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dryspin  lead screw technology | General information                                                                     dryspin  lead screw technology | General information
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        Radial loads                                          Lead screw drive inspection                                        the lead screw nut in the axial direction without movement
        dryspin  lead screw nuts are designed to absorb axial   dryspin  trapezoidal lead screw drives are manufactured          of the lead screw. Lead screw units require a minimum
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        forces. By using tribologically optimised iglidur  sliding   in accordance with DIN 103. Inspection is performed with    clearance to maintain their function. If the axial clearance
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        materials, dryspin  lead screw drives can also absorb   standard thread plug gauges after production. The DIN 103        is too small, the torque required to move the lead screw
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        slight radial forces in contrast to ball screws. However,   standard is converted to the corresponding size for any      nut will also increase. Application-specific parameters must
        uncontrolled radial forces lead to uneven wear and thus   thread sizes that are not shown in the standard table.         be observed in addition to the lead screw drive clearance
        to a reduced service life. Any radial forces occurring in the   The hygroscopic and thermal properties of the material   caused by manufacturing tolerances. In addition to thermal
        application should be absorbed by additional linear guides.  must be taken into account during selection. Dimensional    and hygroscopic environmental influences, the minimum
                                                              changes can occur as a result of moisture and/or thermal           clearance to be considered in the application must also
        Temperature                                           exposure at the point of use. For these reasons, general           take into account the friction heat generated by the
        dryspin  lead screw nuts, made from the maintenance-  DIN compatibility cannot be guaranteed.                            application. This plays a decisive role in connection with the   8 anti-backlash lead screw nuts (AB) -
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        free iglidur  materials, are generally suitable for use in                                                               expansion behaviour of the polymer material used. As the   yellow = axial clearance, orange = pre-load
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        the temperature range from -20°C to +90°C (+150°C,    Noise                                                              axial clearance in the system can change with temperature
        depending on the material). It should be noted, however,   Noises can generally occur with lead screw drives. This       fluctuations. For lubrication-free lead screw drives, the
        that in addition to a change in the clearance due to   applies in particular to long lead screws or long travels or to   basic clearance is approx. from 30µ to 50µ. An effective   Anti-backlash lead screw nuts (AB)
        temperature expansion, there is also a change in the   lead screws that are only supported on one side. Such thread      measure for reducing unwanted clearance, in addition to   Backlash is created on the lead screw drive by the axial
        maximum permissible load. From a temperature of <0 °C,   systems can lead to self-generated vibrations. Lead screw       the correct material choice, is a pretensioning mechanism.    clearance. By adding a small radial pre-load, vibrations
        due to the different temperature expansion coefficients   nuts made from the tribologically optimised iglidur  materials   The use of lead screw drives is therefore not recommended   are significantly reduced. Though a significant backlash
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        between metal and plastic, there can be an increase in the   tend to be significantly quieter than conventional plastics or   for precision drives without conducting practical tests. In   reduction cannot be achieved.
        required drive torque, which results in sluggishness. In this   metallic materials such as bronze or brass due to their good   addition to the solutions from our standard product range,   u Page 466
        case, the lead screw nuts should be manufactured with a   sliding properties when operating dry. In general, one can say   our technical support team will be pleased to discuss other
        slight allowance or recut.                            that tougher materials such as iglidur  R or E7 produce the        options.
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        When the application is exposed to temperature and load   least amount of noise and are therefore particularly suitable
        extremes, we recommend testing the suitability of the lead   for highly dynamic applications. Another option for noise   Levels of efficiency
        screw nuts in this specific case by a practical test. In order   reduction are pre-loaded lead screw nut types. If is noise   Efficiency is the ratio between the output and input power
        to provide for the use in all temperature ranges, we have   in your lead screw drive, please speak to our experts and    rating. In the calculation, the efficiency is abbreviated with
        lead screw nuts available in various clearance classes.  we will find a suitable material pairing for you.               a small eta (η). dryspin  lead screw nuts are characterised
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                                                                                                                                 by a low coefficient of friction, resulting in high efficiencies.
        Wet environments                                                                                                         Single start trapezoidal lead screw nuts achieve efficiencies
        Trapezoidal lead screw nuts made from iglidur   J or                                                                     between 14 and 48% in dry operation. High helix lead
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        iglidur  A180 must be used for applications in humid                                                                     screw nuts achieve efficiencies up to 82% in dry operation.
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        environments, especially for wet applications. These                                                                     Even though dryspin  lead screw nuts were developed for
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        material are characterised by very low moisture absorption.                                                              completely dry operation, lubrication can help to additionally   9 lead screw nuts with radial pre-load (low clearance,
                                                                                                                                 increase efficiency.
        Dirt                                                                                                                                                                          LC) - yellow = axial clearance, orange = pre-load
        With the use of the maintenance-free iglidur  materials                                                                  Self-locking
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        for lead screw nut production, dryspin  lead screw drives                                                                Single start trapezoidal screw drives are self-locking in most
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        feature completely dry operation. Due to the deliberate                                                                  cases. This means that the flank angle and the sliding friction   Lead screw nuts with radial pre-load
        avoidance of lubricants, the adhesion of soft particles   Yellow markings show the axial clearance of a                  prevent movement of the nut or the lead screw without the   (low clearance, LC)
        such as dust and fibres is reduced. When compared to   standard lead screw nut                                           application of outside forces. As soon as the static friction   LC lead screw nuts reduce backlash caused by axial
        conventional, lubricated materials, it is common to see                                                                  is exceeded, the components are no longer self-locking.   clearance in a lead screw drive. The rear part of a slotted
        significant improvements in the service life in contaminated   Clearance                                                 Multi start trapezoidal screw systems have a "residual self-  lead screw nut is radially pre-loaded around the lead screw
        environments. However, in environments with significant   Axial clearance can be used to describe the lost motion,       locking" feature; high helix screw drives have no self-locking   by means of a strong, radial pretension using two elastomer
        contamination and hard particles, such as metal swarf or   the "dead travel", on the lead screw as a result of the gap   feature. Since the self-locking depends both on the pitch   rings (O-rings). The tooth flanks of the nuts are pressed far
        granite dust, the lead screw should be covered.       between the lead screw and the lead screw nut. The term            angle and on the coefficient of friction of the sliding pair, a   into the lead screw profile so that there is a pretension and
                                                              clearance is also often associated with it, but the correct        loss of self-locking can occur with very low coefficients of   thus a reduction in the axial clearance.
                                                              technical term is axial clearance. It is thus the movement of      friction even with single start trapezoidal threads.   u Page 460
                                                                                                                   ASEAN 09/2023  ASEAN 09/2023




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