Different elastomers behave very differently. Choosing the right one before the tool is cut is the cheapest decision in the whole programme.
The widest service temperature of the elastomers we run, and the default choice for medical, food and outdoor parts.
-60 C to +250 CTwo part, injectedA two part silicone system that is metered and injected in a closed loop, for high volume precision parts.
-60 C to +250 CWeather and ozoneEthylene propylene diene rubber. The organic elastomer to reach for when a part lives outdoors or in hot water.
-40 C to +150 COil and fuelNitrile butadiene rubber. The standard answer wherever a seal meets petroleum oil or fuel.
-40 C to +108 CBalanced all rounderChloroprene rubber. Good physicals, moderate oil resistance, flame and weather resistance in one compound.
-35 C to +120 CHighest physicalsThe strongest elastomer we mould: very low compression set, high tensile strength and excellent abrasion resistance.
-50 C to +80 CChemical and heatThe material to specify when the part sees aggressive chemistry or sustained high heat.
-40 C to +240 CGas barrierVery low gas permeability and good damping, which makes butyl the sealing choice where nothing may leak through the wall.
-40 C to +120 CFDA, LFGB, ISO 13485Certified compounds, segregated production and documentation to match, for anything that touches food or a patient.
-40 C to +230 C typical for food gradeThe two groups everything below falls into.
| General purpose rubber | NR, BR, SBR, EPDM |
|---|---|
| Special purpose rubber | SR (silicone), FPM, CIIR, HNBR, CSM |
Working temperature and behaviour for the five materials we are asked about most.
| Material | Working temperature | Properties and applications |
|---|---|---|
| NBR O ring | -40 to 120 C | Good resistance to mineral oil and wear. Widely used in oil seals. Cannot be used in polar solvents such as ketones and esters. |
| SI (silicone) O ring | -60 to 250 C | Good heat and cold resistance. Inferior to other rubbers in resistance to weather, alkaline media and water. |
| FKM O ring | -40 to 240 C | Excellent heat resistance. Good oil and chemical resistance. |
| EPDM O ring | -40 to 150 C | Excellent resistance to polar solvents and weather. Poor oil resistance. |
| PTFE O ring | -100 to 280 C | Good resistance to heat, cold, chemicals and weather. One of the main materials used in low friction oil seals. Poor elasticity. |
Describe the service conditions: temperature, fluid, load, whether it is dynamic and how long it has to last. We will propose a compound and a hardness.