As an indicator that automakers are ramping up production levels, Kurt Manufacturing Co.’s Engineered Systems division has been tapped to deliver a series of automated custom workholding fixtures to a Tier One automotive manufacturer. The initial order, which Kurt reports is valued at $250,000, calls for 10 workholding fixtures to be integrated with robot arms into existing automated transfer lines. A second follow-on order is underway.
Kurt workholding products include multiple-station CNC vises, 5-axis vises, rotary table workholding for VMC’s, tombstones for maximum high-density workholding, and accessories for every workholding setup. It also provides a automated and manual gauging systems and is a Fanuc integrator for automation.
The newly equipped transfer lines will precision machine an automotive bearing housing, consists of two mating pieces produced from 10X8X5-in. cast iron and requires a flatness tolerance of 15 microns across the mating surface.
“The need for consistent quality along with increased production levels was the driver behind this order,” reports Jeff Lenz, Kurt Engineered Systems business unit manager. “The customer’s existing machining fixtures were not capable of clamping the parts without distorting them. Problems occurred when the assembly distorted the bearings causing abnormal operating noise and premature wear. These problems were compounded as ramped up production was planned requiring faster machining center output.”
Kurt designed two clamping fixtures for each machining center that were integrated with a robotic arm for automation. This allows for automated loading of the cast iron part, machining on all four sides, and automated unloading and stacking of the finish machined parts.
After the part is placed in the fixture by the robot, the fixture’s preload feature centers and clamps the part securely. Pressure and proximities sensors communicate wirelessly with the robot and machining center so that the entire cycle is made without the need for connecting cables and other devices. The Kurt fixture design also provides better tool access to parts during machining through the use of a special pass through “window.” This allows for cutting tools to machine on both sides of the fixtured parts at higher turning speeds, reducing cycle time to 90 seconds.
The accuracy of Kurt’s new system has been a significant improvement over the customer’s old workholding devices, which were limited to a 30-micron tolerance. By comparison, the new Kurt fixtures are capable of holding parts flat to under 12 microns while maintaining a 1.67 Cpk level.
Production output will increase, too, from 1,800 assemblies per day at present to a target of 4,500 per 8-hr shift with the new automated workholding systems added to additional transfer lines.
“We are especially excited with this order because it confirms that the automotive industry on which our economy depends heavily is rapidly improving,” reports Lenz. “We at Kurt are seeing that when a clear cut advantage can be had with our new automated workholding systems, customers like this Tier One supplier are upgrading their processes. They see good times ahead and are investing in the latest equipment to be on the leading edge of the recovery.”