Experimental studies are carried out on the following points to clarify the properties of surface machined by electric discharge grinding ; roughness, hardness and wear resistance of pure iron, mild steel, S45C steel, SKH steel and sintered carbide alloy. Life test of discharge grinding carbide tool is also investigated.
The following conclusions are obtained :
(1) Surface roughness increases as electrostatic capacity of condenser increases and is independent to the discharge-frequency per unit time within the range investigated.
(2) Hardness of discharge grinding surface layer increases because of work-hardening or change of structure of metallic surface.
(3) Wear rate of discharge grinding SKH steel surface is one-half of that of the mechanical grinding surface. Wear rate of sintered carbide alloy machined by electric discharge grinding has the same degree as by diamond grinding wheel.
(4) Tool life of carbide tool machined by electric discharge grinding becomes long because the mechanical property of the surface layer of a carbide tip is improved. Face, frank and cutting edge of carbide tool machined by electric discharge grinding have a maximum height roughness of 1.5 microns.

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In this paper, relationship between the impact output by the shooting type device for measuring output energy produced by hydrospark and the equivalent static energy was discussed from the standpoint of size effect in connection with work material, die size, etc. In addition, the behavior of sheet metal under impact force and the technique for evaluating this impact energy by measuring sheet deformation caused by hydrospark were mentioned.
It was found that stability of sheet metal deformation produced by impact energy depends on work material and is in the order of copper, stainless steel, aluminum, brass, and mild steel.
Regarding relation between impact energy and its equivalent static energy, it is partially linear according to the amount of impact energy. The range of this linear relationship is different with different work material.
The relation between impact energy and its equivalent static energy is indicated by a single curve for each die size for stainless steel. Impact energy produced by hydrospark can easily be obtained from this curve by measuring sheet deformation.

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The aim of this research is to apprehend comprehensively the phenomena encountered in the shearing process which hitherto have been treated individually by many researchers. In addition, this research intends to contribute to give reasonable basis for the selection of the optimum working conditions.
Working conditions which may effect on the mode of deformation of the sheared specimen are the mechanical properties of the specimen and such restraining conditions as friction of the tool surfaces, supporting condition of the specimen and tool clearance provided that the shape of the tool and the specimen are unaltered.
The first report deals with the effect of the mechanical properties of material and lubricants on the quality of the sheared surface and shows that the process of forming the smooth portion in the sheared surface and subsequent initiation of the fracture crack is essentially influenced by the hydrostatic pressure prevalent in the material near the cutting edge.
The effect of the mechanical properties of material on the quality of the sheared surface is uniquely specified by taking work-hardening index n as a parameter.
A qualitative interpretation on the effect of each working condition on the shearing resistance is given in a consistent manner.

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This paper presents metal cutting data for the extremely high speed cutting of mild steel and aluminum alloy, each in orthogonal and oblique cutting in the high speed range, i.e.; 10008000 m/min. The influence of extremely high cutting speed on chip formation, cutting forces, and finished surface roughness, etc., have been investigated. By utilizing a tool force dynamometer and a microscope, various data are summarised as follows.
(1) On the cutting mechanism, as the cutting speed is raised, shear angle increases and the tool-chip contact length decreases, thus the machinability on chip formation is improved.
(2) At extremely high cutting speed, the cutting forces are independent of cutting speeds.
(3) With increasing cutting speed, the fine surface is obtained and the feed marks are impressed on it clearly.

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The relation between hardness deviations and the form errors of about 30 H_RC indenters in popular service in Japan is analysed. The form error of the spherical part is measured by amicroscopic collimator, so that the five parameters of form errors are obtained for each indenter with conformity to the five numerical apertures of the collimator. The angular errors of cone is obtained by an interferometer specially designed for this purpose. The conclusions of the investigation are as follows ;-
1) The observations of mean radius of curvature included in the aperture angle depend largely on the choice of aperture of the collimator. So it must be concluded that almost all indenters on the market have not geometrically spherical form at all.
2) Multiple correlation analysis can be effectively applied for testing the relation between hardness deviation and form errors of indenters, while on the other hand single correlation analysis is unavailable.
3) The results of the analysis show the existence of so large dispersion of form errors of the indenters on the market that deviations of hardness of ±1.0H_RC must be expected with significant level of 99.7%.

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This paper reports the effect of phosphate coatings and several lubricants (metal soaps, EP oils, molybdenum disulfide) for the cold extrusion of steel, concerning the reduction of the working load.
And the experiments were achieved by forward extrusion of steel bars.
The results obtained are ;
(1) Phosphate coatings were not effective in many cases.
(2) Metal soaps were generally fair or excellent.
(3) EP oils were excellent only in case of large reduction ratio for closed oil effect.
(4) Molybdenum disulfide powder was effective in second extrusion.

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