Factors Affect the Shrinkage of Fluoro Rubber O-rings

1. The shrinkage of fluoro rubber o-rings increases with the increase of rubber content in vulcanized products.

2. With the increase of the hardness of vulcanized products, the shrinkage rate of rubber O-ring becomes saddle curve

3. The shrinkage of fluoro rubber o-rings increases with the increase of curing temperature. For every 10 degrees of increase, the shrinkage increased by 0.1% - 0.2%.

4. The shrinkage of fluoro rubber o-rings increased with the increase of raw meal injection amount of vulcanized products. When the mass of the raw meal is 5% - 10%, the shrinkage is relatively stable

5. The shrinkage of rubber material along the rolling direction and flow direction is greater than that along the vertical direction

6. The better the plasticity of the rubber compound, the smaller the shrinkage rate; the higher the hardness of the compound, the smaller the shrinkage (except high hardness)

7. The more filler was used, the smaller the shrinkage was; the higher the content of the gum, the greater the shrinkage.

8. For the mold with a porous cavity, the shrinkage rate of the vulcanized product in the middle cavity is greater than that in the edge cavity

9. The shrinkage of injection molding vulcanized products is slightly less than that of compression molding vulcanized products.

10. The shrinkage of thin products (section thickness less than 3 mm) is 0.2% - 0.6% higher than that of thick products (section thickness greater than 10 mm)

11. The shrinkage of circular and square sections of the same specification is similar.

12. The more sandwich fabrics, the smaller the shrinkage

13. The rubber O-ring with metal inlay shrinks less and shrinks to metal inlay

14. The expansion and contraction rate of fluoro rubber o-rings fluctuates widely. General fluoro rubber o-rings are vulcanized once or twice. The cavity of the first foaming vulcanization (and forming pores) decreases by about 60% according to the product size. As a type of vulcanizate, the shrinkage rate increases by 7% - 10% according to the product size, which is a variable and extremely complex problem. Mold designers also need to think carefully. At present, there is no real and perfect formula with practical value. It can only be quoted by empirical estimation or by accumulating actual measurement data. Because that is to use glue, the same mold, under the same process conditions (if the curing temperature is the same, the curing pressure is the same, and the amount of raw material is the same), the shrinkage rate is also different.

Therefore, the shrinkage of the product measured by the test is also an approximate value, which is affected by the shape, hardness, and molding process of the product. factor. Therefore, it is necessary to introduce a correction value into the average value of the measured shrinkage, and the correction direction is more than 1-14 points.