Precision Leadscrews and Nut Assemblies

Reliance’s lead screw and nut assemblies provide a flexible, integrated solution for linear motion. Available in a wide choice of lead screw sizes and nut styles, with options for custom designed nuts and lead screw end modifications, the range offers the flexibility to address a wide variety of requirements.Lead screws are provided with leads from 0.3 mm to 92 mm, screw diameters from 3 mm to 19 mm and thread lengths of up to 4 metres, making them an effective solution, even for high linear speed applications. They are available in a range of materials and coatings, with a choice of cut or standard interfacing ends, or with the option of custom machined ends. The screw thread form has been specifically designed for long life and quiet operation. It is manufactured using a rolled process, a highly consistent method of production resulting in a cost-effective, quality product. The lead screw and nut assemblies have been designed specifically for motion control applications, rather than using adaptations of general purpose screws and nuts. There are 11 different lead screw nut styles, with a choice of mounts and also options for custom-designed nuts. The lead screw nuts are made from moulded plastic, which enables custom nuts to be produced with features of the drive system, such as bushings, carriages, pulleys and gears, integrated within the nut. This type of custom, multi-functional nut can offer a significant reduction in part count, reducing cost and assembly time in the overall mechanism. The polyacetal nuts have a lubricating additive to provide longer life which, when combined with low friction leadscrew coatings, can extend the life of a standard leadscrew assembly by up to 300%. The assemblies are self-lubricating, making them ideally suited to medical and laboratory applications.With lead accuracies up to 0.0001 mm/mm and positional bi-directional repeatability within 1.5 micron (0.0015 mm) on anti-backlash designs, the leadscrew and nut assemblies are ideal for applications requiring precise, efficient linear motion.Lead screw materialsLead screws are rolled from a premium grade, corrosion resistant and non-magnetic 303 stainless steel. Other materials are available including 316 and 400 series stainless steel, precipitation hardened steels, aluminium and titanium. These materials are ideally suited for industries such as medical, vacuum, cleanroom, food and human contact, salt spray and cryogenics.Lead screw coatingsStandard lead screw nuts are manufactured from self-lubricating plastics. We also offer soft TFE and hard BFE low friction coatings for the lead screw; lubrication to the screw/nut interface occurs by the nut picking up TFE particles from the coating as well as from migration of the internal lubricant from within the plastic nut. We also supply leadscrews with specialist nickel/TFE coatings and offer a choice of coatings used in medium vacuum applications (up to 10-5). Alternatively a BFE coating can be provided. This is a special proprietary hard coating which shares many of the benefits of TFE coating but offers exceptional durability in more aggressive environments and where reduced friction and a permanent coating is desired.Although care should be taken to ensure that chips and voids do not occur in the coating, small voids have been shown to have little effect on the system performance. The lubricant, although solid, has some of the “spreading” ability of fluid lubricants. When machining bearing ends, soft fixtures are recommended to protect the coating.TFE coated screws provide the maximum level of self-lubrication and should not be additionally lubricated or used in environments where oils or other lubricant contamination is possible.Coatings, available for only a small additional cost, give the best results on wear life, coefficient of friction and torque to drive the leadscrew assembly. To select a coating add -TFE or -BFE to the part number shown.Leadscrew endsLeadscrews are provided with the options of cut ends or a range of standard end modifications suitable for interfacing with ball bearings, circlips, couplings, pulleys and gears. Alternatively custom end modifications can be supported.Reliance can provide tremendous value by producing a mult-functional nut. Using custom moulds and special machining, nuts can also include guide bushings, carriages, timing pulleys, gears, syringe components, sensor mounts and flags, encoder features, clamps and many other complementary elements.

For more information on Precision Leadscrews and Nut Assemblies talk to Reliance Precision Limited