WNT micro-tools are strong

Typically, micro tools have been strengthened by grinding a taper immediately behind the flutes to create a shank diameter considerably larger than the cutting diameter. The problem here is that rather this can weaken the tool, as the stress point where the angle and the flutes meet is increased. To overcome this WNT resorted to extensive Finite Element Analysis (FEM), and the research showed (using a 0.8 mm diameter cutter as an example) that having a minor diameter of 0.4 mm was the optimum, with anything above this having a negative effect on the deformation experienced by the cutter. WNT's solution to this issue was to create a large diameter radius, rather than a taper to get from the cutter diameter to the shank diameter. This reduced the stress levels on the cutter with a decrease from 3.63 MPa to 2.44 MPa when compared to traditional manufactured cutters of the same diameter. The use of a large radius, instead of a taper, has another benefit; that of increasing what is known as the aspect ratio, which is a factor of l3 (useable length):d1 (cutter diameter). WNT's Micro Mini tools are available in each size with two tool lengths and three aspect ratios, these being 2.2:1, 5:1 and 10:1. Detailed cutting data is available in the WNT September News Supplement (e-mail orders@wnt.com for your copy), or from one of its team of Technical Sales Engineers catalogue.