A reaming test for cutting fluid evaluation

As an alternative to tapping torque measurement and thread finish evaluation, a reaming test is suggested for the evaluation of the lubricating efficiency of cutting fluids. An investigation was carried out where results from tapping torque measurements were compared with those from measuring torque, feed force, and surface roughness in reaming. Two different tap geometries and two different reamer geometries were used. Technically-pure aluminium was used as the workpiece material and four laboratory water-based cutting fluids as well as a commercial cutting oil were investigated. The results show that lubricants have a significant and similar effect with respect to both tapping torque and reaming torque, when tools with straight flutes are used. In reaming, a more comprehensive picture of lubrication can be obtained if torque measurement is accompanied by determination of the surface roughness. In a subsequent investigation, the reaming torque and roughness test was used to evaluate two different water-based cutting fluids and a neat oil, using austenitic stainless steel as the workpiece material.