Kensuke Kurihara

Machinability of some hexagonal metals

The machinability of 99.9% magnesium was studied and was compared with those of 99.9% cadmium, 99.5% zinc and 99.5% titanium. Cutting tests were performed under the Same condition for all the samples and had the following characteristics: cutting Speed of 65-400m/min, feed of 0.04-0.32mm/rev and cutting depth of 1 and 3mm. The following results were obtained:(1) Except titanium, cutting force was hardly affected by cutting speed. The order of the samples with respect to cutting force was shown asTi>Cd_??_Zn>Mg.(2) Chip shapes of zinc and cadmium changed gradually from a flow type to a sheared type as feed increased. However, titanium always showed a flow type of chips.(3) Cutting ratios of the samples were in the following order:Mg>Cd>Zn_??_Ti.(4) Cutting temperatures depended on the samples and were expressed in the following order:Ti>Cd_??_Zn>Mg.(5) Sensitivity of cutting temperature with respect to changes of cutting speed and feed was the largest for magnesium and the lowest for titanium.

Cutting temperature of commercial aluminum alloys

For the study of variation in cutting temperatures by the measuring techniques in the previous report, cutting tests were conducted under the following conditions:cutting speed 100-600m/minfeed 0.04-0.32mm/rev.depth of cut 1mm, 3mmThe specimens used for the tests were billets of the following 7 sorts of commercial aluminum alloys.2S, 11S, 17S, 56S, 63S, Lo-Ex, and Al-23%Si cast alloyThe following results were obtained.(1) The highest temperature measured in the former alloys was 470°C (for 580m/min, 0.32mm/rev. and 3mm) in 56S, and the lowest was 320°C (for 560m/min, 0.32mm/rev., and 3mm) in 2S.(2) The values of the temperature were arranged in descending order as follows.56S>17S>11S>63S>2S(3) The highest cutting temperatures in Al-23%Si alloy and Lo-Ex were about 480 and 410°C (both for 320m/min, 0.32mm/rev., and 1mm), respectively.(4) The rising rates of cutting temperature in the above alloys with respect to the change of cutting speed or feed were arranged in descending order as follows.With respect to cutting speed 11S>17S>63S_??_56S>2SWith respect to feed 11S_??_17S>56S>63S>2S(5) Isothermal lines were experimentally determined by cutting temperatures measured in the above 7 sorts of commercial aluminum alloys.

ON THE SO-CALLED BRITLLENESS OF ALUMINUM-INGOTS PRODUCED IN THIS COUNTRY

Directly after the production of aluminum from imported bauxite re-opened in this country at 1948, the problem arised that the aluminum-ingot thus produced is somewhat brittle, compared with the imported one of same grade of purity. The present investigation has been carried out in order to solve this Al4C3 problem fundamentally.Adding up to 1% of Na, Al2O3, Al4C3. AlN to the aluminum havingt he purity of 99.9%, 99.5%, 99.0%, respectively, the effect of these impurities on the mechanical properties of the aluminums was studied. Results obtained may be summarized as follows.Generally, with the addition of natrium, the hardness of aluminum increases, and the elongation, especially the elongation at high temperature (400°) decreases, while the tensile strength remains almost unaltered.The shock value decreases with the addition of natrium, showing, in brief, the increase in britlleness.The above-mentioned tendencies become conspicious, as to the purity of aluminum decreases.The addition of alumina (Bayer-alumina) shows very small influence on the mechanical properties of aluminum, while it makes the grain finer. With the addition of aluminum carbide, the elongation at high temperature (400°) decrease, while the mechanical properties at room temperature are almost unaltered. The increase of nitrogen makes aluminum some what britlle, showing the increase in tensil strength and the decrease in elongation.