The final results showed that the impurity levels in Yuhui’s high-toughness LG mold steel were half those of the national standard and on par with imported steel. With that, my worries were finally put to rest, and I felt relieved.
Here’s what happened: Last week, I received a “complaint” from Mr. Lan stating that the surface of the mold cores made from LG mold steel exhibited numerous pits after machining, resulting in excess material on the injection-molded products and rendering them non-conforming.
This is a long-standing client we’ve worked with for five years, so I was quite surprised to receive a quality “complaint” from him. Since LG mold steel was first launched, we had never received a single quality complaint from a customer. Naturally, I took this very seriously and immediately drove to his factory to inspect the situation on-site.
It took me just an hour to reach his factory. Under a 100x magnifying glass, the surface of the machined mold cores did indeed show pits; you could clearly see dark spots. Even when scraping the surface with a sharp-edged ejector pin, the presence of the pits was distinctly noticeable.
But to be honest, the moment I saw the actual product, I was pretty sure this wasn’t a problem with the die steel. However, I couldn’t say that outright—first, because the customer would get upset and think I was shirking responsibility, and second, because I couldn’t be so definitive without presenting evidence.
I explained to the customer that, based on what I saw on-site, it likely wasn’t an issue with the die steel. In terms of smelting quality, LG mold steel would absolutely never have such large pits.
LG’s steelmaking process utilizes a critical gas electroslag furnace, resulting in mold steel with high purity and low levels of the five major harmful impurities. The indentation in your mold is so deep that even a sharp punch can scrape it—its diameter must certainly exceed 1 mm. Mold steel produced via the electroslag remelting process would not have such a large void.
Furthermore, LG’s steel undergoes six-sided forging using 4,500-ton equipment, with three forging and three drawing passes, which significantly improves microstructural segregation and ensures uniformity. In steel that has undergone six-sided forging, large voids are broken down into numerous fine pores; even if voids exist, they are extremely small and would not exceed 1 mm in size.
If there were truly voids of that size, our non-destructive testing would have detected them, and the parts would not have been processed into finished products and shipped to you. Furthermore, since your parts exhibit numerous voids on a single surface, the steel would have undergone multiple inspections, so there is no possibility of a missed defect.
However, since your parts do indeed exhibit this issue and I cannot explain where these voids originated, there are two simple verification methods. The first is to re-polish the problematic parts. If the steel itself contains extensive sand holes, they will remain visible after mirror polishing. If they disappear after polishing, it can be concluded that the issue is not with the die steel but likely resulted from the machining process.
The second method is for me to take the part with the sand holes back to the lab, cut open the affected area, and examine the microstructure and impurity levels. This can also provide a definitive answer, but it will take a few days.
To address the customer’s concerns and assist them in making an accurate determination, the customer agreed to let me take the part back for further analysis.
After a weekend, the test results were in: Yuhui’s high-toughness LG mold steel contains half the impurities of the national standard and is on par with imported steel.
Yesterday, I explained the test results to the client, and everything became clear to him. He can now focus entirely on identifying the issue within the machining process.
The client also mentioned, “We’ve been using your materials for five years without a single problem. We’ve produced many of these parts using LG steel, and this is the only time we’ve encountered an issue. We were puzzled but didn’t know the cause, which is why we asked you to come. Now that we know the mold steel is fine, I’m relieved and can adjust the process to remanufacture the part.”
This complaint was successfully resolved, and I gained two valuable insights from the experience.
First, when handling complaints, it is essential to listen carefully to the customer’s concerns. Customers who purchase your products do so because they trust you; they would not make up issues out of thin air. Therefore, you must approach the problem with an open mind and a positive attitude. When a complaint is handled well, it strengthens the relationship with the customer, and they will trust you even more.
Second, the customer’s complaint prompted me to conduct a thorough re-examination of our mold steel. Our latest findings show that the impurity levels in Yuhui’s high-toughness LG mold steel are half those of the national standard, matching the quality of imported steel. Lower impurity levels indicate higher smelting quality, which results in a better mirror finish during polishing. This has further strengthened my confidence in LG mold steel.
Resolving a complaint successfully is a win-win situation that enhances trust in our company.
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Wu Dejian’s tool steel, the chief of staff of the user, bought everything he had used.