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The unproductive time in a machining operation cycle is mainly attributed to the time spent for locating the specific tools required, tools preparation, tools setting, tool
changes and the unexpected downtime due to breakdowns. Each new job requires fresh programming and tool setting. This is an unproductive work which could be outsourced as an offline operation to a seperate workstation without affecting the productivity of the machines. Even the programming of the job must be sequenced properly to reduce the time periods of tool and machine idling to the minimum possible. The downtimes could also occur if there is a problem with the supply of raw materials or if a machine breakdown occurs. The supply chain system of the tool, material inventory and the maintenance system must ensure minimum (Zero) machine
downtime. The offline programming station must be utilised to prepare the program, evaluate, fine tune the machining cycles, visually check the dryrun in 3D before machining the actual job on the NC/CNC machines. The tool setting also should be performed based on the final program with proper time tested choice of tools, allowances and spares. The use of machining centers further improve the economics by enabling simultaneous machining of more workpieces, enable performing of mutiple machining operations, offer multi-axis processing capabilities and automatic tool changes. The use of tool and job fixtures reduce the frequent fixing/ unclamping functions of workpieces greatly increasing the precision, accuracy of machining and reducing the unproductive times.
Posted by bamaji
on August 19, 2009 at 6:30 PM (Answer #1)