https://slate.com/business/2012/04/ykk-zippers-why-so-many-designers-use-them.html

Founded by Tadao Yoshida in Tokyo in 1934, YKK stands for Yoshida Kogyo Kabushikikaisha (which roughly translates as Yoshida Company Limited). The young Yoshida was a tinkerer who designed his own customized zipper machines when he wasn’t satisfied with existing production methods. One by one, Yoshida brought basically every stage of the zipper making process in house: A 1998 Los Angeles Times story reported that YKK “smelts its own brass, concocts its own polyester, spins and twists its own thread, weaves and color-dyes cloth for its zipper tapes, forges and molds its scooped zipper teeth …” and on and on. YKK even makes the boxes it ships its zippers in. And of course it still manufactures its own zipper-manufacturing machines—which it carefully hides from the eyes of competitors. With every tiny detail handled under YKK’s roof, outside variables get eliminated and the company can assure consistent quality and speed of production. (When the Japanese earthquake hit last year many supply chains were shredded, but YKK kept rolling along.)

https://www.shipmap.org/