The objective of a metallurgical microscope used as a microinterferometer has been restricted to low power lens. For, it has been considered that to observe the interference fringes by high power lens is likely to involve optical difficulties.
In this experiment, the interference fringes could be observed with high lateral resolution and magnification by overcoming the optical difficulties.
The objectives used in this apparatus were × 40 lens of numerical aperture of 0.64 and × 120 lens of numerical aperture of 1.25 (Oil). Photographic interference fringes were much superior to the best ones obtained by low power lens.

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Under the principal assumption that the heat transferred by conduction in the direction of motion of chip may be neglected, the temperature distribution in chip in case of dry and wet metal cuttings is investigated by a step-by-step difference method. The relationship between the chip velocity V_f and the cooling power of cutting fluid which is represented by the heat transfer coefficient is discussed. The analysis reveals that, under the usual cutting conditions and water emulsions, the rate of temperature decrease at tool-chip interface from chip side is no more than 10% at the most, and nearly zero at more than 200 m/min of cutting velocity.

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The surface layer of electro-machined mild steel was investigated by three methods, that is etching, micro-structural and micro hardness test, and was compared with that of the same material in case of being drilled and bored.
It was confirmed that electro-machined surface layer was subjected to structure change and thermal strain due to intense and instantaneous heating and cooling by spark, and also confirmed that the immediate surface structure was changed into martensite.

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In Part 1 the mechanism of high speed machining was studied for the case where there existed no built-up-edge. In this report speed effect is examined when steel and cast iron are machined by carbide tools being compared with the case without built-up-edge (standard type). The deviation in machining characteristics from the standard type treated in Part I has been proved to be caused by the size and shape of built-up-edge with regard to the cutting speed. In short the case with built-up-edge corresponds to a modified type of the ideal or standard type which has no built-up-edge.
In addition to it, two effects of tool material and tool face roughness on the machining characteristics are also studied.

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