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Wear Equations
Posted August 22, 2019 - Updated Dec 4, 2019
Wear Equations As discussed earlier, estimating the service life of Power Screw systems is a very complex task and inexact at best. The only reliable predictor is actual testing. Variations in service life are widely scattered and multiples of two to one or three to one in life test performance are not uncommon. The field […]
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Monitoring Wear
Posted August 22, 2019 - Updated Dec 4, 2019
Wear Life Testing Methods As mentioned before the best method of assessing the performance and life of Power Screws and nuts is actual field testing. This may present difficulties because of time constraints so accelerated lab testing is often conducted instead. When monitoring wear, all lab testing should monitor drive torque and nut temperature along […]
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Screw and Nut Material Selection
Posted August 22, 2019 - Updated Dec 4, 2019
Screw and Nut Material Selection To reduce the costs of wear in Power Screw systems, we recommend designs where nuts are made of softer material and screws of a harder material. This ensures that the nuts will wear and the screw will remain relatively wear-free, which is desirable because replacement nuts are usually much less […]
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Wear Mechanism
Posted August 22, 2019 - Updated Dec 4, 2019
Wear Mechanism The study of wear is a field called tribology. There is much research on the subject, but little definitive work that can help determine the wear rate of two surfaces in any specific application. The wear mechanism itself is simple to understand. With reference to Figure 38, two rubbing surfaces contact only at […]
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Screw Wear Life
Posted August 22, 2019 - Updated Dec 4, 2019
What is a Screw Wear Life The wear life of Power Screw and nut drive systems are difficult to predict theoretically. The number of variables involved in such a prediction is large; load, speed, screw material, nut material, surface finishes, lubrication, duty cycle, operating temperature, and environmental factors such as the presence of abrasive contaminants, […]
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How to Straighten Screws
Posted August 22, 2019 - Updated Dec 4, 2019
How to Straighten Screws Basics For users who elect to straighten their own screws or who need to straighten a bent screw, we offer the following guide. Straightening methods which are suitable for plain (non-threaded) bars such as roll straighteners or crossed axis roll straighteners do a poor job on lead screws and should not […]
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Preserving Straightness in Screws
Posted August 22, 2019 - Updated Dec 4, 2019
Preserving Straightness Screw shaft straightness is a perishable feature. It is very easy to bend shafts during routine handling, machine loading, during machining and during in-plant transportation. Even inside a wooden crate shaft can be easily bent if precautions are not observed. When transporting screws, it is best if the screws are supported in two […]
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Methods of Achieving Straightness
Posted August 22, 2019 - Updated Dec 12, 2019
Methods of Achieving Straightness Unless special straightening is requested by the customer, Roton will ship screws in “as rolled” straightness condition. For most applications, this level of straightness is sufficient and cost-effective. But some applications have more demanding straightness requirements. Users with applications requiring screw shafts to be straightened beyond “as rolled” condition should specify […]
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Screw Shaft Straightness & Defects
Posted August 22, 2019 - Updated Dec 4, 2019
Introduction to Screw Straightness & Defects A lack of screw straightness can become a critical factor in any application. Bent lead screws can cause noise, premature wear and failure, high drive torque, and excessive heat. But straightness requirements vary widely from application to application, and straightness is an expensive and perishable product feature. For these […]
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End Fixity
Posted August 22, 2019 - Updated Dec 3, 2019
What is End Fixity? Screw end fixity is the engineering term for screw end support. Fixity is an important element in screw and nut drive systems. The rigidity of the screw end support determines the screw drive system’s resistance to column buckling and limit of the speed of rotation to avoid natural frequency vibration. (See […]