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Method for trimming rubber O-ring

Update:09-04-2020
Summary:

When the rubber O-ring molded product is vulcanized, th […]

When the rubber O-ring molded product is vulcanized, the rubber material will quickly fill the entire cavity, because the filled rubber needs a certain amount of interference, these excess rubber materials will flow out along the parting surface, resulting in different inner and outer diameter Thickness of glue.
Because rubber O-rings need to strictly control the quality and appearance, because their function is to seal, small rubber edges may affect the entire sealing performance, so the finished products after vulcanization also need to be trimmed, and these redundant The edge of the rubber is removed, and this process is called trimming. Generally speaking, the smaller the size, the more complicated the configuration, the higher the difficulty, and the more time-consuming and labor-intensive.

There are two methods for trimming rubber molded O-rings: manual trimming and mechanical trimming.
Manual trimming is the traditional method of trimming, by manually using a knife to gradually trim the excess rubber edge along the outer edge of the product. Higher proficiency is required to reduce the scrap rate of products. The manual trimming investment is small, the trimming quality is not high and the efficiency is low, and it is only suitable for the processing of small batches of products.
There are two methods for mechanical trimming, one is grinding wheel grinding, and the other is low-temperature freezing to remove edges.
At present, there are five methods of cryogenic freezing trimming, vibrating freezing trimming, swinging or shaking freezing trimming, drum freezing trimming, brush grinding freezing trimming and shot blasting freezing trimming.
Under certain low temperature conditions, rubber will change from a highly elastic state to a glass state, and the rubber in the glass state will become hard and brittle. The speed of hardening and brittleness is related to the thickness of the rubber product. When the O-shaped rubber ring is placed in the freezing trimming machine, the thin rubber edge of the product becomes hard and brittle due to freezing under a controlled low temperature, but the product itself will still maintain a certain elasticity. With the operation of the drum, Collisions between products, impact and abrasion of products and shot blasting, abrasives, etc., the rubber edge will be broken and fall off, to achieve the purpose of trimming. The product will restore its original performance at room temperature.
Low-temperature freezing trimming has high production efficiency and good economic benefits. However, the edge removal effect for the inner circle is poor.
The other is the grinding wheel grinding.
Put the vulcanized O-ring on the sand rod or nylon rod whose inner diameter is matched with it, and rotate it by the motor. The outer circle adopts sand paper or grinding wheel, and the excess rubber edge is removed by friction. This method is relatively simple and convenient, and the efficiency will be higher than that of manual trimming, especially suitable for products with small specifications and large batches. The disadvantage is that this kind of trimming is grinding by grinding wheel, the trimming accuracy is poor, and the grinding surface is rough.
Each enterprise needs to choose a trimming method based on its own actual situation and the size of the product, and choose it flexibly to better improve the product while reducing the scrap rate and improving efficiency.

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