Experimental investigation of specific cutting resistance for plastic mould steels

Specific cutting resistance is one of the factors which determine the machinability of the materials. This study was carried out to purpose calculating the specific cutting resistance (ks) relevant to the changes in cutting parameters experimental measurement of cutting parameters and the cutting forces occurred during machining of plastic mold steels.For this purpose, the machining experiments were performed on CNC lathe for four different plastic mold steels (DIN 1.2083, DIN 1.2738, DIN 1.2312 and DIN 1.2316). The coated and uncoated cementit carbide cutting tools which have SNMG 120408-QM form with a 75° approaching angle according to ISO 1832 were used in the experiments. Four different cutting speed (for coated tools 175, 225, 275, 325 m/dak - for uncoated tools 75, 125, 175, 225 m/dak), three different feed rate (0,1-0,25-0,4 mm/dev) and three different depth of cut (1, 1,75, 2,5 mm) were selected as cutting parameters. Cutting forces were measured by using Kistler 9257 B type dynamometer. Specific cutting force was calculated by implementing into the Kienzle equation of main cutting force values obtained based on the results of experiments.In the result of the experiments, it was determined that specific cutting resistance decreased by increasing depth of cut and feed rate for both the cutting tools. The highest value of ks was found as 3132 N/mm2 in machining with uncoated tool at 1 mm depth of cut, 0,1 mm/rev feed rate and 125 m/dak cutting speed of DIN 1.2312 plastic mold steel. The lowest value of ks was calculated as 1512 N/mm2 in result of machining with coated cutting tool at 2,5 mm depth of cut, 0,4 mm/rev feed rate and 325 m/dak cutting speed of DIN 1.2316 steel.Key Words : Specific Cutting Resistance, Cutting Force, Cutting Parameters, Turning,