久久久国产乱子伦精品作者,>中文字字幕在线字幕乱码,亚洲午夜无码极品久久,亚洲Aⅴ狠狠爱一区二区三区试看

In our lives, digital products are our common products, and in the production of products, the use of digital product molds is also essential. In the appearance of the demand, the surface of the plastic mold cavity is often required to achieve the degree ···

First, due to long-term molding conditions, the waterproof ring inside the mold will be damaged, and the O-shaped waterproof rubber ring is easy to harden and crack, resulting in water leakage. Some waterproof rings are not properly installed and can caus···