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Stepping Into the Void

Aug. 12, 2009
Prehardened steel, and learning its machining limits, replaces heat treated products.
Toolox 44 is a prehardened steel said to have excellent machining characteristics due to its low carbon content and high homogeneity.

With time and resources dictating shorter production runs, fewer mold and die makers are heat treating their products. While there are certain benefits to this, such as lowering costs and shortening delivery times, it also places an emphasis on steel makers to manufacture more wear resistant and harder mold and die steels.

Swedish steelmaker SSAB Oxelosund has entered into this market by offering Toolox, a prehardened steel with an HRC of 45. Despite its hardness, the steel is said to have excellent machining characteristics due to its low carbon content and high homogeneity.

Many customers struggle initially with machining Toolox, especially in long-hole drilling (often called “gun drilling”). Longhole drilling is typically carried out in mold and die making when cooling channels are required in the tool. To develop procedures and recommendations to successfully carry out the process in Toolox, SSAB forged a technical development project with tool supplier Botek and French long-hole drilling specialist Rene Devaux.

Seeking to optimize the drilling parameters and tooling, Rene Devaux test drilled 12-mm-diameter holes to a depth of 650 mm, giving a combined total depth of 3,250 mm without any complications, and no need for resharpening the drill.

Botek made a series of tests as well, long hole drilling in 45 HRC Toolox, finding, among other things, that long hole drilling is possible, but parameters need to be individually adapted for each application. It found that no vibrations can be accepted, that coated tools with the correct carbide type are extremely important, and that it is crucial to have the recommended angle on the drill tip. The tool supplier also noted that 100% drilling oil is needed and that mixtures won’t be accepted, while holes longer than 40 times diameter need support for the drill.

At a time when mold and die makers are forced to shorten their production runs, specialty steels – and the best ways in which to tool them – become more vital than ever.

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