Custom Urethane Molding

Urethane Production Capability

Ro-Lab can bond urethane to a wide variety of metal sub-surfaces such as aluminum, brass, and steel. Urethane is ideal for making a block mold. Block molds have the advantage that they are quick to make and usually do not require a rigid mother mold like latex does.

Ro-Lab has the press capacity for small, high-volume production as well as production of large-scale parts:

  • 23 presses
  • 5-250 ton capacity
  • Platen sizes up to 24-inch by 24-inch
  • Oven capacities to 2,880 cubic feet (20-ft. by 12-ft. by 12-ft.)
  • Part sizes: less than 1 oz. to 500+ lbs.
  • Metered Mixing: up to 40 lbs./min.

Urethane Molding Processes

Urethane Compression Molding: Liquid polyurethane is poured into a mold and cured in a compression press with capacities up to 250 tons. This technique is most suitable for components that must maintain dimensional accuracy and repeatability.


  • Dimensional precision and repeatability
  • Capable of being very flexible or very rigid
  • Very durable and wear-resistant

Urethane Low Pressure Injection Molding: Injection of liquid polyurethane into a closed mold under low pressure, in a process ideal for projects in which a component size, component shape or tooling configuration would make compression molding impractical.


  • Ideal for unusual sizes or shapes
  • High precision and intricate parts
  • Finish is minimized

Open Cast Urethane Molding: The pouring of liquid polyurethane into an open mold, which is then cured in an oven or on a heated table. Usable on part sizes from less than an ounce to more than 500 lbs. Excellent for projects where conventional tooling would be expensive or impractical.


  • An economical alternative to conventional tooling
  • Low cost tooling: a mold capable of handling high pressure is not required, soft tooling may be made out of urethane or silicone
  • Suitable for smaller production runs
  • High performance product

RIM (Reaction Injection Molding): Reaction Injection Molding is the injection of polyols and isocyanates into a closed mold, triggering a chemical reaction that causes the material to expand and form the finished product.


  • Effective in forming extremely large products with very light weights
  • Able to improve or eliminate secondary operations
  • Eliminates sink marks
  • Workable for flexible or rigid products in foams or solids
  • Delivers reliable control of components with varying wall thicknesses

Polyurethane 101

What is cast polyurethane? Cast polyurethane is a polymeric material created by a combination of polyols and diisocyanates that, when extended by various curatives, produces materials with a dynamic array of properties tailored to a wide range of applications.

Polyurethane materials offer a dynamic array of properties which can be tailored to a very wide range of applications. They are a great alternative choice to plastics, traditional rubber and metals because they embody characteristics of each. Cast polyurethane can be produced to resist chemicals, water, impact, shearing, tearing and wide range of temperatures or other hazards which can cause failure in other materials.

Tensile & Tear Strength – In general, polyurethanes have a high tensile (tension) and tear strength compared to other elastomers which makes polyurethane more resilient in harsher elements and more abrasive work conditions.

Advantages Resistances
Lightweight Abrasion
Noise Reduction Impact
Hardness Flexibility Shearing/Tearing
Cost Efficient Atmospheric (Oxygen/Ozone/UV)
Metal Bonding Temperature
Machinability Water
Varied Coefficient of Friction Chemicals
High Tensile & Tear Strength Corrosion

Polyurethane Advantages

Consider Polyurethane over plastic, metal or rubber, to improve your design.
Polyurethane is a surprisingly versatile material that can bring a solution to your most challenging design applications.  It offers load bearing capabilities, abrasion resistance and impact absorption in a single material, which may be preferable compared to using plastic, metal or rubber (see below).  In many instances, it can produce significant cost savings by eliminating coating or painting, expensive tooling or machining operations.  Some tooling is required, but is often much easier to produce than the tooling required for the other materials.

Polyurethane Advantages over Plastic:

  • Lower Tooling Costs
  • Faster and Better Prototype Accuracy
  • Higher Wear Resistance
  • Higher Durability

Polyurethane Advantages over Metal:

  • More Cost Effective
  • Lighter in Weight
  • Faster Lead Time
  • Elevated Corrosion Resistance

Polyurethane Advantages over Rubber:

  • More Cost-Effective
  • Low-pressure Tooling
  • Higher Load-Bearing Capacity
  • Higher Wear Resistance

Compare Properties

Property Polyurethane Nitrile Rubber Neoprene Rubber Natural Rubber SBR Butyl
Tensile Strength (MPa) 20.7 to 65.5 13.8+/- 20.7+/- 20.7+/- 18.8+/- 18.8+/-
Durometer 5A to 85D 40 to 95A 40 to 95A 30 to 90A 40 to 90A 40 to 75A
Specific Gravity 1.10 to 1.24 1.0 1.23 0.93 0.94 0.92
Tear Resistance Outstanding Fair Good Good Fair Good
Abrasion Resistance Outstanding Good Excellent Excellent Good-Excellent Good
Compression Set Good Good Fair-Good Good Good Fair
Rebound Very High to Very Low Medium High Very High Medium Very Low
Gas Permeability Fair-Good Fair Low Fair Fair Very Low
Acid Resistance Fair-Good Good Excellent Fair-Good Fair-Good Excellent
Aliphatic Hydrocarbons Excellent Excellent Good Poor Poor Poor
Aromatic Hydrocarbons Fair-Good Good Fair Poor Poor Poor
Oil and Gas Resistance Excellent Excellent Good Poor Poor Poor
Oxidation Resistance Outstanding Good Excellent Good Good Excellent
Ozone Resistance Outstanding Fair Excellent Fair Fair Excellent
Low Temperature Resistance Excellent Good Good Excellent Excellent Good

Durometer (Hardness) Scales:

Relevant Resources