It can be proved from the experiment that the maximum speed of electric discharge saw-ing is independent of the components of work material, although the conditions of electric discharge sawing change according to the work materials.
This is explained from the following : The temperature at the electric discharged point is so high, that eroding capability has scarcely any relation with the mechanical, electrical and physical properties of the work in room temperature. And the burnt film of water glass and oxidized layer of the work are two kinds of dielectrical films necessary for the continuation of electric arc discharge.

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This paper describes how the magnitude and distribution of residual stresses in cold-rolled 4-6 brass sheets are affected by the reduction and the annealing temperature before rolling. For this purpose the residual stresses in the traverse direction as well as in the rolling direction are measured.
The results obtained are summarized as follows :
(1) The distributions of the residual stresses in the rolling direction are of the same type ; tension in the surface and compression in the inner layer.
(2) The annealing temperature of 600°, 650° and 700°C causes nearly the same residual stresses in the rolling direction.
(3) The residual stresses in the traverse direction are changed remarkably by the annealing temperature ; the stress caused by the rolling after annealing at 600°C is much greater than that at 650° and 700°C. And the type of stress distributions is oscillation type, in which compressive and tensile stresses exist alternately.
(4) The rate of reduction is almost independent of the residual stresses in both directions.

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One of the distinguished traits of CSM cutter is double radial raking of blades. Double radial raking not only directs the cutting force vector to the centre line of a cutter but also reduces cutting powers. Double radial raking forces the contact lengths between chip and blades to shorten, and it is the cause of reduction of cutting powers.

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Experimental results on the lapping of steel balls with the diameter of about 1 mm are as follows:
1. The rate of cutting in lapping steel balls is not proportional to the lapping pressure, owing to the crush of abrasives and the metallic contacts between the ball and the lap. These results are obtained when the abrasives are supplied intermittently with comparatively short intervals.
2. The optimum lapping pressure may exist when the sphericity of steel balls and the rate of cutting are considered. It is expected from the lapping mechanism that the optimum condition is variable due to the condition of lapping composition associated with diameter of the steel ball and feed interval of the composition.
3. The increasing rate of sphericity is connected with the lapping pressure. The maximum increasing rate is obtained when the grits are embedded actively into the lap and when no metallic contact occurs.
4. The rate of cutting performed with nylon lap is not different from that with cast iron lap when the lapping pressure is low. The increasing rate of sphericity is, however, almost proportional to the lapping pressure.
5. Nylon lap is effectively used for the fine finish in regard to the wear of lap, the residual stress, the sphericity, and the surface roughness of the work-piece.

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[in Japanese]

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