Main properties of raw materials used for enclosure gaskets
A technical choice: the gasket raw materials
The material was not chosen in regards of its price or ease of molding like gaskets made of PU foam injected through the process “Formed in place foam gasket or FIPFG “, or even of the possibility of die-cutting, but to meet the technical requirements of electrical heating applications: heat resistance, fire resistance, mechanical resistance to successive openings and closings, UV resistance.
Comparison chart of the common materials used for housing gaskets
(Compared with equivalent density of 2.4 g/cm3 and equivalent hardness of 12 to 18 Shore A)
| Material | Minimum using temperature (weakening) (ASTM D 746) |
Maximum permanent using temperature (SAE J-2236) |
Residual distortion after compression (ASTM D1056) |
Breakage mechanical resistance |
Fire resistance (UL94) |
UV resistance (SAE J1960= Automotive Industry) UL508 : boxes |
Required force for a 25% compression (ASTM D1056) |
| Polyurethan foam | -20°C | +90°C | < 5% | 455KPa (ASTM D3574, test E) | HBF (the lowest class) |
Medium deterioration | 76 kPa |
| Silicone foam | -55°C | +200°C | < 5% | 246Kpa (ASTM) D412) |
V0 and HF1 (the highest class) |
No deterioration | 27 kPa: the smallest constraint to close a lid or a window |
Average values for general comparison only as characteristics may vary from a supplier to another.