MMC Magazine

Craftsmen competing to show their skill with brazed tool bits

Brazed tool bits are made by jointing a carbide cutting edge to the top of the steel shank. It was about 60 years ago in 1956 that Mitsubishi Materials launched its first grooving tools. JIS B4105 stipulated strict specifications that made no distinction between forms used by different manufacturers. Performance was determined by the quality of the carbide used in the cutting edge. At that time, there were few Japanese manufacturers that could manufacture carbide. Mitsubishi Materials’ carbide had outstanding abrasion quality and excelled in defect resistance, and its superior machining performance was highly regarded by the manufacturing industry during Japan’s post-war recovery.

DG tool bits with replaceable cutting edges

When the cutting edge of a brazen bit is worn or damaged, the entire bit is changed. Because this includes the shank, it is not economical; and while the cutting edge can be polished to extend service life, highly-advanced skill is required to maintain cutting edge quality. This led the push for a high-quality, low-cost solution. That solution came in the form of tools with insert-type replaceable cutting edges made of carbide. The first such bit introduced by Mitsubishi Materials was a cam-lock type used for machining outer diameters, which the company launched in 1960.

Everyone involved in the project listened carefully to what customers around the world were looking for and learned that many were dissatisfied with combined units, which were major products for carbide tool companies at that time due to their excellent rigidity. The reason they were dissatisfied was that damage on the insert caused damage to the main body, and this resulted in the need to replace the entire unit, which was not economic at all. Modular type tools with replaceable inserts such as the DG tool bits were economic, but they were less rigid. Therefore, we decided to focus on developing a new modular-type grooving tool with rigidity equivalent to the combined unit.

Nagaya liked motor vehicles, especially motorcycles, and belonged to the auto club at his university. He continued participating in the JAF Gymkhana, a driving competition, after he started working at Mitsubishi Materials. “After the project started, I was continuously racking my brain to come up new ideas. One day when I was reading a motorcycle magazine, I saw an article on radial-mount brake calipers, which were fixed vertically rather than the standard lateral placement to increase rigidity.”

Inspired by the concept, Nagaya focused on three-directional fixation to increase durability against the force of machining: from the front and diagonally upward as well as from the side. It was called a try-lock system. “When you look at the shape, it really has a simple structure. However, we did not have grooving tools capable of fixing inserts from the front. I was excited and really wanted to commercialize this system before someone else came up with the idea.” Try-lock system development went very smoothly, and its high performance was verified using prototypes. However, the cost of manufacturing its modular blade, which had a complex form, had become a significant issue. “We applied complete machining to the prototypes; but this failed to meet time and cost requirements. I then decided to use press sintering technology that had been developed by Mitsubishi Materials. I think we were the first to succeed in using this technology to attach an insert to the main body of the tool. I also wanted a product that looked good and could be distinguished from others at a glance.” Nagaya continued: “The side of the modular blade was inspired by the thinning seen in racing car parts, a technique that provides both strength and light weight.”

Finally, the modular-type GY series realized high rigidity equivalent to the combined type. It succeeded in reducing chattering vibration for broad machining conditions and in a realizing high-quality finishing surface and long life. Since being launched in 2008, the GY series has received an overwhelming response from the market with sales quickly exceeding our competitors’ products. The technological contribution to the industry was highly regarded, and Mitsubishi Materials was recognized with the 2009 Technological Achievement Award from the Japan Cemented Carbide Tool Manufacturers’ Association (currently the Japan Cutting & Wear-resistant Tool Association). The GY series achieved its mission as the first new grooving tools that Mitsubishi Materials had introduced in 20 years. New items in the GY series scheduled to be launched in 2017 spring have been under development.

Mitsubishi Materials holds the highest number of machining tool patents among domestic tool manufacturers. It is also among the top patent holders in the world. The number of patents usually acquired for one machining tool is about 1 to 2. However, the GY series has surpassed this with an amazing 19 patents. We interviewed Koyama and Hiyama, both Managers Chief Engineers in charge of intellectual property rights about the acquisition of patents for the GY series.

When- Mitsubishi Materials began GY series development in 2004, the Research & Development Development Department’sDivision’s Koyama surveyed about 500 patents that had been acquired by other manufacturers. At the same time, the department also started examining the design drawings for the new product proposed by Nagaya’s team. “I told them,” Nagaya said, “that they needed to take extra care with any modifications to avoid the possibility of infringing patent rights held by other companies; and I was impressed with their attention to detail and ingenuity in moving forward despite this restriction. I admired their enthusiasm greatly.”

The GY series entailed the development of a wide range of small parts such as modular blades, clamp mechanisms for inserts, breakers for inserts, and applications for inner diameters and edges. “One day,” said Koyama, “we received notice that an overseas competitor had filed an objection to our application for a European patent. Although concerned, we also took it as a sign that the GY series was a growing force in the European market. The competitor claimed prior development; however, we argued that the innovative form of the GY series delivered performance that had never been achieved by other products, and our patent was granted.”

“When we were in the long, dark tunnel of patent conflict with our competitors, Hiyama and Koyama lighted the way. I really appreciated them,” said Nagaya. At Mitsubishi Materials, development staff and staff in charge of intellectual property rights share information during development. This is one of the company’s significant strengths in the development of innovative products.

“Because JIS stipulated specifications for grooving tools used for brazed tool bits, details such as form and size, performance was standardized across the industry regardless of the carbide material used. However, there were no standards specifying the form or size of inserts such as those used for DG tool bits. The individuals involved in the development of DG tool bits were excited about the opportunity to differentiate their products from competitors. The GY series products we developed were the first new grooving tools that Mitsubishi Materials had produced in 20 years. Although there was significant pressure on us to come up with products that had great potential, we were fairly free to move in our own directions. Of course, we faced a number of difficulties during development; but cooperation among the individuals in manufacturing, sales, development and intellectual property rights got us through the rough patches along the path to GY series commercialization. I can honestly say that the GY series came to fruition through the combined efforts of all employees at Mitsubishi materials, and all of us learned valuable lessons during this development project.