Non-vulcanized O-ring adhesive at high temperature, pressure for viscous fluid, and to the molding vulcanization stage, the glue quickly filled with the mold cavity, its redundant part (in order to prevent the lack of glue, filled in the mold cavity of the glue, certainly maintain a certain amount of excess) overflow vulcanization, then formed an overflow (also known as Waste edge, flying edge) Once the overflow is formed, in order to make the appearance neat, beautiful, must be removed, this process is known to repair the edge. The requirements for trimming are precise in size and neat in appearance. In actual production. Product trimming is often time-consuming, labor-intensive, for the requirements of strict products, in the trimming of a little carelessness can be out of waste, must be treated with caution. Generally speaking, the smaller the size specification of the product, the more complex the configuration, the more difficult the trimming, the more waste.