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 We started our factory to make hardening & tempering on spring mterial and main material is SK-4 or -5 High Carbo Steel Strips for springs. Our production process is as roughly shown below. 1. We get steel strips with wide size (I.E. 200mm) from raw material suppliers in Japan and then, cut into the necessary width in accordance with each customer's order. After packing, we send them to our China factory. 2. China factory make incoming inspection on thickness, width and surface/edge condi- tions of raw material. First production step is to make round edge to the strips and the next is hardening and tempering through electric furnace. During such process, make inspection on hardness, surface condition and so on. 3. Packing 20-30kgs in one coil by iron strips, putting oil on them to prevent rust and then, send to each customer. |
 In recent years, rolling technique on stainless steel has developed so much and extra hard material is now available. On other hand, high carbon steel strips has such weak points that they need hardening & tempering process and also need plating which often cause public polution so, stainless steel strips is more popular than high carbon steel strips for spring use. For power springs use, specs. of stainless steel is AISI-301EH. This material no need to make hardnening & tempering and has hardness of more than HV530. Afte make forming into power springs, they will be put into electric furnace to get enough spring charateristics. |