Some say that the history of grooving tools stretches back to 1898, when the first tool bits were manufactured. Mitsubishi Materials started producing its first grooving tool, a brazed bit, in 1956. In 1980, it developed the DG tool bit, the first bit with a replaceable cutting edge. Launched in 2008, the GY series adopted a superior clamp mechanism that dominated the market. In this feature, we trace the history of Mitsubishi Materials’ grooving tools, tools that have risen to meet the challenging needs of industry.
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.
Craftsmen at that time generally adjusted the form, rake angle and honing of brazed tool bits utilizing their grinding machines to create conditions suitable for the materials and methods being used to improve dimensional and machined surface accuracy, and extend tool life. Their skills could be judged by the quality of the tool bits they manufactured.
Brazed tool bits adopted different carbide for each material to be machined. The tail of each shank was colored differently to make it easy to ensure the right bit tool was being used for each material: blue shanks for steel, yellow for stainless, and red for cast iron. Some may still remember seeing these colorful tool bits on shelves. Currently, brazed tool bits are less common; but, they are still used to train young craftsmen.
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.
DG tool bits were launched in 1985 as grooving tools with replaceable edges.
The merits of DG bits included not only low cost and high quality, but also outstanding performance. DG tool bit inserts could be manufactured separately, which provided great flexibility in selecting carbide materials and coatings, and led to the development of high-performance inserts. These characteristics took the market by storm by enabling high-speed machining that could not be matched by brazed tool bits. A chip breaker was provided on the rake face of the insert for chip control during the manufacture of inserts using the press sintering method. This chip breaker enabled lateral machining, which had been impossible with the existing brazed tool bits. Grooving tools have improved since then to become multi-functional tools.
After Mitsubishi Materials launched its DG tool bits in 1985, other carbide tool manufacturers worked to keep pace by developing new multi-functional grooving tools. To maintain its lead against increasing market competitiveness that challenged the supremacy of DC bits, Mitsubishi Materials moved quickly to push forward with the development of new products. Hidehiko Nagaya, who was then in the Research & Development Department in charge of milling tools, was asked to head up the new-product project. “I was still fairly young at that time,” said Nagaya, “and my experience was with tools in a different area. I was surprised and happy that the company asked me to take on such a large project; but, without the experience and knowledge I felt I should have to handle the responsibility, I was also quite nervous. I accepted the challenge, though, and set my sights on doing the best job I could.”
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.
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.”
In 2006, meanwhile, Hiyama, a certified patent solicitor on staff at the Mitsubishi Materials Intellectual Property Department, was assigned to the Cutting Tool Division, which was working on GY series development. “I was worried because of past patent disputes; but Nagaya’s enthusiasm about innovation coupled with Koyama’s familiarity with cutting tool patents and the trust he had among developers made me forget my worries. Before I knew it, I was standing with them at the cutting tests.”
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.
I am currently managing a cutting tools group, so I’m away from direct involvement in development; however, I still have lots of chances to meet and talk casually with young team members in situations that allow us to dispense with form. Through our talks at such times, we seek new ideas that may have potential for development and commercialization. I’ve worked within this process of development and believe that the experience of success has a significant impact on the development of young employees; and I hope they continue the search for innovative cutting tools.”
Hidehiko Nagaya, Cutting Tools Group, Indexable Tools Development Center, Research & Development Div.