Oxnard, California: No one knows precision machining better than Haas Automation. As the largest CNC machine tool builder in the Western World, Haas naturally would implement only the most productive and highest quality processes in its own machining operations.
Recently, Haas phased in an automated machining cell using a new model Kurt workholding setup with capacity to increase output by two to three times, according to Phillip Linscheid, machine shop manager at Haas Automation.
"The goal with the new workholding setup was to automate the milling operations used to produce our machining center spindle shafts in a cell with two lathes and a milling machine tended by a Motoman Hp 165 robot," Mr. Linscheid reported. "The robot provides the load/unload operations for each of the three machines. There is no fixture set-up labor required. The cell operates automatically during the 8-hour day shift and continues to run unattended through the night. We're operating continuously 20 to 21 hours a day with this new cell depending on quantities required. We're achieving two to three times greater output for different size spindle shafts versus the previous setup. We're able to get that kind of productivity increase without needing a machine operator for the nighttime hours."
Repeatable 0.001 Inch Clamping Accuracy And Up To 6000 Lbs Clamping Force
Mr. Linscheid reported that its new Kurt Double Acting Hydraulic vise gives Haas the automated and repeatable clamping needed in the cell setup. Using hydraulic pressure, the new double-acting design ensures that the moveable jaw opens and closes precisely with up to 6000 lbs clamping force actuated by the machining center's computer numerical control programming.
(Single acting hydraulic clamping devices close with hydraulic pressure but utilize a less precise spring mechanism for reopening so they aren't designed for automated CNC machining setups.)
To facilitate automated part handling, the machining centers and robot are preprogrammed with the correct load/unload position. To begin, the machining center positions the fixture in the load position and the robot inserts the workpiece into the vise jaws which then clamp the part. The robot exits the machine and the machining cycle begins. When machining is completed, the robot moves back into position, grasps the finished part as the vise jaw opens.
The robot moves and stacks the part in an offload station. The cycle repeats itself with the robot picking up a new workpiece for placement in the vise jaws.
Kurt Vise Clamps Rigid For +.005 - .000 Machined Tolerances
The new Kurt vise is mounted vertically on a holding fixture in a Haas VF 4 SS with 12,000-rpm inline direct-drive spindle. This Haas machining center provides top quality surface finishes, thermal stability and very quiet operation. The new Kurt vise is an ideal workholding choice for this machine because of its many performance features. The vise has custom machined jaws for clamping the spindle shafts that vary in length from 14.32 inches up to 17.14 inches and are held to a 2.362 inch diameter. The dedicated steel jaws have been machined to hold specific part diameters so there is no need to change jaws between setups. (Photos Two and Three)
As for the machining process, both accuracy and speed are required while maintaining an overall high quality finish on all part surfaces. The spindle shafts are 86L20 steel with machined drive dogs at the shaft ends. Machine speeds and feeds on these spindles range from 1.0 inch end milling operations at 2700 rpm and 28.0 inches per minute to .375 finish end milling at 3056 rpm and 20.0 inches per minute. While the part-clamping requirement is very high, Mr. Linscheid reports that the new vise holds tolerances of +.005 - .000 without any variations to date.
New Model Kurt HDM690 Combines New Design Features With Time-Proven Operating Features
Haas Automation's new HDM690 has several new features over previous Kurt vise models. Foremost, the vise has a full 9-inch jaw opening so there's ample capacity for large spindle diameters and other large parts when needed. The vise's top-down bolting and tall body design is also new for reduced deflection. A narrower vise body also allows for more vises in the work envelop should more clamping stations be required.
The Kurt HDM690 vise also has high precision roller bearings and a specially hardened vise screw mechanism enhancing precision clamping and smooth operation. The design distributes up to 6,000 lbs of clamping force evenly and precisely across the full jaw surface.
Kurt's AngLock® spherical segment in the moveable jaw (time-proven and patented by Kurt) further reduces jaw lift. The pull-type body design stabilizes stress in the vise body resulting in accurate clamping for Haas cylindrical spindles as well as flat and irregularly shaped parts. (Illustration One)
Mr. Linscheid also said he liked the ruggedness of the Kurt HDM690 Double Acting vise models. Made of 80,000 PSI ductile iron, the vise bodies provide strength, rigidity and long-term accuracy while absorbing even slight machining vibration. Also, the vises have enclosed screws and clamping mechanisms so Illustration One Caption: Irregularly shaped parts such as the Hass spindles are clamped rigidly in this new Kurt HDM690 vise. Two design features ensure vise-clamping rigidity: the time-proven Anglock(TM) and the Pull-Type screw mechanism. No other vise or custom clamping fixture has these combined features.
chips don't foul up the hydraulic clamping mechanism - they clamp and unclamp quickly and accurately each cycle.
Easy setup features of this new vise include a stationary jaw that bolts down from the top. No need to remove from table to disassemble vise. Bolting the stationary from the top reduces the stress in the body and stays flatter after assembly. The vise has a movable jaw allowing for quick-change jaw carvability to hold the Haas cylindrical shaped spindles.
Mr. Linsheid reports that 200 to 400 spindles are machined each workweek using the Kurt HDM690 vise. The setup has been in operation successfully for about a year. A second cell incorporating another HDM690 vise setup is nearing completion and will be phased in as production orders increase. "We would not be capable of machining these spindle shafts in a robot cell without the Kurt HDM690's," Mr. Linsheid reported. "They were introduced at a good time and helped us increase productivity while lowering our costs.
For more information about Haas machining centers, call 1-800-331-6746. Website: www.haascnc.com Or write to Haas Automation, Inc., 2800 Sturgis Road, Oxnard, California 93030. Fax; 888-436-6565.
For more information about Kurt workholding, call for FREE brochure in USA and Canada, 1-877-226-7823. Outside USA and Canada, call 1-763-574-8309, or download it from the Kurt website: kurtworkholding.com. Or write to Kurt Manufacturing Company, Industrial Products Division, 9445 East River Road NW, Minneapolis, Minnesota 55433. In USA, Fax 1-877-226-7828. Outside USA, Fax 1-612-623-3902. Email: firstname.lastname@example.org