Two-part polyurethane casting
A prepolymer and a curative, metered by machine at an exact ratio, poured into a heated mold, and set by chemical reaction into a solid elastomer.
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What two-part casting is
Cast polyurethane is made from two liquid components. The A side is a prepolymer. The B side is a curative. When they are combined at the correct ratio and temperature, a chemical reaction turns the mixture into a solid elastomer within minutes and brings it to full properties over the following hours.
This is different from the compression-molded, oven-baked rubber process most people picture. There is no rubber sheet, no high-tonnage press, and no giant oven. The material flows into the mold as a liquid, so it captures fine detail, fills undercuts, and bonds to metal inserts placed in the mold.
How Titan Works casts
Our dispensing machine was built to order by a Michigan engineering firm. It holds both components at temperature, degasses them, meters them at the programmed ratio, and mixes them in the head as the operator dispenses into each heated mold. Ratio and temperature are the two variables that decide whether a urethane part is good, so both are controlled by the machine rather than by hand.
Some tooling can be filled automatically. Many parts, especially those with inserts or complex cavities, pour better with an operator on the gun. We do both.
After the pour, parts gel in the mold, are demolded, then post-cure to full hardness. Trimming, deflashing, and any post-machining happen before inspection.
What the material does well
- Abrasion and tear resistance far beyond natural rubber, which is why urethane is used for wear pads and scraper blades.
- Load bearing without permanent set. A urethane bump stop returns to shape after years of hits.
- Oil, grease, and ozone resistance. Urethane does not crack and chalk the way rubber does under a vehicle.
- Wide hardness range from a soft gel to a near-rigid plastic, all from the same process.
- Bonding to inserts. Steel or aluminum sleeves, plates, and studs can be molded in.
Where it is the wrong choice
Urethane is not the answer to everything, and we will tell you when it is not. It softens above roughly 180 to 200 °F in continuous service. Some ester systems are sensitive to hot water and steam. For those cases we will point you to a different material or a different formulation.
Typical specifications
| Property | Typical range |
|---|---|
| Hardness | 40 Shore A to 75 Shore D |
| Color | Black standard, custom on request |
| Part size | Under an ounce to several pounds |
| Inserts | Steel, aluminum, brass, threaded studs |
| Tolerances | Standard cast tolerances, tighter with post-machining |
| Service temperature | Roughly minus 40 °F to 180 °F, formulation dependent |
Every program is different. Send the print and we will confirm what applies to your part.
