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any industry involves seal protection, this method is one of the processes of many of our items are short of one cannot, and silica gel seal protection articles category mainly to the functional role, so it is only for the use of the products, features, and performance requirements, and we all know that the silicone gasket mainly took the clamping force and the support of good protection, so the material shrinkage control nature is very important, so a lot of people when the design for the size of the silicone seal washing shrinkage but don't know how to finalize the design, mainly method didn't find it.
the silicone seal shrink how to control the size.
1。 Silicone seal washing shrinkage is along with the vulcanization silicone material density increases with the amount of gel, usually normal to zero. 0013年
2。 Silicon rubber sealing ring shrinkage is also with the hardness increase of silicone raw materials into the saddle type contraction curve changes
3. Silicone ring shrinkage with silica gel processing factory machine vulcanizing temperature increase, with the rising of temperature rise every 10 degrees, shrinkage increased 0. 1% - 0. 2%
4. shrinkage is also increase with the increasing injection rate and raw material, when raw material quality & gt; The quality of the product 5% 10%, shrinkage is relatively stable
5. Rubber calender direction and fixed in the mold shrinkage rate is greater than the vertical direction of the flow direction of shrinkage rate
6. Rubber plasticity, the better, the smaller the shrinkage; Rubber hardness is higher, the smaller the shrinkage
7. The more dosage of filler, the smaller the shrinkage; Rubber content, the higher the greater the shrinkage
8. Porous cavity mould, intermediate shrinkage cavity vulcanization silicone products is bigger than edge shrinkage cavity sulfide products
9. Injection pressure curing products shrinkage rate is smaller than sulphur products of compression molding shrinkage rate
10. Thin products, The section thickness is less than 3 mm) Shrinkage rate than thick products ( Section above 10 mm) The shrinkage rate of 0. 2% - - - - - - - - - - - - - 0. 6%
11。 With specifications of the circular cross section and cross section shrinkage rate of the approximate
12. The more laminated fabric, shrinkage rate is smaller; qz' p9O ( j4a6r + d。 m
13。 Lined with silicone O ring inlaid metal products smaller shrinkage rate, and shrinkage in the direction of the metal inlay
14. The expansion of the foaming silicone o-rings in shrinkage range is very large, foaming silicone ring generally adopts the primary or secondary sulfide, foaming sulfide (for the first time And into a hole) Mold cavity according to the size of products and small shrinkage is about 60%, according to the size of products amplified 7% - for the second time 10% as finalize the vulcanized rubber shrinkage is a changing, complex problems, and is the most the problem need to be careful consideration mold designers, at present, is not a true, complete, practical calculation formula, has only to rely on experience or through the accumulation of actual measurement data as a reference.
because even if is to use a rubber, the same picture of the mold, in the same process conditions of three-dimensional network technology BBS: Q" p; _ + v。 z4S8Y ( Share the same such as curing temperature, curing pressure, in the same amount of raw materials) The sulfide have different shrinkage rate
so to test the shrinkage rate of the goods of measuring is an approximation, plus products shape, hardness, molding process, the influence of such factors as therefore need to test the shrinkage rate of average, the revised is introduced in correct direction according to the above 1 - 14 points
flash thickness and quality of semi-finished products ( Raw material add amount) And sulfide stress, hardness, rubber mold structure has a direct relationship,
raw add quantity, the more products the thicker the flash, the vulcanization pressure is higher, products flash the thinner, the higher the rubber hardness, products flash is thicker, the piece of products when calculating the open mold shrinkage in the direction of test to the thickness of the flash operation.
3. Vulcanizing machine hot plate size to mold size
1. Mold size shall not be less than too much hot plate size, such easy to cause the hot plate deformation
2. Mold cavity edge should be within 70% of hot plate size type o sealing ring
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