O-ring compound is a viscous fluid under high temperature and pressure. During the molding and vulcanization stage, the compound rapidly fills the mold cavity. The excess compound (to prevent insufficient filling, a certain amount of compound is always present in the mold cavity) overflows during vulcanization, forming excess compound (also called flash or burrs). Once overflow forms, it must be removed to achieve a neat and aesthetically pleasing appearance; this process is commonly known as trimming. The requirements for trimming are dimensional accuracy and a neat appearance.
In actual production, trimming is often time-consuming and labor-intensive. For products with strict requirements, even slight carelessness during trimming can result in defective products, so it must be handled with utmost care. Generally speaking, the smaller the product's dimensions and the more complex its shape, the more difficult the trimming process and the more defective products there will be.