ACM LT (Low-temperature grade)
Grade
Pick when seals must stay flexible to −35/−40 °C; trades some hot-oil swell resistance.
Values for the LT condition
Other ACM grades and fills
ACM is listed in 11 conditions; see the grade overview at ACM.
Compare all 11 grades and fillsHide
| Grade · open for datasheet | Best for | Yield MPa | Tensile MPa | Elong. % | Hardness |
|---|---|---|---|---|---|
Shore A 50 | Choose for low-clamp-load gaskets, diaphragms and boots needing high flexibility in hot oil. | — | 8 | 330 | 12 Shore D |
Non-black / mineral-filled coloured ACM | Silica/clay-filled light-coloured compounds for identification-coded or non-marking seals; lower strength than black. | — | 9 | 250 | 70 Shore A |
LTThis page Low-temperature grade | Pick when seals must stay flexible to −35/−40 °C; trades some hot-oil swell resistance. | — | 10 | 250 | 22 Shore D |
Shore A 60 | Compromise hardness for valve-cover gaskets and moulded boots with moderate sealing loads. | — | 10 | 280 | 16 Shore D |
Active-chlorine cure-site type | Older low-cost type with good processing safety; slower cure, higher set and risk of mould/metal corrosion. | — | 11 | 260 | 68 Shore A |
A70Default Shore A 70 | Default automotive oil-seal/gasket compound; best balance of sealing force, tear and set. | — | 11 | 220 | 22 Shore D |
Heat-resistant / high-heat-stabilised grade | Choose for turbo-era powertrain seals seeing 160–175 °C oil sump peaks. | — | 11 | 200 | 23 Shore D |
Epoxy cure-site type | Ammonium-salt/acid cured epoxy type; good hot-oil ageing and moderate set, used in hoses and gaskets. | — | 11 | 240 | 72 Shore A |
Carboxyl cure-site type | Mainstream modern type: fast cure, low compression set, no metal-corroding chlorine residues. | — | 12 | 210 | 22 Shore D |
Shore A 80 | For high-pressure shaft seals and extrusion-resistant O-rings in hot oil. | — | 13 | 170 | 30 Shore D |
Shore A 90 | Back-up rings, bonded-to-metal seal cases and anti-extrusion parts; low elongation. | — | 14 | 110 | 40 Shore D |
What is ACM LT?
ACM LT is ACM in the LT grade — pick when seals must stay flexible to −35/−40 °C; trades some hot-oil swell resistance. ACM LT has a tensile strength of 10 MPa (1.38 ksi), weaker than 79% of polymer grades. Elongation at break is 250% and the elastic modulus is 0.01 GPa (7.25×10⁻⁴ Msi). ACM LT has a density of 1.25 g/cm³ (0.0452 lb/in³), heavier than 64% of polymer grades. Its glass-transition temperature is -40°C (-40 °F). A70 is the default condition FabDigit quotes; LT is available on request or by drawing note.
Advantages
- Good UV / weathering resistance — 85/100, better than 88% of polymer grades
- Ductile — tolerates forming and impact — 250%, better than 79% of polymer grades
- High service temperature — 150°C (302 °F), better than 79% of polymer grades
Limitations
- Low stiffness — 0.01 GPa (7.25×10⁻⁴ Msi), worse than 89% of polymer grades
- Difficult to machine — 30/100, worse than 87% of polymer grades
- High mold shrinkage — 2.1%, worse than 86% of polymer grades
- Absorbs moisture — dry before molding — 1%, worse than 84% of polymer grades
ACM LT properties
Typical room-temperature values for ACM LT; 17 are specific to this condition. Other listed values are ACM reference data and may not represent this condition. Bars are the position among polymer grades.
Physical3
ACM LT has a density of 1.25 g/cm³ (0.0452 lb/in³), heavier than 64% of polymer grades. Its glass-transition temperature is -40°C (-40 °F).
Mechanical10
ACM LT has a tensile strength of 10 MPa (1.38 ksi), weaker than 79% of polymer grades. Elongation at break is 250% and the elastic modulus is 0.01 GPa (7.25×10⁻⁴ Msi).
Thermal8
ACM LT is rated for continuous service to 150°C (302 °F). It conducts heat at 0.2 W/m·K (0.116 BTU/hr·ft·°F), worse than 56% of polymer grades. Thermal expansion is 200 µm/m·K (111.1 µin/in·°F).
