Page 82 - ENGINEERING REVIEW APRIL 2022 DIGITAL MAGAZINE

TECH INNOVATION
# SCREW TECHNOLOGY

Evolution of the trapezoidal thread: New

igus standard achieves 82 percent efficiency

Harmonised lead screws & lubrication-free lead screw nuts extend service life by 30 percent

Even tried and tested structures have potential for improvement. One example is the classic trapezoidal thread,
which igus has refined. Thanks to a special geometric interaction between the lead screw nut, which requires no
lubrication or maintenance, and the metal lead screw, dryspin technology promises a long service life, improved
efficiencies, low wear and less movement noise. Now dryspin lead screw technology is available in eight new
installation sizes.
rapezoidal threads have been vibration, which can take the form of
mechanical engineering classics for rattling or squeaking. Hendricks remarks:
Tdecades. The machine elements “The rounded tooth flanks allow the
convert rotary motion into linear motion - lead screws to move without vibration
in such applications as window and door and almost silently. The lead screw
drives, format adjustments in production manufacturing tolerance is tighter than
plants and laboratory technology. that specified in DIN 103 7e, ensuring
However, almost every classic has more precise operating behaviour and
potential for improvement. “We have allowing for much higher speeds in the
tackled a market standard, and are able application.”
to say that we can do even better”, says
Thorben Hendricks, Head of the dryspin Eight installation sizes added to
Lead Screw Drive Business Unit at igus. the dryspin lead screw technology
The motion plastics specialist relies on portfolio
optimised interaction between the metal igus began establishing its own lead
lead screw and the plastic lead screw nut The evolution of the trapezoidal thread: screw technology on the market in
geometries. low wear and noise, but instead a long 2013, initially as an alternative to high
service life and high efficiency. That is helix threads. Now there are eight new
30 percent longer service life, 82 what igus promises with its dryspin installation sizes - harmonised lead
percent efficiency technology (Source: igus GmbH) screws and lead screw nuts, including
At igus, the nut’s thread flanks are dimensions with low pitches that enable
larger than those of classic trapezoidal flank angles of the lead screw nut and quick one-to-one replacement of installed
threads, as is the width of the lead screw. lead screw. This gives us above-average trapezoidal threads. The new lead screws
This is a small change, but it has major efficiency - up to 82 percent at high are available with pitches of 6.35x6.35
consequences: enlarging the thread flank pitches.” RH, 8x40 RH, 10x3 LH, 12x25 LH, 14x4
results in more high-performance plastic RH, 16x5 RH, 18x4 RH and 20x10 RH.
being used for power transmission. This Lead screws work almost noiselessly The lead screws are made of stainless
means more material that is tribologically and with low vibration steel or aluminium; the lead screw nut
optimised, i.e. regarding friction and wear. However, the new dryspin thread material can be selected from seven
“The asymmetry has enabled us to extend technology is not only durable and high-performance plastics and several
the service life so that it is about 30 efficient, but also quieter than many geometries - from a cylindrical design
percent longer than that of symmetrical conventional trapezoidal threads. This with flange or spanner flats to a version
trapezoidal threads”, Hendricks says. is due to the fact that the tooth flanks with spring pre-load.
Optimising the flank angle also increases are not angular, but rounded, reducing
the amount of energy supplied that can the contact area between lead screw For more information,
actually be used. We have flattened the nut and lead screw. This leads to less Website : www.igus.com

80 | APRIL 2022