High precision and excellent surface finish in copper electrode applications
Hayato Tsuneoka, OSG Corporation Applications Engineer (End Mill Development Division)
The AE-LNBD-N DLC coated long neck ball end mill is the latest addition to OSG’s non-ferrous material processing end mill series. The AE-LNBD-N is designed for the milling of copper electrodes or copper tungsten electrodes used in die-sinking electrical discharge machining (EDM). Its specifications are uniquely engineered to enable the milling of beautiful copper electrodes without burrs, which is an indispensable element for today’s die and mold manufacturing that emphasizes on “high precision” and “high quality.”
The development and globalization of manufacturing technology has progressed at a rapid pace in recent years, and the same can be said for the die and mold industry. According to the International Special Tooling & Machining Association (ISTMA), the world’s die and mold production value increased by about 30 percent from 2008 to 2016. With the passage of time, Japan, which used to hold the world’s largest die and mold production value, has fallen in production value since the Lehman financial crisis in 2009, and has since given up the world’s number one position to China. On the other hand, in China, supported by a remarkable economic development and an increase in the number of automobiles produced, the production value in 2016 was estimated to be 25 billion dollars, which has almost doubled since 2008.
Copper electrode or copper tungsten electrode, which is the main target material of the AE-LNBD-N, is commonly used for the manufacturing of plastic molds. Today, most of the production of plastic dies has moved from Japan to China and other Asian countries. Even so, however, plastic dies still make up about 30 percent of the die production value in Japan, ranking second after press dies. Most of the plastic molds that require high precision are made in Japan, which offers excellent technical capabilities and quality assurance. The design of the final plastic product is becoming more complicated and smaller in recent times. As the molds are becoming “higher precision” and “higher quality,” a demand for the copper electrodes used for die-sinking EDM to become “higher precision” and “higher quality” has also increased.
“High precision” and “high quality” in copper electrodes mean high shape accuracy, little dimensional changes even after long hours of processing, excellent machined surface roughness, and being burr-free. To meet the needs of today’s electrode machining, OSG’s AE-LNBD-N is engineered with a “sharp cutting edge” that realizes excellent work surface quality, a “high ball radius accuracy” that enables high precision electrode machining, and “high durability” capability that suppresses tool wear, generation of burrs and changes in dimension even after long hours of processing.
OSG’s AE-LNBD-N DLC coated carbide end mills.
Sharp Cutting Edge
As shown in figure 1, the quality of the primary relief surface is improved compared to the competitor product. The ridgeline of the cutting edge is sharpened, and this sharpness enables the realization of excellent work surface quality.
Figure 1. Surface roughness comparison between the AE-LNBD-N and a competitor product.
High Ball Radius Accuracy
As depicted in figure 2, the AE-LNBD-N is engineered with a higher ball R accuracy than conventional products, which enables the processing of highly accurate electrodes.
Figure 2. Comparison of tolerance of the radius between the AE-LNBD-N and conventional products.
The AE-LNBD-N is coated with OSG’s DLC-IGUSS, which has high hardness and excellent wear resistance. As illustrated in figures 3 and 4, the DLC-IGUSS coating exhibits overwhelming wear resistance performance compared to CrN coating and Cr-based coating, which are often used for processing steel materials.
Figure 3. Comparison of milling length and flank wear.
Figure 4. Wear condition of ball flank after milling 420 m.
Figure 5. The AE-LNBD-N achieves good edge without burrs.
Figure 6. Comparison of dimensional change after milling more than 60 m. The AE-LNBD-N demonstrates stable machining accuracy with little dimensional change, with less than 1/10 in variation versus the conventional product.
The demand for “high precision” and “high quality” in the die and mold industry is increasing year by year, and it is expected that this trend will continue to progress in the future. With excellent accuracy and durability, the AE-LNBD-N will become a new standard in copper electrode processing.
For more information on the AE-LNBD-N DLC coated carbide end mill