The choice of O-ring hardness is more important. When the hardness of a power station water pump turbine is 70 (Shore) shillings, it often falls off or breaks laterally. Using 85 ~ 90 (Shore) shillings has a good effect. Low hardness makes installation easy, but it is easy to peel off, damage, protrude, and even pressure burst. The hardness of the O-ring is too high and it is inconvenient to install. Generally, the hardness of the O-ring is 40 ~ 90 IRHD, but 70 IRHD is generally appropriate in use. Silicone rubber is an exception, and 60 IRHD is generally used.

Unvulcanized O-rings are viscous fluids under high temperature and pressure. When it comes to the molding vulcanization stage, the glue will quickly fill the hollow, and the excess part (in order to prevent insufficient adhesive, the glue filling the cavity must maintain a certain amount of excess) overflows sulfur. After the overflow edge is formed by the outflowing glue (also known as waste edge, flash edge), it must be removed in order to make the appearance neat and beautiful. This process is called trimming. The trimming requirements are correct size and correct appearance. In actual production. The trimming edge of the product is often time-consuming and consuming. For products with strict requirements, trimming may be scrapped due to a little carelessness, so it should be handled carefully. Generally speaking, the smaller the size and specifications of the product, the more complex the structure, the higher the difficulty of trimming, and the more waste products.

The trimming part of the O-ring is divided into three categories: manual, mechanical, and refrigeration:

1. Manual trimming. The worker takes the tool and gradually repairs the overflow edge along the outer edge of the product. This is the original method. The efficiency is low and the quality is difficult to guarantee. In particular, the small and high-precision O-ring cannot be thoroughly cleaned, and it is easy to damage the connection between the product body and the overflow. Tooth marks and gaps are often left, leaving sequelae such as oil leakage and air leakage that affect the seal. In addition. The dependence on the proficiency of manual trimming operations is also obvious.

2. Machine trimming. In order to improve efficiency and quality, machine trimming has emerged. Common is a special electric trimming machine with a rotating blade. The blade used must be highly consistent with the product size. There is overflow on the inner and outer edges of the product. It can be designed as a double-edged edge with multiple cutting edges. It can be completed in one go. The processing accuracy of machine trimming is much higher than that of manual trimming, especially for multi-cavity products, matching tools can be designed according to the arrangement and distribution of the products. Waiting for the product to be formed. Fully covered, one-time punching is completed. With the assistance of heating, dozens of repairs can be made at a time. The key is to master the punching temperature to prevent adhesion after being too high. O-ring

3. Frozen trimming. The vulcanized finished product is de-changed together with the waste edge under refrigeration conditions. This technology was invented by Showa Carbonate in Japan and Zhaoling Precision in China. Over the past few decades, with the selection, replacement and improvement of the freezing medium and mechanical action, the freezing repair has also been improved by several generations, becoming increasingly mature and perfect, and the work efficiency and processing quality have been significantly improved.