General Purpose
General Purpose polyurethane is a block copolymer of MDI or TDI diisocyanate with polyester or polyether polyols and chain extenders, supplied as cast elastomer, thermoplastic TPU, microcellular or rigid foam.
Values for the GP-A80 condition
General Purpose grades and fills
General Purpose is supplied in 15 conditions, soft to hard. GP-A80 is the default FabDigit quotes; the values on this page are for it.
Compare all 15 grades and fillsHide
| Grade · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness |
|---|---|---|---|---|---|
slabstock/moulded PU foam (~30–60 kg/m³) | For cushioning, seating, packaging and acoustic absorption where load-bearing is minimal. | 0.15 | 150 | ||
closed-cell PU/PIR insulation (~30–60 kg/m³) | Best-in-class insulation core for panels, cold-chain and spray-applied insulation; not a load-bearing structural material. | 0.3 | 6 | ||
Shore A 40 | Choose for soft printing/conveying rolls, vibration pads and gaskets needing high conformability. | 18 | 700 | 10 Shore D | |
Shore A 60 | Good compromise of cushioning and load capacity for rolls, wipers and shock pads. | 30 | 620 | 16 Shore D | |
FR V-0 | Specify for cable jacketing, rail/transport interiors and electrical parts needing UL 94 V-0. | 30 | 400 | 35 Shore D | |
ESD / antistatic polyurethane | Carbon-black or ionic-additive grade for rollers, wheels and mats in electronics and explosive-atmosphere areas. | 32 | 400 | 35 Shore D | |
Lubricated / low-friction PU | Pick where sliding wear or stick-slip is the problem — dynamic seals, wear strips, guide rails. | 34 | 350 | 38 Shore D | |
Shore A 70 | Standard hardness for drive rollers, scrapers and low-noise wheels. | 35 | 580 | 22 Shore D | |
TPU polyether-based | Use where parts see hot water, humidity or microbial attack, or must stay flexible below −40 °C. | 38 | 560 | 85 Shore A | |
GP-A80Default GP Shore A 80 | Default all-round grade for rollers, pads, bushings and seals needing high abrasion and tear resistance with useful flexibility. | 40 | 520 | 30 Shore D | |
TPU polyester-based | Melt-processable grade for injection-moulded and extruded parts (hose, cable jacket, wheels) needing top abrasion and oil resistance. | 45 | 500 | 35 Shore D | |
Shore A 90 | Pick for heavy-load wheels, mill liners, cyclone parts and stripper plates where abrasion and load dominate over flexibility. | 48 | 450 | 40 Shore D | |
Shore D 60 | For structural bushings, dies, prototype tooling and stripper/forming pads that must hold shape under high load. | 50 | 300 | 60 Shore D | |
Shore D 75 | Rigid unfilled PU for machinable tooling blocks, jigs, fixtures and cast prototype parts. | 55 | 30 | 75 Shore D | |
30% glass-fiber reinforced rigid PU / RIM | Structural RIM/cast grade for stiff, dimensionally stable housings and panels replacing sheet metal. | 80 | 4 | 82 Shore D |
Supply forms, finishes and certifications
Ways General Purpose is supplied — form, process route, surface or paperwork — without a datasheet of their own. The property values above apply.
| Option | What it is | Type |
|---|---|---|
FDA | FDA / food-contact grade polyurethane | Certification |
UV | UV-stabilized / aliphatic (light-stable) polyurethane | Grade option |
What is General Purpose?
General Purpose polyurethane is a block copolymer of MDI or TDI diisocyanate with polyester or polyether polyols and chain extenders, supplied as cast elastomer, thermoplastic TPU, microcellular or rigid foam. The default condition is a cast elastomer near Shore A 80 with 40 MPa tensile strength and 520 % elongation, combining high tear strength with abrasion and oil resistance for wheels, seals, liners and coupling elements. Limits are a low service ceiling of about 80–90 °C (85 °C rated), hydrolysis of polyester types, yellowing of aromatic formulations under UV, and degradation in hot humid conditions or strong acids and alkalis. General Purpose has a density of 1.2 g/cm³ (0.0434 lb/in³), heavier than 86% of polyurethane grades. Its glass-transition temperature is -35°C (-31 °F). General Purpose has a tensile strength of 40 MPa (5.8 ksi), weaker than 60% of polyurethane grades. Elongation at break is 520% and the elastic modulus is 0.03 GPa (0.0044 Msi).
