Custom Urethane Products: Frequently Asked Questions

Cast Urethane Parts

Urethane can be custom formulated to achieve specific physical properties. However, with a wide variety of physical properties available for custom urethane parts and products, customers often have questions regarding the specifications and materials needed for their specific application.

To help, below is a list of frequently asked questions about custom urethane products with answers provided by the experts at PSI Urethanes.


What is durometer?

Durometer is the hardness of a non-metallic product or the gauge used to measure the hardness. The two most common elastomer durometer scales, using slightly different measurement systems, are the ASTM D2240 type A and type D scales. The A scale is for softer urethanes, while the D scale is for harder ones.


Polyester versus Polyether

The two main types of Polyurethanes are Polyester and Polyether. Each offers its own performance properties.


What is Polyester?

A chemical building block that provides good resistance to solvents as well as good mechanical properties in the final elastomer.


What is Polyether?

A chemical building block sometimes used in place of polyester that provides exceptional resilience and hydrolytic (reaction with water) stability.


What is MDI?

Methylene Di-isocyanate; A base form of urethane resin that needs non-Moca Type curatives.


What is TDI?

Toluene Di-isocyanate; A base form of urethane resin that needs Moca Type curatives.


What polyurethane material would work best for my application?

The following guide can be used to select the material most appropriate for your application.

Guideline Selection of Polyurethane
PropertyGreatestLeast
Tensile (tension) StrengthPolyesterPolyether
Tear StrengthPolyesterLow Cost Polyether
Compression SetTDIMDI
ReboundMDI PolyetherTDI Polyester
Low Temperature PropertiesMDI PolyetherTDI Polyester
High Temperature PropertiesTDIMDI
Abrasion Resistance:
..Sliding
..Impingement (colliding)
.
Polyester
MDI Polyether
.
Low Cost Polyether
Low Cost Polyether
Heat BuildupPolyetherPolyester
Hydrolysis (reaction with water) ResistanceMDI PolyetherTDI Polyester
Oil ResistancePolyesterPolyether
Heat AgingPolyesterLow Cost Polyether


What are some differences between thermoset urethane and thermoplastic urethane products?

The chart below highlights several differences between thermoset polyurethane and thermoplastic urethane products.

PropertyThermoset PolyurethaneThermoplastic Urethane
Heat ResistanceHolds up in temperatures of up to 250° without issueWill soften, deform and degrade at higher temperatures
HardnessWide range of durometers available in “A” & “D” scaleVery small range in “A” scale only
Load Bearing CapacityAbility to hold a great amount of weight per square inchUnable to hold a great deal of weight without destroying material
Abrasion ResistanceBest for abrasive applications because of its high abrasion resistance and cut resistanceWill abrade and tear in these cases

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As you can see, there is a remarkable range of urethane physical properties to choose from allowing urethane to be used across a wide variety of applications and industries.

For more information on the physical properties of urethane, be sure to check out the urethane technical brief or contact PSI today.