Papers by Author: Yoshihiko Murakami

Abstract: Ecological deep hole drilling is proposed in this paper. The ecological drilling means a cutting without coolant or minimum quantity lubrication (MQL). Under a cutting condition with a small amount of lubrication, the drills should be designed availably to control heat generation during cutting. An attempt is made on the development of innovative drills which are available for use under ecological cutting conditions. These drills were coated especially with a titanium aluminum nitride (TiAlN) film and a poly crystalline diamond layer. After TiAlN coating flutes of drills were lapped with diamond compounds [1]. The result of studies on the process and application of the innovative drills was reported.

Abstract: Polycrystalline diamond (PCD) exhibits a thermal conductivity similar to that of the electrically conductive chemical vapor deposition diamond (EC-CVD diamond) found to function as zero-wear electrodes at short pulse duration. In this study, PCD was used as electrodes applied to EDM on tungsten carbide. Two kinds of PCD (CTB-010 and CTH-025) with a flat surface were used. The wear of the PCD electrodes was about 1.5% for very short pulse duration such as te=1μs, but it was zero wear at te=30μs, though the wear of a Cu-W electrode was 10% even on the machine recommended conditions for the low wear. EDM experiment using a V-shaped PCD electrode with an included angle of 45° was also carried out and the performance was compared with the case using a V-shaped Cu-W electrode. Under the conditions of a no load voltage of 60V, a set peak current of 2A, and a medium pulse duration of te=15μs, there was no wear on PCD electrodes when observed under the SEM, whereas a 50μm-deep wear on the Cu-W electrodes even under the machine recommended condition for the low wear was observed.

Abstract: Electro-discharge grinding (hereafter called ED-grinding) was carried out with a trial manufactured metal bond diamond wheel containing electrically conductive diamond grits (hereafter called EC-D-grits-wheel). In this research two effects i.e. removal action of workpiece by electrical discharge machining, and an in-process dressing action of the cutting edges on the grits are expected to take place. The results of ED-grinding with EC-D-grits-wheel (f100mm, SDE120Q80M) on tungsten carbide indicated a significant decrease of 21% in the grinding force, when the set discharge current was increased from 0A to 12A. It was also clarified from the alternative-grinding test with and without an electro-discharge action that stable grinding characteristics along with a reduced grinding force could be achieved in the case of the EC-D-grits-wheel with the electro-discharge action. High-speed camera photographs indicated that a stable discharge condition was achieved.

Abstract: We would like to report on the development of our new ultra fine crystalline CVD diamond film and some applications. CVD Diamond films have good wear resistance, but the crystal size is too large. Therefore, in case of application of diamond films for cutting tools, we cannot get fine surface finish on work materials. Recently we succeed in production ultra fine crystalline CVD diamond film and various cutting tools as taps, drills and end mills. Aluminum alloys have lately been consumed more than ever in airplanes and automobiles for the purpose of decreasing the weight of structural materials.Copper alloys are used for the electrode of electric discharge machines (EDM) recently. EDM electrodes are required fine surface finish because the surface quality of mold depends on accuracy of EDM electrodes. Soft materials such as aluminum and copper alloys have high viscosity and additionally activity. So during cutting aluminum and copper alloys we have sometimes adhesion between cutting tools and work pieces. Diamond film on tools is able to improve the reactivity to aluminum and copper alloys. But up to now the diamond film has a lot of course crystal and tend to supply rough surface finish on work pieces. We developed ultra fine crystalline diamond film on end mills by plasma chemical vapor deposition (CVD) method. Now our aircraft, automotive and molding customers can get smooth surface finish of work pieces.Keeping ISO14001, we recommend oil free cutting with ultra fine crystalline diamond coated cutting tools. Here I introduce background of the development and cutting examples with new fine diamond coated end mills.