We incorporated high-end, lead screw motors along with machined end journals
Fixed, flat, keyways, and threaded journals can be machined for multiple lead screw uses. PBC Linear offers customers a wide variety of optimized nut geometries, along with the ability to quickly customize screw journals. The final addition to the lead screw assembly is the drive system. The lead screw is first matched to a hollow shaft motor and then precision mounted. The motor’s hollow shaft concentricity serves to minimize runout to values less than 0.003 inches (75 μm). In the final step, the I.D. is laser-welded to the motor, creating a uniquely harmonious unit. Closer inspection of the drive system reveals important features and options, including:
- Larger bearings that increase thrust capacity and add longer life.
- Preloads on bearings that remove axial play and reduce system backlash.
- Optional smart motors.
- Connection via EtherNet/IP, EtherCAT® P, or Modbus®.
We built in a more comprehensive metrology at each stage of lead screw production
PBC Linear implements microscopic inspections of the surface finish at each level of the manufacturing and coating process. At the threadform stage, our acute inspections validate major and minor profile diameters, with additional emphasis on pitch, flank angle, etc. The resulting maximum screw runout is less than 0.001 inches (24.4 μm).
When comparing the PBC linear lead screw to industry competitors, we find our lead accuracy is 0.003 inches/feet (76 μm/300 mm), which is three times better than the level of typical industry specifications. Further comparisons reveal that PBC Linear inspects one hundred percent of its screw length, which on the finest leads is up to twenty-thousand points over seventy-two inches. In contrast, our competitors only take their data points every six inches over the same length of screw.
During the automated straightening process of the lead screw, PBC Linear consistently yields the highest straightness tolerances available. At the finish coating stage, each screw is thoroughly inspected with a digital microscope to ensure there is no flaking or pitting on the surface coating. This smoother finish, coupled with a precise and uniform length, makes for a much longer product life.
Along with lead screws, our intensive metrology standards are applied to anti-backlash nuts and journaled ends. Customers can rely on PBC Linear for reliable products that have been inspected to ensure backlash tolerances meet precise specifications. These high standards are applied to screw journals as well, allowing then to be ground to less than 0.0005 inches (12um).
Overall, PBC Linear dedicates two separate test labs that are focused on establishing high performance characteristics within their product line. One lab is used for load and life, where assemblies are required to run in excess of 2,500 miles without failure. The other test lab is sound-proofed, which allows our technicians to effectively analyze product noise levels. At the end of the day, it is plain to see that PBC Linear has achieved its goal of creating a better lead screw assembly.