Effect of different cutter tip radiuses on machinability performance on plastic mold steel (1.2312)

This thesis focuses on the machinability of 1.2312 plastic mold steel, which is frequently used in industry. While the high hardness and wear resistance of steel provide great advantages for mold production, they also make it difficult to process. Therefore, the correct selection of the cutting tool geometry, especially the insert radius, is a decisive factor in terms of production quality. In particular, the insert radius is one of the basic parameters that determine both the surface quality of the workpiece and the strength of the tool in machining processes. Factors such as surface quality, cutting forces, and cutting temperature can all be severely affected by this seemingly small geometric detail. In this context, we conducted an experimental study to directly observe the effects of different end radii on 1.2312 steel. We carried out our experiments on a conventional lathe under the parameters of constant cutting speed, constant feed and depth of cut. In each test, only the radius value on the insert was changed as a variable to allow the effects to be observed in isolation. While making the evaluations, we proceeded through three key performance indicators: surface roughness, cutting temperature and cutting force measurements. First of all, it was observed that the surface quality improved markedly as the tip radius grew. However, this improvement brought with it higher cutting forces. In other words, while the surface quality increased, the resistance formed in the machining process increased at the same rate. When evaluated in terms of chip formation, an interesting balance emerged. Neither too small nor too large tip radii gave ideal results. The mid-level radii created a more stable structure in the machining process, as they allowed the chip to break in a controlled manner. In line with all these observations, we have come to the conclusion that in terms of machinability of 1.2312 steel, the "ideal insert radius" should be determined according to the process priorities rather than a fixed number. If the goal is high surface quality, tools with larger fillets may be preferred. This study provides an important roadmap, especially for technical teams responsible for determining tool selection and machining parameters in the production line. Because a detail such as tool geometry, which is often overlooked, stands out as a variable that can directly affect both the quality and the overall efficiency of the production process.