Parts

Light guides, light pipes, and lenses (non-safety critical)

Indicator windows and display covers

Automotive lamp housings prototypes

Transparent reservoirs, covers, and sight glasses

Concept models for lighting and optical design

5. Rubber-like Elastomeric Resins (TPU-like)

5.1 Introduce

Rubber-like materials are polyurethane elastomers that simulate TPE, TPU, or silicone rubber. They cover a wide range of hardness and are widely used for over-mold simulations and soft-touch parts.

5.2 Typical Grades / Hardness

Shore A 30–90 (soft to firm)

Some grades are food-contact or skin-contact capable (depending on supplier)

5.3 Key Advantages

High elasticity and rebound

Good tear resistance and flex-fatigue behavior

Suitable for over-mold feel (used together with rigid substrates)

Can be colored in a wide range of Pantone-matched colors

5.4 Typical Applications / Parts

Seals, gaskets, and O-ring-like profiles

Shock absorbers, pads, and vibration dampers

Over-mold grips for tools and electronic devices

Wheels, rollers, and flexible connectors

Wearable straps and cushioning components

6. High-Temperature & Engineering-Grade Materials

6.1 Introduce

For applications that need to withstand elevated temperatures or more demanding mechanical loads, special high-temperature and engineering-grade polyurethane systems are available.

6.2 Typical Grades / Hardness

Shore D 80–90

HDT up to 120–140 °C (with proper post-cure)

Some grades offer improved chemical and fatigue resistance

6.3 Key Advantages

Suitable for under-hood, near-engine, or close-to-heat-source prototypes

Better performance for load-bearing parts

Can reduce the gap between prototype and final engineering plastics such as PA, PBT, or PC blends

6.4 Typical Applications / Parts

Automotive under-hood components (non-safety critical)

Structural brackets, levers, and housings in hot environments

Connector housings and fixtures exposed to heat

Functional tests where thermal loading is significant

7. Silicone Rubber for Vacuum Casting

Although most vacuum casting uses polyurethane, silicone rubber can also be cast for specific soft parts.

7.1 Introduce

Silicone casting materials provide excellent flexibility, temperature resistance, and stability, particularly for seals and medical or wearable concepts.

7.2 Typical Grades / Hardness

Shore A 10–60

Excellent temperature resistance from -40 °C to +200 °C (depending on grade)

7.3 Key Advantages

Excellent temperature and UV resistance

Very good biocompatibility for many grades

Stable mechanical properties over a wide temperature range

Ideal for complex shapes with deep undercuts

7.4 Typical Applications / Parts

Sealing rings, gaskets, and membranes

Medical and wearable prototypes (non-sterile, evaluation stage)

Keypads, buttons, and soft interfaces

Vibration isolation and cushioning pads

How to Select the Right Material for Your Project

When you send parts for vacuum casting, we recommend sharing the following with your supplier:

1.Functional requirements

Is the part mainly cosmetic, or must it pass mechanical/thermal tests?

2.Target production material

For example, ABS, PC/ABS, PP, PA, TPE, or silicone rubber.

The closer the target material, the more accurate the test result.

3.Operating conditions

Working temperature range, chemical exposure, UV or outdoor use.

4.Special requirements

Transparency, color matching, soft-touch, flame retardancy, biocompatibility, etc.

Based on this information, a professional vacuum casting provider can propose one or two suitable material options, including hardness range, estimated tolerances, and sample lead time.

Our Vacuum Casting Material Capability

At Kaierwo, we support a wide range of vacuum casting materials, including:

ABS-like and PC-like rigid resins (Shore D 75–86)

PP-like semi-flexible materials (Shore A 80–95 / D 60–70)

Transparent PMMA-like resins for lenses and windows

Rubber-like elastomers from Shore A 30 to 90

High-temperature engineering-grade resins up to 120–140 °C HDT

Silicone rubber for seals, cushions, and soft interfaces

For each project, we can:

Recommend material grades based on your 3D model and test requirements

Provide material data sheets on request

Support color matching and surface finishing (texture, gloss, soft-touch)

Offer measurement reports for critical dimensions

If you share your CAD files and target production material, our engineering team will help you select the most appropriate vacuum casting material and process setup.