Life improvement studies in segment-cut nut mold used in cold forming operations

In this thesis, it is aimed to increase the lifetime by making improvements in some processes in the production phase of the 4th station nut mold used in the cold forging process. Damage after working on the mold were examined and a plan was created for the necessary improvements. First of all, an equivalent of the same mold supplied from abroad examined and the differences were observed. Then, the processes to be worked on the existing mold were determined. The materials used in the mold are 1.2344 tool steel, 1.4140 tool steel and hard metal ''diamond'' (Tungsten Carbide)as it known in the industry. The mold also has two kinds of diamonds, front and base. Their types are CTE35 and CTE50 respectively. While CT represents Ceratizit, the supplier company, Extra Coarse (E) and Fine (F) are the grain size of the diamonds. 50 is represent twice the cobalt ratio (%25) in the tungsten carbide. Segment cutting nut mold production consist of 25 operations approximately and is one of the mold types produced longest time as a process. Within the scope of the master's thesis, 4 of these operations have been focused of for improvement and development. These are Segment cutting process applied in wire erosion benches, the plunge erosion processes used in the forming the base form, the flange form processing performed in the Cnc Turning, using different type of front diamond and finally polishing process. If the expected life increase can not be achieve, some operations were directly changed instead of operational improvements. These operation changes are using the copper with the carbide content instead of the bottom form machining in plunge erosion with the help of plain copper electrode and automatic polishing machine activation instead of manuel polishing. With the changes made, a significant increase in the life of the molds is aimed. Keywords: Cold forging, nut mold, hard metal, cobalt, wire erosion, diving erosion, white layer