Electrical5
ACM LT is an electrical insulator with a dielectric strength of 15 kV/mm (381 V/mil) and a resistivity of 1×10⁸ Ω·m.
Chemical & Environmental3
Corrosion resistance is very good (72/100), worse than 70% of polymer grades. UV resistance is excellent.
Sustainability4
Producing a kilogram of ACM LT takes about 110 MJ of energy and emits 5 kg of CO₂ — more than 64% of polymer grades. Typical recycled content is 0%.
Manufacturability4
ACM LT's machinability is poor (30/100, worse than 87% of polymer grades); formability very good (72/100).
Values are nominal handbook figures for design screening. Confirm any required mill or lot documentation when quoting.
Working with ACM LT
Is ACM easy to machine?
Cured ACM is die-cut, waterjet or cryogenically deflashed; conventional machining smears and is avoided.
Can ACM be welded?
Thermoset — cannot be welded; joints are made by adhesive bonding or by co-curing/bonding to metal inserts with phenolic-type primers.
Can ACM be formed, bent or molded?
Compression, transfer or injection moulded; press cure ~170–190 °C for 2–5 min plus 4 h post-cure at 150–175 °C to develop low compression set; mill mixing is sticky and needs cool rolls and processing aids.
What surface finishes work on ACM?
Post-cure removes volatiles and odour; surfaces can be PTFE- or MoS2-coated / plasma-treated on seal lips to cut friction; no painting or plating.
ACM 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 |
|---|---|---|
| cure-site monomer (carboxyl, active chlopart of the base polymer | 0.5 – 5 | 2 |
| carbon black (N550/N774)reinforcing filler; sets hardness | 20 – 45 | 30 |
| plasticizer (ester/ether type)improves low-temperature flexibility | 0 – 15 | 7 |
| curatives + accelerators (diamine/blocke | 0.5 – 3 | 1.5 |
| stearic acid / processing aids / antioxi | 1 – 5 | 3 |
| ethyl acrylate / n-butyl acrylate / methmonomer ratio sets Tg / oil-swell balance | ≥ 45 (balance) | — |
ACM LT — frequently asked
What is ACM LT used for?
ACM LT is typically used for transmission seals, valve stem seals and gaskets in hot oil environments. In short: hot-oil seal workhorse; cheaper than HNBR or FKM; 150 °C continuous in oil.
What is the tensile strength of ACM LT?
ACM LT has a typical tensile strength of 10 MPa (1.38 ksi) — weaker than 79% of polymer grades. Strength varies by condition: see the 11 listed tempers.
Is ACM LT easy to machine?
Not especially — machinability is rated poor (30/100, worse than 87% of polymer grades). Cured ACM is die-cut, waterjet or cryogenically deflashed; conventional machining smears and is avoided.
Can ACM LT be welded?
Thermoset — cannot be welded; joints are made by adhesive bonding or by co-curing/bonding to metal inserts with phenolic-type primers.
What surface finishes work on ACM LT?
Post-cure removes volatiles and odour; surfaces can be PTFE- or MoS2-coated / plasma-treated on seal lips to cut friction; no painting or plating.
Can ACM LT be formed, bent or molded?
Compression, transfer or injection moulded; press cure ~170–190 °C for 2–5 min plus 4 h post-cure at 150–175 °C to develop low compression set; mill mixing is sticky and needs cool rolls and processing aids.
What is the maximum service temperature of ACM LT?
ACM LT is rated for continuous use to about 150°C (302 °F), and briefly to 175°C. Strength falls off well before that limit — check the elevated-temperature data for load-bearing parts.
Sources
- ASTM D1418 — Rubber and rubber lattices: nomenclature — ASTM (2022)
- ASTM D2000 / SAE J200 — Classification system for rubber products in automotive applications — ASTM / SAE (2020)
- Nipol AR acrylic rubber technical data — Zeon Corporation (2022)
- Noxtite ACM / PA acrylic elastomer product guide — Unimatec (Nippon Mektron) (2021)
- Rubber Technology: Compounding and Testing for Performance — Hanser (2009)
- Handbook of Elastomers / specialty heat- and oil-resistant elastomers chapter — CRC Press (2001)
Property data is compiled from published supplier and standards handbooks and normalised for comparison. Nothing on this page is a certification — request mill certs, CoC or material test reports with your order.