Author : Varun Senthil 1
Date of Publication :20th November 2017
Abstract: Process improvement is the proactive task of identifying, analysing and improving upon an existing process within an organization for optimization and to meet new quotas of standards and efficiency. The part field housing cup that houses starter solenoid in tractors goes through several processes related to machining and plating. The focus is on bringing down the waste in the cold extrusion process that the part undergoes by restricting free flow of material onto unwanted runoff which is later cut off in CNC machining. Cold extrusion is a push through compressive forming process with the starting material at room temperature. In forward extrusion, the material flows in the same direction as the punch displacement and the material movement cannot be restricted in this process easily, hence a considerable amount of material is wasted as free flow in unwanted areas. The aim is to bring down this waste material by restricting unwanted material flow in cold forging process. In the forging process the material movement was initially in the direction of die and caused runoff of extra material in the direction of punch, which had to be machined out later. Restricting the material movement by minor design changes resulted in bucking of the slug and increases pressure on die and die sleeve. The extra material movement was thus restricted by redesigning the process to reverse forging where the part design was incorporated in the punch thus reducing the need to restrict material movement and also eliminating unwanted runoff. A considerable reduction in cost and reduction in material wastage was brought about in the extrusion process. There has been a 19.35% reduction in the weight of raw material from 465 grams to 375 grams and the production cost of the part was reduced by 16.15% from initial cost of Rs. 29.89 to Rs. 25.02. Several constraints and gaps in the process were addressed such as buckling of the slug, sticking of part to the punch, material waste due to extra stock material and breaking of the sleeve due to pressure of reverse extrusion. Further reforming the designs for reverse extrusion process, the stresses on the tools were also reduced (counter punch and die) which upon failure would bear very high costs. Thus a methodology was devised to restrict material run off into unwanted areas without increasing the stress on die and punch.
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