Rubber Cork Gasket Material (Rubberised
Cork Sheet)
Cork in Automotive Industry
The buoyance of natural cork is used to good effect in petrol
and oil level gauges, but the most important application of
cork in the automotive industries is in cork-and-rubber
gaskets. Today, these are as essential as petrol or diesel
fuel to the car and truck industries. The material used
combine the compressibility and resilience of cork with the
high mechanical strength and dimensional stability of rubber,
making them the best substances of such automotive
applications as oil pan gaskets, valve cover gaskets and
timing gear cover gaskets.
Another important application of cork-and-rubber is as a seal
to retain lubricants in crank shaft bearings when pressure is
applied, the air within cork cells is compressed, thus
exerting a reverse pressure on the restraining faces. This is
termed 'fight back' and is a primary requirement in all good
gasket materials. Cork-and-rubber can be cut easily, and
because it is strong and flexible, it can be used for making
gaskets with narrow flanges. A wide variety of formulations
used for making gaskets with narrow flanges. A wide variety of
formulations using different types of rubber like Natural
Rubber, Synthetic Rubber, Nitrile, Neoprene, EPDM Silicone and
sizes of cork granuals are available to meet the industry's
various requirements.
Cork in Electrical Industry
Special cork-and-rubber have been developed to prevent leakage
of the very searching cooling fluids used in modern electrical
transformer, similar material are also widely used in switch
gear circuit breakers, lightning arresters, and other
transmission equipment, as well as in conduit fittings, gear
cases and cover plates in washing machines.
Rubbers cork gasket materials specification as per is - 4253
part -II 1988 ( ASTM - F-104 ).
| Mechanical
Properties |
GR/GCS-R&B
(Moderate Oil Resistant) |
GR/GCS-S&P
(Good Oil Resistant) |
GR/GCS-I&II
(Very good Oil Resistant) |
| Grade |
RC-50 |
RC-70 |
RC-80 |
RC-50B |
RC-70B |
RC-80B |
RC-50C |
RC-70C |
RC-80C |
| Hardness IRDH |
50±5 |
70±5 |
80±5 |
50±5 |
70±5 |
80±5 |
50±5 |
70±5 |
80±5 |
| Dimensional change percent
max. |
1.5 |
1.5 |
1.5 |
1.5 |
1.5 |
1.5 |
1.5 |
1.5 |
1.5 |
Tensile Strength
Kg/Cm2 (KPa*) Min. |
6.63
(650) |
9.18
(900) |
12.75
(1250) |
7.14
(700) |
12.75
(1250) |
15.50
(1550) |
12.75
(1250) |
15.50
(1550) |
19.50
(1900) |
| Compressibility at 28
Kg/Cm2 (2800 KPa) Percent |
45-60 |
35-50 |
25-35 |
45-60 |
35-50 |
25-35 |
35-45 |
25-35 |
15-25 |
| Recovery Percent Min. |
80 |
80 |
80 |
80 |
80 |
80 |
80 |
80 |
80 |
| Compression Set Percent
Max. |
80 |
85 |
90 |
80 |
85 |
90 |
80 |
85 |
90 |
Chemical Test
on water extracts
- pH where applicable
- Chloride content
(as chloride ion)
- Sulphate content
(as sulphate ion)
|
5.0 to 8.5
0.2 Percent Max.
0.2 Percent Max. |
5.0 to 8.5
0.2 Percent Max.
0.2 Percent Max. |
5.0 to 8.5
0.2 Percent Max.
0.2 Percent Max. |
| Volume change
after immersion in ASTM Oil No.3 for 70 hours at 100°C
Temp. |
40 Percent Max. |
25 Percent Max. |
15 Percent Max. |
- 1 Kg/cm2=98.0665
KPa
- Variation in thickness at
any point on the sheet is ± 10% for thickness upto 2.50 mm
and ±0.25 mm for thickness above 2.50 mm