What is General Purpose used for?
- Housings
- enclosures
- fixtures
Advantages
- Ductile — tolerates forming and impact — 520%, better than 98% of polyurethane grades
- Readily welded — 15/100, better than 97% of polyurethane grades
- Good UV / weathering resistance — 35/100, better than 83% of polyurethane grades
- Forms and bends easily — 72/100, better than 75% of polyurethane grades
Limitations
- High mold shrinkage — 1.2%, worse than 97% of polyurethane grades
- Hard to polish — 30/100, worse than 82% of polyurethane grades
- Low stiffness — 0.03 GPa (0.0044 Msi), worse than 81% of polyurethane grades
- Difficult to machine — 45/100, worse than 76% of polyurethane grades
General Purpose properties
Typical room-temperature values for General Purpose-GP-A80; bars are the position among polyurethane grades.
Physical4
General Purpose has a density of 1.2 g/cm³ (0.0434 lb/in³), heavier than 86% of polyurethane grades. Its glass-transition temperature is -35°C (-31 °F).
Mechanical10
General Purpose has a tensile strength of 40 MPa (5.8 ksi), weaker than 60% of polyurethane grades. Elongation at break is 520% and the elastic modulus is 0.03 GPa (0.0044 Msi).
Thermal8
General Purpose is rated for continuous service to 85°C (185 °F). It conducts heat at 0.22 W/m·K (0.127 BTU/hr·ft·°F), better than 83% of polyurethane grades. Thermal expansion is 180 µm/m·K (100 µin/in·°F).
Electrical7
General Purpose is an electrical insulator with a dielectric strength of 22 kV/mm (558.8 V/mil) and a resistivity of 1×10¹⁰ Ω·m.
Chemical & Environmental3
Corrosion resistance is very good (80/100), better than 82% of polyurethane grades. UV resistance is fair.
Sustainability4
Producing a kilogram of General Purpose takes about 105 MJ of energy and emits 5 kg of CO₂ — more than 64% of polyurethane grades. Typical recycled content is 3%.
Manufacturability6
General Purpose's machinability is fair (45/100, worse than 76% of polyurethane grades); weldability poor (15/100); formability very good (72/100).
Common Calculations4
Values are nominal handbook figures for design screening. Certified mill or lot data ships with every FabDigit order on request.
Strength versus weight in the polyurethane family
Yield strength against density for every polyurethane grade FabDigit runs. General Purpose is highlighted; hover a dot for its name, or open the interactive family chart.
Working with General Purpose
Is General Purpose easy to machine?
Machines like a tough rubber: use very sharp positive-rake carbide or single-flute tools, high surface speed with low feed pressure, air or water-mist cooling, and support thin walls to avoid deflection and tearing; hard D-scale grades cut almost like a rigid plastic.
Can General Purpose be welded?
Cast (thermoset) PU cannot be welded — join by adhesive bonding with polyurethane/epoxy or cyanoacrylate after abrasion and primer; TPU grades weld well by hot-plate, HF/ultrasonic and hot-air methods.
Can General Purpose be formed, bent or molded?
Open-cast, centrifugal or RIM processing of prepolymer at 70–110 °C mould temperature with post-cure 8–16 h at 100 °C; TPU is injection-moulded or extruded at 185–225 °C melt and must be dried 2–3 h at 80–100 °C to avoid hydrolysis and bubbles.
