亚洲国产精品隔壁老王_国产 日韩 免费 在线 视频_av在线天堂av无码舔b_欧美老妇啪视频午夜_亚洲男人的av电影天堂_亚洲日韩一区二区三区mp4_免费现在观看国产成人AV_欧美午夜精品国产_色综合久久综合精品_永久在线 免费看黄网站

　　Corrode metal plate is also called etching plate. The main search using the mask, after etching process processing system to do three steps from the Braille metal plate or a concave metal plate.
　　Corrosion of metal plate production process:
　　1) Cutting: by drawing (layout size) in size, surrounded by more than plus not less than 5mm burrs. Shears with 720 foot-operated shears, the surface smooth, surrounded by non-Maori.
　　2) metal corrosion signs Finish:
　　(1) mechanical polishing: polishing machine with 2.2-4 kW of mechanical polishing wool, cloth round use motor speed is generally 300-350 2000-3000 revolution / min.
　　(2) alkali treatment: 10-15% aqueous solution of sodium hydroxide at 65-85 ℃ in the metal plate cook 10-30 seconds, and then washed with water, immersed in 5% of the weight of Ming acid aqueous solution.
　　(3) powder processing method: using a flat brush dipped in old powder (double pink) version of the child will be a uniform method of cross brush ears, except to effect until decontamination face, skin or remove oxygen, and then with a 5% aqueous solution of potassium dichromate In closed.
　　(4) The drawing processing method: using mechanical or manual drawing methods were brushed metal plate surface treatment, metal surface regeneration to achieve the effect.