ShopSolutions Case Histories of Manufacturing Problem Solving Quick-Change Tooling Primes Pump Production L
ong job changeover times and setup scrap constantly hin- dered drive-shaft machining operations at Bosch Rexroth Corporation’s drives and controls plant in Fountain Inn, SC. The shop desperately needed to reduce setup scrap and the almost 60 minutes of downtime that occurred every time it switched from one hydraulic pump drive-shaft job to the next on its twin-spindle/twin-turret turning machines. The facility produces drive shafts in high volumes. The shafts go into its axial piston hydraulic pumps and motors used for mobile hydraulics and in the agriculture, construc- tion, mining, and material handling industries, among others. Pumps are classified according to displacement, and Bosch Rexroth manufactures a range of pump sizes/series, and each series can encompass several different shaft part numbers. Each drive shaft features a customer-specified interface type that can be a keyway or one of many spline variations. The interface is the end of the shaft that adapts to a cus- tomer’s system, while the opposite end is inside the pump and never changes. All these interface variations constitute a different part number. And these myriad part numbers within each of the different pump series mean that Bosch Rexroth is faced with frequent job changeovers. To streamline turning machine changeovers, the shop de- veloped one CNC program that would accommodate all of the different shaft part numbers. However, it realized that tooling up its turning machine turrets was a huge time constraint. So the goal was to optimize the turrets, load them with as much tooling as possible and be able to machine all the different part numbers within a shaft/pump series size with minimal, if any, tool changeover. To optimize its turning tools, Bosch Rexroth worked with Seco
Tools Inc. (Troy, MI) and incorporated cutting inserts, custom holders and Seco-Capto quick-change tooling. The Seco tooling helped Bosch Rexroth boost its tool capacity by 20% for each of the turrets in the three multitasking turning centers produc- ing drive shafts. The shop can now load up turrets with all the tools needed for a single pump size and all its associated drive shaft part numbers to reduce changeover times to less than five minutes. Plus, the tools are preset offline in the shop’s toolcrib, a
Bosch Rexroth uses a mix of Seco turning inserts, including Seco’s Duratomic type in Seco-Capto quick-change tooling to machine hydraulic pump drive shafts made from stainless steel bar stock.
practice that further speeds changeovers for operators. But more importantly, it reduces setup scrap by about 60%. Additionally, the Seco tooling allows Bosch Rexroth to run its turning operations more aggressively—in some instances with speed and feed increases of 15%. Doing so has lopped a minute off of each shaft-machining cycle time without sacrificing tool life. The Seco-Capto quick-change tooling also provides the critical repeatability needed for tooling to go directly from offline presetting operations into machine turrets so operators no longer have to perform time-consuming gage cuts that can potentially generate numerous scrapped parts. Hydraulic pump drive shafts are made from stainless steel bar stock that can be tough to cut. For the shafts, Bosch Rexroth uses a mixture of Seco turning inserts, including the
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