The top 1 stainless steel screw manufacturers in China are mainly concentrated in Guangdong, Zhejiang and other places, but there are not many well-known screw factories, and the top ones are probably the following, in no particular order:
Zhejiang Dongming Screw Factory
Shenzhen Shishitong Screw Factory
Woolt China
Dongtai Huawei Standard Parts Co., Ltd.
Shanghai Standard Five High Strength Fasteners Co., Ltd.