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Screw Backdriving Efficiency
Posted August 22, 2019 - Updated Dec 12, 2019
Efficiency and Backdriving The mechanical efficiency of screw drive systems is often confusing. This is because unlike most power transmission components, V-belts, sheaves, timing belts, chain drives, and gear systems (with the notable exception of worm gear systems), screw drive systems actually exhibit two efficiencies – one in the drive direction (torque to thrust conversion) […]
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Application Engineering: Speed
Posted August 22, 2019 - Updated Dec 3, 2019
Speed Basics Linear speed is dictated by the functional requirements of the application. Rotational speed is a function of the linear speed and the lead of the screw. Rotational speed (rpm) is equal to the linear speed (in./minute) divided by the lead of the screw (in./rev.). Leads are listed in the Screw/Nut Engineering Data for […]
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Screw Actions
Posted August 22, 2019 - Updated Dec 3, 2019
The primary concern in any screw and nut system is the amount of load to be moved. The load must be determined by the designer before the proper type and size of screw can be selected. If the load is to be moved vertically, the nut load is equal to the weight to be moved […]
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Ball Screw Wear Life
Posted August 22, 2019 - Updated Dec 3, 2019
Wear life of Ball Screws The wear life of Ball Screws is much more predictable than Power Screws due to the large body of research and testing that has been conducted on ball bearings and bearing balls. Assuming that a Ball Screw is a ball bearing arranged with helical inner and outer races, the listed […]
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Ball Screw – Speed
Posted August 22, 2019 - Updated Dec 3, 2019
Speed for Ball Screws Ball velocity in a Ball Screw should not exceed 3,000 rpm x in. (rotational speed (rpm) times the nominal diameter (in.)). For example, a 3/4 x .200 size Ball Screw should be limited to 4,000 rpm (3,000/.750 = 4,000 rpm). For applications requiring speeds beyond 3,000 rpm x in., use a […]
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Power Screw – Wear Life
Posted August 22, 2019 - Updated Dec 4, 2019
Wear Life of Power Screws The wear life of power screws is a function of: Load Speed Lubrication Contamination Heat and other factors. The operating loads listed in the Screw/Nut Engineering section for each screw series provide acceptable wear life for most applications. Wear in a power screw is generally in proportion to usage. Each […]
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Ball Screws
Posted August 22, 2019 - Updated Dec 3, 2019
Ball Screw Basics Ball Screws, first invented in the late 1800s, did not come into widespread use until the 1940s when they were adapted for use in the automotive steering gear. Since that time they have been used in a variety of industrial and commercial applications due to their high efficiency and predictable service life […]
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Speed for Power Screws
Posted August 22, 2019 - Updated Dec 4, 2019
Power Screws, Speed and Efficiency Along with efficiency, speed for power screws is one of the most important considerations when selecting a product. Acme screws are most commonly used at 100 rpm or less, with some applications running in the 300 rpm range. Because of their relatively low efficiency, when faster traverse rates are needed, […]
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Power Screws Basics & Materials
Posted August 22, 2019 - Updated Dec 3, 2019
Power Screws Basics Power screws cover a wide variety of screw series and include Acmes, Hi-leads®, Torqsplines® and other special series (not offered in this catalog but produced for OEM customers) such as Stub Acme, Trapezoidal (“metric Acme”) and Buttress. Regardless of the thread series, an externally threaded screw mates with an internally threaded nut […]
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Types of Screws
Posted August 22, 2019 - Updated Dec 12, 2019
There are two general types of screws used to create motion and power: Power Screws and Ball Screws. Power Screws Power screws are the simplest of these as they have only two main elements, the screw, and the nut. Considerations for application and selection of power screws include: Power screw basics and materials Speed for […]