Urethane Casting process is similar with injection molding. but the materials used for Urethane Casting is different with traditional injection molding. So before you make a cast Urethane prototype or part, it is better you know what are the materials for Urethane Casting. today, in this blog , we will share the common used materials to help you understand.
What is Urethane?
Urethane, also known as polyurethane, is synthetic polymer that belongs to the family of thermosetting plastics. Urethane contains organic chains united by carbamate links and It is formed by the reaction of polyol and isocyanate.
Is urethane a rubber or plastic?
Urethane is not exactly a plastic or rubber, alrough it have similar properties with plastic and rubber, Urethanes fill the gap between rubber and plastic.
Common Urethane Casting Materials
Common Urethane Casting Materials as below table:
|Type of Material
|urethane casting resin(Rigid)
|ABS-Like is a general-purpose polyurethane plastic that simulates ABS thermoplastic. This material is a great choice for most product enclosures.
|Shore D 76-80
|Acrylic-Like is a stiff, transparent polyurethane plastic that simulates acrylic (PMMA). This material is great for see-through applications such as light pipes.
|shore D 80
|Polytek Poly-Optic® 14 Series
|A stiff, USP Class VI, high-performance urethane with high impact strength and a HDT of 190°F (88°C).
|shore D 82-86
|urethane casting Rubber
|a polyurethane plastic that simulates all kinds of rubber-like materials such as TPE, TPU, and silicone rubber. This material is great for wearables, gaskets, and overmolds
|Clear Rubber-Like Polyurethane
|A colorless Shore A elastomer with a high elongation to break. Matte finish will give a frosted appearance, and higher gloss will increase its transparency.
|40-95 Shore A
Rigid Urethane resin
Urethane resin ABS-like is formed to duplicate the properties of ABS plastic. it can be used in urethane casting process to create parts that have good strength, durability and impact resistance like ABS plastic. for example, Hei-cast8150 is a common used ABS-like Urethane resin from Japen.
PMMA-like Urethane resin have properties similar to those of Polymethyl Methacrylate (PMMA), which is also known as acrylic or plexiglass. it is dsigned to manufacture clear parts. for example, PX5210 Casting Material from a common used French brand is a transparent material similar to PMMA (Polymethyl Methacrylate).
Polycarbonate-like Urethane is a stiff and high performance urethane with high impact strength which has similar properties as polycarbonate plastic materials. it can used for casting those parts which are orginally designed as polycarbonate materials.
flexible Urethane rubber
Rubber-like urethane resins are designed to have characteristics similar to natural rubber or synthetic rubber compounds, such as flexibility, elasticity and resilience. for example, BJB F-170 is a type of Rubber-Like Urethane materials used a lot in the market.
Mechanical Properties of urethane
there are lots of urethane materials in the market with different properties , here we take BJB TC-852 A/B as an example to show you the mechanical properties of urethane material. you will find the properties are similar to ABS plastic.
|BJB TC-852 A/B
|78 ± 2, Shore D
|Cubic Inches per Pound
|Tensile Strength (psi)
|Tensile Modulus (psi)
|Flexural Strength (psi)
|Flexural Modulus (psi)
|Shrinkage (in/in) linear
|Izod Impact, notched (ft-lb/in)
|Heat Deflection Temperature @ 66psi
|220 ± 5°F (104.4 ± 3°C)
|Heat Deflection Temperature @ 264psi
|200 ± 5°F (93.3 ± 3°C)
Benefits of Urethane Casting
- Rapid Production: Multiple components can be made within 24 hours, reducing product development time and costs.
- Cost saving: Urethane casting use silicone mold which is a cheap tooling and the Urethane resin material is also cheap compare with hard steel injection tooling.
- Design Flexibility: silicone mold do not need draft angle which can give design more room to be flexible design.
- High precision: Urethane casting can dupilicate all details of master pattern include the accurate dimensions of the master pattern made by CNC machining.
- Excellent Surface Finish: like injection molding, cast urethane parts offer excellent surface finish becasue the parts can be colored, textured and painted.
Applications of Urethane Casting
Cast urethane is often used to make a samll quantities prototypes to make some testing or other evaluation by the engineers. this mainly because the low cost and fast lead time compare with CNC machining when with a certain quantities.
Low volume production
Becasue Urethane casting is a consistent, flexible and precise manufacturing process. So when a project’s volume is low, use a hard tooling will be not a cost-effective solution, Urethane casting will be the perfect solution to balance quality and cost in terms of low volume production.
Considerations for Cast Urethane Material Selection
Choosing Urethane materials is depending on the applications of your products, there are lots of Urethane materials which have similar property with the injection molding plastic materials. So use the Urethane material which is similar with your injection modling material is the easiest way to define in the casting process. for example, In order to provide better sealant and fit, gaskets and overmolds should be made from softer, rubber-like materials.
Urethane resins are often broadly categorized according to the Shore hardness scale. “A” rating indicates softer, elastomeric materials, and a “D” rating refers to highly rigid materials. so choose the proper hardness rating according to the requirement of your applications.
KUSLA have various Urethane materials used in our plant to meet your project needs either plastic-like or rubber-like, we provide Urethane Casting service for years. Contact us today to start your projects.