S136-D can be mirror-polished to 18,000 grit, but I rarely mention it. It wasn’t until a long-time customer contacted me a couple of days ago to buy S136-D mold steel that I realized it had been a long time since I’d filmed a video like this.
He currently uses S136 mold steel for his mirror-polished molds, but he can’t achieve a clear, bright finish—it comes out hazy. Now that he can’t deliver his products, he had no choice but to come to me to buy S136-D mold steel. This time, there was no haggling over price; he simply insisted that the mirror-polished finish of the mold be guaranteed to be excellent.
The mirror-finish quality of mold steel is determined by three factors: first, the quality of the steel’s smelting process; second, its hardness; and third, the polishing technique. You can control both hardness and polishing technique, but you have no control over the smelting quality—the mirror finish is already determined the moment you purchase the steel.
If the die steel you purchase was produced using a substandard purification process—resulting in excessive or large impurities—polishing will reveal issues such as pitting, black spots, and pockmarks. If the die steel was not properly forged on all six sides, leading to poor microstructural uniformity or segregation, polishing will reveal problems such as material grain patterns, a hazy finish, inability to achieve a deep polish, and wavy patterns. Collectively, these factors are attributed to poor smelting quality.
The reason S136-D mold steel can be polished to 18,000 grit is its superior smelting quality. It is produced using a critical gas electroslag furnace, resulting in high-purity mold steel with impurity levels half those specified by national standards—on par with imported mold steel. The finer the impurities in mold steel, the better the results during mirror polishing; this is why it can achieve a mirror finish of 18,000. It is also processed using 4,500-metric-ton equipment, undergoing six-sided forging and a three-forge, three-drawing process, resulting in excellent microstructural uniformity. This ensures a crystal-clear finish during polishing, enabling it to reach a 18,000 mirror finish.
At our company, S136-D is just like DC53—we never actively promote it, yet we always have a loyal group of customers purchasing it.
If your plastic molds require high-grade mirror polishing—and the standard S136 you’re currently using doesn’t achieve a clear finish, has sand holes, pitting, or material streaks, resulting in molds that can’t be polished to a clear, bright finish and products that fail to meet customer requirements—then you should try S136-D mold steel with 18,000-grit mirror polishing.
I’m Wu Dejian, the “Mold Steel King,” from Dongguan Yuhui Mold Steel. Yuhui Mold Steel is used by three Fortune 500 companies and seven of China’s Top 500 companies; Kyocera has been sourcing Yuhui Mold Steel for seven consecutive years. If you’re unsure about which mold steel to choose, or if the mold steel you’re currently using results in short mold lifespans, and you don’t know which grade to use, then come talk to me. I’ve helped over 4,000 companies solve complex problems related to mold material selection, manufacturing, and usage. I’m confident that when it comes to selecting and applying mold steel, I can serve as your chief advisor and help you avoid costly trial-and-error.
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Wu Dejian’s tool steel, the chief of staff of the user, bought everything he had used.