This article was originally published in Practical Engineering 1940 Vol1 No15. Information within this article is therefore correct as of 1940. The publication of this material aims to provide historical insight on the subject and its place in industry.
Delivery promises of drills, taps, cutters, saws, screwing dies, reamers, bits etc, have gradually been extended from two months to three month, from three months to four months and even more remote dates. Steel rationing will tend to aggravate the position. It will be useless allowing a manufacturer of armaments sufficient steel if he cannot obtain small tools for converting the steel into armaments.
There are two ways of overcoming the shortage. The first is to increase the present output of tools. This is a very costly method, involving extra plant, extra labour, extensions and all kinds of alterations not always practicable.
The second method is to make tools last longer and give greater output per regrind, and these twin objectives are being achieved to an increasing extent by the wider adoption of the Macrome treatment for cutting tools. This treatment is applied to cutting tools when they are normally regarded as ready for use. Its effect is to toughen tools throughout so that they withstand better the damaging stresses to which they are subjected. Proof of the benefits of the treatment is contained in the many reports from firms in every branch of engineering. These reports are of comparative tests carried out by the companies concerned.
A Few Typical Instances
One of the biggest shipbuilding yards in the world drilling “D” quality 7/16 in. steel using first their usual make 25/32 in. H.S.T.S. twist drills did 450 holes, the drills being badly worn. Two exactly similar drills, Macrome treated, used for the same job, did 3,600 holes before they required regrinding. Further, it was found that a Macrome treated drill, without regrinding, drilled holes in bullet proof steel at maximum speeds and feeds. Previously only low speeds and feeds could be used for this particular job, otherwise it was found impossible to drill the material.
At a famous aeroplane factory, Macrome treated screwing dies were tested. The normal output per regrind was about 1,000 components using untreated dies. A macrome treated set threaded over 7,000 components before regrinding was necessary.
On another test, Macrome treated union screwing taps ran for 42-57 days without attention, against the normal 2-3 days of untreated taps.
The treatment if carried out by Macrome, Ltd., Hay Mills, Birmingham, who will gladly arrange for a comparative test without any charge for the treatment of tools to be tested.
Image Credit: Matt Reinbold