Page 371 - IGUS Linear

dryspin lead screw technology | General information dryspin lead screw technology | General information
®
®

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
®
®
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
®
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
®
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) -
®
free iglidur materials, are generally suitable for use in expansion behaviour of the polymer material used. As the yellow = axial clearance, orange = pre-load
®
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
®
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.
®
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
®
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
®
iglidur A180 must be used for applications in humid screw nuts achieve efficiencies up to 82% in dry operation.
®
environments, especially for wet applications. These Even though dryspin lead screw nuts were developed for
®
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
®
for lead screw nut production, dryspin lead screw drives Single start trapezoidal screw drives are self-locking in most
®
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

368 Online tools and more information u www.igus-asean.com/dryspin 3D CAD files, prices and delivery time online u www.igus-asean.com/dryspin 369