Boss consults, we are injection molding shell material, such as the plastic shell of mobile phone speaker, the rubber material is PC+30%GF, the product is small, and the accuracy requirements are very high. At present, Datong DHA1 is used, the hardness is HRC50, and the price is more than 60 kilograms. It is also easy to stick to the mold.
We have to hit more than 1 million molds for a pair, and it is very troublesome to repair the mold frequently. We also have some core pulls, using imported 8407 die steel, which costs more than 100 kilograms, and is not durable. Is it related to the inappropriate steel chosen? [Yuhui Mould Steel Huang Zipeng's Diary No. 776]
The glass fiber material is relatively hard, and the rubber with high glass fiber content is like a lot of small stones rubbing on the surface when the mold cavity flows, and the abrasive grain is more seriously worn. It is necessary to improve the surface hardness of the mold as much as possible so that it is not easy to be scratched.
DHA1 is the exclusive grade of Japan Daido Special Steel Company, the alloy composition is 4Cr5MoSiV1, the carbon content is about 0.38%, the hardness is HRC50, and it can be mirror-polished to No. 5000.
DHA1 can be classified as Japan SKD61 type mold steel, the alloy formula and the American standard H13, German standard 1.2344 is the same type, the main use is hot forging, die-casting mold, can also be used as a plastic mold with wear resistance requirements.
Some bosses may ask, why is the price of Datong DHA1 (SKD61) so much more expensive for the same H13 type? Why is it so expensive, and the mold is still not durable?
First of all, the pricing is determined by Datong Company, and imported die steel has always been sold at this price, which is not cheap compared to the price of domestic die steel.
Secondly, Datong's steelmaking and smelting technology has always been good, the steel has less impurities, high isotropy, and the impact toughness of hot work die steels such as DHA1 (SKD61) and DH31-EX is higher than that of ordinary H13.
If it is used in aluminum alloy die-casting mold, DHA1 (SKD61) with good smelting process and high toughness has good crack resistance and longer life than ordinary H13.
As for the short life of the injection mold used in this PC+30%GF, it is indeed the steel selected is not suitable. With glass fiber content below 20%, the life of DHA1 (SKD61) mold is still acceptable.
If you want to add 30%-50% glass fiber content, if you want to repair the mold less, you should try to have a high alloy content and use mold steel with a hardness of HRC55 or more to ensure that the mold will not be scratched quickly.
Because the boss said that he was playing black rubber material, he did not have high requirements for the polishing performance of the mold cavity, so he was recommended to use 8503 mold steel first.
The carbon content of 8503 die steel is almost twice that of DHA1, and the more carbides in the steel, the more scratched cavities. The hardness is HRC55-58, which is used for high glass fiber injection molds, and has good wear resistance. Even if you put some metal pieces together and inject them together, it won't emboss the mold quickly.
The toughness of 8503 die steel is twice as high as DC53, the same hardness is better than that of conventional cold work die steel, and it can also be mirror-polished to more than 8000, and the mold with good finish will not stick.
8503 mold steel is tempered at high temperature, the structure transformation is sufficient, the mold will not be deformed during use, and the dimensional stability is good. 8503 mold steel is more suitable for high glass fiber injection molds than DHA1, and the price is really a little more expensive than DHA1.
In the words of our boss in Ningbo: 8503 mold steel is used for plastic molds with glass fiber, which is quite nice, and there is no need to repair the mold after pressing for more than a year, and the product does not run Phifeng! Now directly PK the competitors and cover all the mold opening orders of upstream customers.
I am Huang Zipeng, from Liaobu, Dongguan. Yuhui die steel, 3 of the world's top 500 are in use, Kyocera has purchased for 7 consecutive years.
If the boss in front of the screen also has a similar speaker plastic shell PC+30%GF injection mold DHA1 erosion and wear fast working conditions, you can also come to Yuhui mold steel Huang Zipeng to try it.