General Purpose chemical composition (wt %)
Limits by weight percent from the governing specification, written the way the spec states them — a single maximum for impurities, a range for alloying elements, and the base element as balance. Nominal is the typical mid-range value.
| Element | Spec limit (wt %) | Nominal |
|---|---|---|
| MDI (4,4'-diphenylmethane diisocyanate)TDI or aliphatic HDI/H12MDI used in some grades | 20 – 40 | 30 |
| chain extender (1,4-butanediol / MOCA / sets hard-segment content and hardness | 3 – 10 | 6 |
| catalyst, antioxidant, hydrolysis stabil | 0.2 – 2 | 1 |
| glass fiber0–30% in reinforced RIM/rigid variants | ≈ 0 | 0 |
| polyester or polyether polyoladipate polyester, PTMEG or PPG; determines hydrolysis and low-temperature behaviour | ≥ 50 (balance) |
What surface finishes work on General Purpose?
Not platable or anodizable; parts are usually used as-cast or ground/lathe-finished, and can be painted with 2K polyurethane paints after solvent wipe and light abrasion — adhesion to metal cores requires blasting plus a PU bonding primer.
How much does General Purpose cost?
General Purpose is a budget-cost polyurethane ($), cheaper than about 99% of the materials FabDigit quotes. Part price depends far more on geometry, tolerance and quantity than on the raw stock — upload a CAD file for a live quote.
General Purpose — frequently asked
What is General Purpose used for?
General Purpose is typically used for housings, enclosures and fixtures. In short: everyday rigid cast PU; ABS-like feel.
What is the tensile strength of General Purpose?
General Purpose has a typical tensile strength of 40 MPa (5.8 ksi) — weaker than 60% of polyurethane grades. Strength varies by condition: see the 15 listed tempers.
Is General Purpose easy to machine?
Reasonably — machinability is rated fair (45/100, worse than 76% of polyurethane grades). Machines like a tough rubber: use very sharp positive-rake carbide or single-flute tools, high surface speed with low feed pressure, air or water-mist cooling, and support thin walls to avoid deflection and tearing; hard D-scale grades cut almost like a rigid plastic.
Can General Purpose be welded?
Not readily — weldability is rated poor (15/100). Cast (thermoset) PU cannot be welded — join by adhesive bonding with polyurethane/epoxy or cyanoacrylate after abrasion and primer; TPU grades weld well by hot-plate, HF/ultrasonic and hot-air methods.
What surface finishes work on General Purpose?
Not platable or anodizable; parts are usually used as-cast or ground/lathe-finished, and can be painted with 2K polyurethane paints after solvent wipe and light abrasion — adhesion to metal cores requires blasting plus a PU bonding primer.
Can General Purpose be formed, bent or molded?
Open-cast, centrifugal or RIM processing of prepolymer at 70–110 °C mould temperature with post-cure 8–16 h at 100 °C; TPU is injection-moulded or extruded at 185–225 °C melt and must be dried 2–3 h at 80–100 °C to avoid hydrolysis and bubbles.
What is the maximum service temperature of General Purpose?
General Purpose is rated for continuous use to about 85°C (185 °F), and briefly to 120°C. Strength falls off well before that limit — check the elevated-temperature data for load-bearing parts.
How much does General Purpose cost?
General Purpose is a budget-cost polyurethane ($), cheaper than about 99% of the materials FabDigit quotes. Part price depends far more on geometry, tolerance and quantity than on the raw stock — upload a CAD file for a live quote.
Can FabDigit make parts in General Purpose?
Yes — General Purpose is available for urethane casting with instant online pricing. Upload a STEP file to get a price and a DFM check.
Sources
- ASM Engineered Materials Handbook, Vol. 2: Engineering Plastics — ASM International (1988)
- Polyurethane Handbook (Oertel) — Hanser (1994)
- Desmopan / Texin TPU product datasheets — Covestro (2023)
- Adiprene / Vibrathane cast prepolymer selector guides — LANXESS (Chemtura) (2022)
- Elastollan TPU material properties brochure — BASF (2023)
- CAMPUS plastics database — TPU records — CWFG (2024)
- ASTM D412 / D624 / D395 / D2240 rubber test methods — ASTM (2022)
Property data is compiled from published supplier and standards handbooks and normalised for comparison; hardness values on non-Brinell scales are converted approximately for charting only. Manufacturability limits are FabDigit quote-engine defaults and may be relaxed by engineering review. Nothing on this page is a certification — request mill certs, CoC or material test reports with your order.