Miniature ball screws are compact screw-and-nut assemblies with small-diameter screws that use recirculating ball bearings in the nut to convert rotary motion into low-friction linear motion. Screw diameter is the nominal outside diameter of the threaded screw, while lead is the axial distance the nut travels during one complete screw revolution. Nut style determines mounting: cylindrical nuts install inside a machine-specific housing, flanged nuts bolt directly to a plate or carriage, and externally threaded cylindrical nuts screw into an internally threaded machine component. Nut fit controls play between the screw and nut; standard fits allow limited backlash, while transitional fits reduce play and may add slight preload.
PBC Linear BSR Miniature Ball Screws are designed and manufactured in the USA in six standard screw-diameter-and-lead combinations: 6mm × 1mm, 6mm × 2mm, 8mm × 1mm, 8mm × 2mm, 8mm × 2.5mm, and 10mm × 2mm. Cylindrical, flanged, and externally threaded cylindrical nut styles are available. Standard products use Grade 10 precision-rolled screws, while Grade 5 and Grade 7 accuracy are available through the configurator. Grade numbers define permitted lead variation over the screw length, with lower numbers indicating tighter lead accuracy. Assemblies support static axial loads up to 2.144kN (482lb) and use an integrated multi-liner ball-return system. Cylindrical and flanged nuts include polymer wipers at both ends to help block debris and retain lubrication, while externally threaded nuts omit wipers for compact mounting.
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Contact an Application Engineer for ordering a specific grade at application.engineering@pbclinear.com.
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