Understand the ultimate precision of silicone products

When we customize silicone products, there is a tolerance for the actual size. The smaller the tolerance, the higher the accuracy, and there are many factors affecting the accuracy. The size of silicone product is too large and too small, so it is difficult to control the accuracy.How much can the ultimate precision of silicone products be achieved?

Limit size:

The thickest can be 15-20mm, if it is a sphere, the diameter can be 30mm. The thickness is generally recommended to be no greater than 3mm. When it is greater than 3mm, it will take more curing time and increase costs. The thinnest can be up to 0.2mm in theory, but in the design, the thinnest is generally 0.3mm, and 0.4mm is recommended.

Relative size:

In terms of thickness difference, it is recommended not to exceed 3 times the thinnest part and the thickest part. Such problems mainly depend on the temperature and pressure requirements of the material during vulcanization.

Shrinkage rate:

The shrinkage rate of silicone material is related to the hardness of the material. The secondary materials provided by the manufacturer are mostly between 1.022 and 1.042. For the material of 40 to 50 degrees, the shrinkage rate is generally 1.03. Compared with plastic, silicone products will not produce similar obvious surface defects due to shrinkage.

Dimensional accuracy:

Since most silicone products have multiple cavities in one mold, there are a lot of cavities compared to plastic products. Therefore, the size control is not as convenient as plastic products. The general accuracy is plus or minus 0.1mm, and the high-precision product is plus or minus 0.05mm. When the fit is used for the fit between the hole of the plastic part and the button, the minimum gap is 0.1mm on one side, and the recommended value is 0.2mm on one side.

Shape design:

For rubber sleeve parts, it is generally sufficient to provide the mold factory with the original drawing according to the product's outline drawing, and the explanation of the matching problems is left to the mold factory's own decision. Under normal circumstances, depending on the size of the product, the fit between the rubber sleeve and the product is generally a negative deviation of 0.2mm~0.5mm smaller on one side.

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