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SPINDLE MANUFACTURER COORDINATES ENGINEERED TO PROVIDE TIMELY DELIVERY FOR HAZARDOUS APPLICATION
Grafton, WI, (7/30/99)
Lawrence Livermore National Laboratory (LLNL), Livermore, California, needed an accurate, low speed milling head for a new "remotely operated via PC" mini-mill application. Because Lawrence Livermore Laboratory was machining radioactive material, they needed a remotely operated mini-mill to be controlled from another room. LLNL decided on a M-7900 Series CNC Mini-mill by Servo Products, a leading supplier of mini-mills, since 1981, manufactured in the USA. The M-7900 Series CNC mini-mill featured a 10" x 5-1/4" x 3-1/2" work envelope. LLNL then needed a compatible motor to operate the spindle on the CNC mini-mill. They chose the DC brushless motor, model# FBLC-45-2 by SL-MTI, a respected supplier of high performance motion control products, that was capable of 110 volts input with analog output (0-10 DVC) for accurate speed control, and two discreet inputs for forward and reverse. The DC brushless motor used only three wires, making integration into LLNL's PC quite simple.
Both products were suitable to their needs. However, the Servo Products mini-mill was originally fitted with an air powered spindle. This spindle type could not work in the controlled environment that LLNL was working with because it was not capable of being controlled remotely via PC, and it was made for running at speeds as high as 30,000-40,000 rpms. The air powered spindle could not go slowly, 400-5000rpm, which is what the application required. For a highly accurate spindle that they could use with their Servo Products mini-mill and their SL-MTI brushless DC motor, they chose an 1875-X1M-ST cartridge spindle by SKF Precision Technologies, an ISO 9001 registered global supplier of high-precision machine components. The SKF Precision Technologies spindle fit the speed (400-5000 rpm) and accuracy (+/- 5%) specifications that the LLNL application required. High precision spindles are SKF Precision Technologies' area of expertise.
Now that LLNL had the required components with the appropriate specifications for their application, they needed them all to work together to make the application a success. The motor stator had to be mounted onto the input shaft end of the SKF Precision Technologies cartridge spindle, so no additional bearings were needed. But an endplate would be needed to which the modified spindle and DC brushless motor could be attached. SKF Precision Technologies was willing to work with both Servo Products and SL-MTI to make the necessary modifications so that the mini-mill, motor and spindle could work together. The SKF Precision Technologies engineers did the necessary drawings and produced the modified spindle in only four weeks. This was a remarkable turnaround. SKF Precision Technologies modified the end plate in order for the motor to be mounted directly to the spindle housing. SKF Precision Technologies also drilled holes in the spindle housing for fitment of the end plate. The DC brushless motor by SL-MTI could now fit the modified spindle. Because the spindle could now accept the brushless motor, a speed reducer or belt drive was not required, resulting in a lighter mini-mill. The reduced weight, in turn, produced less vibration, maintenance and noise, as well as a reduced cost. The application's maximum weight tolerance for the spindle and motor was 13 pounds. The modifications by SKF Precision Technologies and the addition of the brushless DC motor by SL-MTI weighed in at just over nine pounds.
The effort made by SKF Precision Technologies to integrate the three components from different manufacturers in a remarkable amount of time proved to make the application at Lawrence Livermore National Laboratory a success.
