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Tool Tipping and Economy

(By C. J. Graham , Workshop Manager, Hillside.)

“A tool is but the extension of a man's hand, and a machine is but a complex tool. And he that invents a tool augments the power of a man and the well-being of manking.”—Henry Ward Beecher.

“There is always room for improvement,” is an old adage and a true one. Its truth impresses one with particular force in these days of rapid progress, for seldom a day passes but does not witness the adoption of superior processes following upon the application of the scientific method. In the engineering industry especially, the introduction of modern methods and highly specialised machines, has simplified and increased production far beyond the expectation of the most ardent optimist of a short generation ago.

High speed steel of wonderful quality and capable of withstanding the most severe conditions met with in metal machining operations has, as a result of keen and scientific research work, been recently placed at the disposal of the employees in our workshops.

In order that advantage might be taken of the exceptionally efficient results obtained from the use of this steel (the initial cost of which is considerable), and as a means of prolonging its usefulness, a process known as tool tipping has been adopted, with great success at Hillside workshops.

After much experimenting, heavy low carbon shanks of low-priced material have been tipped successfully with high speed steel by the brazing process. (This necessitates the use of a specially prepared brazing medium.) A composite tool is thus produced, giving the high efficiency of super-quality tool steel at a low cost.

The method adopted in tool tipping is to procure the best super-high speed tool steel in sizes to suit the tools to be tipped. These pieces are ground perfectly true on one side and one edge, and then cut to length to suit the nose of the tool shank. The ends of the tool shanks are forged and machined (or ground) to produce a seating for the tip as shown in the accompanying illustration. The high speed steel tip is then placed in position on the shank, with the brazing medium between it and the shank, and it is tip-wired to secure it in position. The end of the tool is then placed in the tool hardening furnace and heated slowly to a dull red, after which the temperature is raised quickly to 2,300 deg. F. When this temperature is reached (as shown on the pyrometer) the tool is quickly withdrawn and pressure applied to the tip, which is cooled quickly by means of a cold air blast.

The tool can now be treated in the same manner as an ordinary solid tool.

Tips approximately 3in. long, 1¼in. wide and 3/8in. thick, have been brazed to shanks 2in. × 1½in., and the resultant tool tested in the new 5ft. 6in. Loudon wheel lathe by taking a 9–16in. cut with a 3-16in. feed. The results of the test equalled those obtained from solid high speed tools.

These highly successful tests have been followed by the adoption of the tipped tools for wheel lathes and planing machines. The field for their utilisation is a wide one. When it is considered that a high speed tool for the Loudon wheel lathe costs £4 10s., whilst a similar tool of low carbon steel with super-steel tip costs 17/6, the saving effected by the adoption of the method of tool tipping can be readily appreciated.

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