Fast times

Machine tool manufacturers were producing machines designed specifically for the then-new tungstencarbidecutters in 1931, and the potential for the cutting grade was becoming evident, American Machinist editors said.

Machine tool builder Kearney & Trecker demonstrated a milling machine that featured a more rigid head and table than seen before, with a spindle that ran at speed-and feed-rates "well above average." Aluminum was machined with a 5-in. milling head at spindle speeds of 1,000 rpm (1,300 ft. per minute) with a 40 in. per minute feed rate and a 0.125-in. depth of cut. Working on a smaller cut, the machine trimmed the same piece, and demonstrated a rapid traverse rate of 240 ft. per minute. Onlookers compared the demonstration to cutting wood with a circular saw because the material was cut so fast. The machine produced an equally impressive result when it was used to cut cast iron, the editors said.