Rubber rings are widely used in various fields, such as automobiles, machinery, electronics and other industries as seals, shock absorption are essential functional components.
Then when choosing grease to lubricate the rubber ring, we need to clarify several important issues:
1. What are the interactions between rubber and grease?
The interaction between rubber and grease can be roughly divided into two aspects: chemical action and physical action.In the physical action, grease and rubber are mainly absorbed by each other. From the appearance point of view, it shows swelling or shrinkage;Chemical action means that the chemicals in grease and rubber react with each other, fundamentally changing the physical properties of both, resulting in seal and lubrication failure.
2. The sealing function of rubber parts is divided into dynamic sealing (such as applications in cylinders and solenoid valves) and static sealing (such as oil sealing, water sealing, etc.) according to the work requirements.
a.Under the condition of dynamic sealing, the maximum allowable range of rubber swelling is 15%~25%. If this range is exceeded, it will definitely cause the part to be blocked.If it is shrinkage, when the shrinkage is 3% to 4%, it is very likely to cause seal failure, and it is best to limit it to less than 1%.
Rubber and Grease Compatibility
In lubricating grease, the base oil content is between 70% and 98%. Therefore, when examining the compatibility of rubber and grease, the influence factor of base oil is the largest.
Base oil compatibility with Common Rubber Materials is shown as below：
说明Legend
|
+
| 相容resistant |
+/-
| 部分融partially resistant |
| - | 不相容not resistant
|
| Mineral oi |
Synth. hydro- carbon |
Ester oil | Poly- glycol | Silicone oil | PFPE | Poly- phenyl ether |
| 丁晴橡胶NBR | +
| +* | +/-
| +/-
| + | + | + |
氢化丁腈橡胶HNBR/NEM | +
| + | +/- | +/- | + | + | + |
氟橡胶FPM/FKM | + | + | + | + | + | + | + |
三元乙丙橡胶EPDM | - | - | - | + | + | + | - |
丙烯酸酯ACM | + | +
| +/- | +/- | + | + | + |
聚氨酯橡胶EU/AU | + | +/- | +/- | +/- | + | + | +/- |
Functional Classification |
Model
|
Appearance |
Basic Oil |
Thicke ner |
Consistency Grade（NLGI） |
(℃)Temperature Range | Characteristic and Applications |
Special for silicone | SG300 | light yellow ointment | mixed oil | Lithium complex soap | 1 | -30~130 | Suitable for lubrication and sealing of silicone and EPDM rubber, with good material compatibility. for cable accessories, sealing ring dynamic sealing structure |
Special for nitrile rubber(NBR) | SG305A | light yellow ointment | mixed oil | inorganic | 2 | -50~150 | Special mixed base oil, no corrosion to NBR, swelling, shrinkage, low temperature resistance |
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| Material compatibility test |
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