The use of S136 mold steel for injection molding PVC is a material selection error. The mold is bound to rust, and electroplating is also useless.
A netizen asked, “I am making PVC hard material, and the S136 I used to use didn’t work. The mold rusted and pitted, and it rusted while polishing. It doesn’t work much. What kind of mold steel do I need?
The chlorine gas generated during PVC injection molding causes severe corrosion to the mold. Mold steel with low carbon chromium ratio has poor corrosion and rust resistance, making it easy to corrode and rust. When injecting PVC, most people use the wrong mold steel.
The use of S136 mold steel for injection molding PVC is a material selection error, and it is normal and inevitable that the mold is prone to rusting. S136 is an air type stainless steel with a carbon C content of 0.38% and a chromium Cr content of 13%. It has a low carbon chromium ratio and poor stability of the passivation layer, which cannot resist the corrosion of PVC on the mold and is prone to rusting. Even chrome plating is useless. He is rusting and polishing at the same time, which proves this point.
This passivation layer is equivalent to a protective film on the surface of the mold. The higher the chromium Cr content of the passivation layer, the better its stability and rust prevention performance.
For injection molded PVC, I recommend Yuhui M316 mold steel with high carbon chromium ratio and strong corrosion resistance.
M316 is a super stainless steel exclusive to Yuhui Mold Steel, with a chromium Cr content of 16% and a high carbon chromium ratio. The passivation layer on the surface of the mold has a high chromium Cr content and good stability, which will not be penetrated by corrosive media, thus providing strong corrosion and rust resistance. Trace elements are added to further enhance the stability of the passivation layer. Even if PVC is injected, the mold will never rust, and the mold will become brighter and brighter with quenching hardness of 50-54HRC. It is also an electric slag steel with high purity. It has undergone 4500 tons of equipment six sided forging, three forging and three drawing, with good organizational uniformity. M316 with good smelting quality can be mirror polished to 10000~12000. The rust problem that cannot be solved by S136 is never rusted with M316 mold steel. The more it is made, the brighter it becomes, and there is no need for electroplating.
Mr. Zhou from Zhuhai injected PVC suction cup lens products. The original mold core used S136H mold steel, which could not produce many products. As a result, the mold corroded and lost its luster, leading to the appearance of wrinkles and shadows. Electroplating is also useless, it just extends the lifespan by two more days. Even after two more days, it will still corrode and require continuous polishing. The product does not meet customer requirements and is constantly complained by the devil.
But when using M316 mold steel, he said the mold became brighter and brighter as he made it. He has already injected more than 300000 products, and the guy really likes it. Previously, due to constant electroplating and frequent polishing, the sealing effect of the suction cup was not good, and the flat surface became convex. Now, M316 mold steel has been used to solve the problem in one go. It does not rust or require electroplating, and the mold is becoming brighter and brighter. Guilao really likes it. Thank you for your good recommendation.
So the netizen injected PVC hard material, and the S136 mold is prone to rusting. The pitted areas rust while being punched, and polishing them is useless. I recommend using M316 mold steel.
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Wu Dejian’s tool steel, the chief of staff of the user, bought everything he had used.