We studied the relation between cutting condition and speed of electric-discharge cutting with water-glass, and induced the mechanism of cutting.
1. The life of water-glass is long.
2. Cutting speed becomes large as the specific gravity of water-glass becomes more approximate to 1.5, but due to increasing viscosity, 1.3-1.4 may be usually preferable.
3. Several hundred gr. of the contact pressure between the work and the pole is suitable,
4. Recommendable surface speed of the pole is about 11 m/s.
5. Thinner disc is better.
6. Stronger currency is better but the effect does not increase beyond a limitation.
7. With thin works or slender works, working time is proportional to the sectional area of the works.

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This paper gives an account of experimental investigations on side force at die cutting edge in mild steel sheet blanking.
For recording the side fore : of the die cutting edge, electric condenser pick-up and special circuit devised by Mr. Inoue are employed.
The autographic recording apparatus of shearing force is contrived by the author.
The results obtained are as follows.
1. Ratio of the maximum side force at the die cutting edge to the maximum shearing force decreases gradually in proportion to the increase of the tool clearance, and these values are 0.35 at 1.5% tool clearance, and 0.33 at 19.5% clearance.
2. In less tool clearance than 5%, the maximum shearing force appears earlier than the maximum side force, but in more than 5% clearance, it is vice versa. At 5% clearance, both forces appear at the same period.
3. And others.

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How the depth of the surface layer produced on carbon steel (0.99%C) specimens by shot blasting (20 cast iron shot) and the intensity of the stress induced in the surface layer change with the blasting time was investigated.
Stress intensity was measured by applying the principle of well-known Heyn's method and the hardening effect was checked by measuring the hardness on the cross section of the specimens with micro-vickers hardness tester (200gr load).
It is confirmed that the depth of stressed layer increases up to 1.3 mm within 3.0 min. and then saturates, while the stress (compressive stress) just below the surface (in the magnitude of 0.05mm) increases rapidly up to 60 kg/mm ² within 0.5 min.and after that the increasing rate becomes small and constant.

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