First Prototype of Rotary-Arm Type Test System Using a Small Ball Probe for Determination of Cooling Characteristics of Quenchants

Quenchants should be maintained based on their cooling characteristics, measured on a daily basis at every worksite for keeping their performance. A test system for this purpose is required to be compact, convenient, and reasonable. A rotary-arm type measurement apparatus using a small ball probe, which was reported by Tawara in 1941, is recognized as a compact one with an automatic device to specify a circular motion of the probe for its transfer from furnace to quenchant as well as a subsequent cooling process. In this study, the concept of Tawara’s method was assessed by producing its prototype based on current heating and rotation devices, and also measurement and control systems. Trends obtained from limited results of the prototype were consistent with those of Tawara. Reasonable repeatability in measured cooling characteristics of polymer solutions was verified by systematical tests. Relative flow that occurs steadily around the probe by its circular motion is a unique point of this apparatus to enhance its accuracy and repeatability. After reviewing test methods using rotary-arm and ball probes, and standards for cooling characteristics of quenchants critically, contents, results, and outlooks on the prototype were described.