Nihon Keizai Shinbun 2013 August 6
Carving the “hard tool” by “tool”Using all resources, processing “ hard to cut material”.
“Hard to cut materials” such as Tungsten Carbide, Titanium alloy, Ceramics, people are trying to process by grinding effectively.
Not by one company but grinding process manufacturer, tool manufacturer and machine tool manufacturer of Japanese enterprises piled up their technology development, and finally realized its process.
Components which uses hard to cut materials normally requests high precision finish and value add is very high.
Many of domestic grinding manufacturers are working actively.
Tokyo Byora Koki Co., Ltd. (Saitama pref. Niiza city) manufacturing Tungsten Carbide press dies by machining.
Tungsten Carbide is an alloy sintered by carbonized tungsten and cobalt, it is so hard, often used for cutting tool itself.
They are carving this Tungsten Carbide by diamond coated tools or by PCD (polycrystalline diamond tool).
Forward ( Nagano prefecture, Suwa city) and Shin Nihon Tech (Osaka) are also starting cutting process of Tungsten Carbide.
So far it is known that long lifespan dies can be manufactured if they use Tungsten carbide but manufacturing process took long time as lapping must be added after EDM.
If it can be completed only by carving process from the beginning,
process time can be one third, including the fact the electrode becomes not necessary.
It is also well known by using single crystal diamond tool, carving is possible but the tool is so expensive like hundreds of thousands yen and not realistic.
One of factors which made realistic to cave Tungsten Carbide is that Union Tool Co. has started a supply of 『UDC series』tools which applies diamond coating on it in 2012.
Originally it has been developed for other purposes but it worked well with Tungsten Carbide, said Union Tool.
Price can be just 1/6 of single crystal diamond tool.
Machine tools are made by a combination of precision micro processing machine tools operated by linear motor with equipment which can adjust cutting edge position by CCD (Charged couple device) camera to micron (one millionth) meter level.
『iQ300』of Makino Milling Machine Co., Ltd. and 『μV1』of
Mitsubishi Heavy Industries Ltd. are the examples.
To those machine, the latest tools should be equipped by shrink fit so that tools should not be blurred at all.
Further, cutting process manufacturers adjust cutting depth around 1 micro meter based on their accumulated experience, and at the same time adjust number of rotations and mechanical feed rate very high in order to save wearing of tools.
Adjust tool’s moving path as linear as possible so that speed does not fall at curve.
By piling up those efforts, it is becoming realistic to cave a Tungsten carbide.
Other than Tungsten Carbide, high heat resistant Titanium alloy, Inconel and Hastelloy are hard to cave.
Specially high heat resistant alloy is hard to pass a heat and at the time of carving process heat remains at the edge of tools.
As a result, tool wears in a short time and cannot process.
Carbon Fiber Reinforced Plastic (CFRP) is also difficult to process without becoming burr and fluffy.
Cutting process manufacturers are challenging to those hard to process materials.
Machine tool manufacturers are announcing new products continuously based on new knowledge.
NS Tool Co., Ltd. has announced in May 『PCD ball end mill』
whose surface is covered with PCD.
This tool looks like there is no cutting edge.
This is designed to cave only by delicate unevenness of poly crystal diamond.
According to Mr. Matsuoka of Matsuoka Technology Institute,
who has done its development, in the case of micro process less than a micro meter unit, it is not always good if we sharpen the cutting edge. It is difficult to perform a cutting edge precisely, sharp cutting edge opt to be broken at the time of processing and temperature remain in it as a demerit.
Even cutting edge is not sharp, by high speed rotating if we reserve high mechanical feed, we can secure a good sharpness.
Sumitomo Electric Industry Ltd. and his group company A.L.M.T Corp. has announced cutting tool which uses nano poly crystal diamond 『Sumidia binder less』on February 2012.
Sumidia binder less is a nano crystal consisted by tenth nano meter diamonds and as direction of crystal is not one, it cannot be broken easily in comparison with traditional mono crystal diamond.
Its hardness is same as single crystal diamond, it is harder than any material.
According to Mr. Matsuoka, in China, high performance tool, for example the one with PCD is used at leading edge, is already in mass production.
Tool can be manufactured by CAD/CAM ( computer aided design and manufacturing) and CNC (computerized numeric control) using tool cutting board, standard levels of products can be manufactured at any country, there is a big possibility the price competition will starts.
But by adding many experience and know how, to create a new tool for hard to cut materials tools, we may avoid to fall in simple price competition.
Like S45, standard machining can be done overseas, in Japan, cutting process manufacturers and tool manufacture’s cooperation to process a hard to cut materials would be important, says Mr. Matsuoka.