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Machine tool slideways made of
metallic material (typi-cally, cast Iron, Steel or Bronze) show an
undesirable tendency to seize under high loads and speed as well as on areas
of continuation caused by grinding dust, chips or under dry running
conditions. Further, such slide partners shows stick slip motion caused by
different functional value associated with static and sliding conditions.
This motion is marked by periodic sticking following by jerking motion.
Preload feed members or backlash in the feed control may increase this
effect.
Roller bearing elements are
being used to reduce deformation of this feed control members due to static
preload. However, because these have only a point or line contact, they can
show unfavourable vibration damping behaviour. A slip coat material, Diamant
Moglice, from Diamant Metallplastic GmbH, Germany, has shown good results
because its coefficient of friction during sliding is only slightly
different to its coefficient of friction at creep speed. The coating
consists of a two-component epoxy resin formulation which can be applied by
spatula or by an injection replica moulding process which does not require
any further machining or scraping since the counter moulding part is just
replica in finish and profile. Recently, American robot manufacturers have
coated all bearing surfaces in robot arms with the aim to eliminate roller
bearings. However, the coating can also be used on parts, which have a non
sliding relative motion. For example, a hydrostatic, guide bush worm/tooth
rack combination demands precise alignment of worn centre to tooth rack to
achieve an optimum hydrostatic gap.
In the same manner, there is
another material, Diamant DWH. The application method is same as above and
is being used for correction of machining tolerance as well as aligning of
various components of machine tools. Other application examples are
alignment of bushing without mechanical jig boring, pallet locating pins,
hardened slideways in place, machine parts, head stock, steady rest, bed
joint, bed on base, etc. Many other products are also available for building
up and repairing worn out surfaces (cold welding) such as bearing shaft and
spindle, for filling score marks, shrink holes and porous castings.
(Diamant Triumph Metallplastic
Pvt Ltd, Bangalore. Tel: 080-25727678, 25720643. Fax: 91-80-25720643.
E-mail: dtmp@dataone.in)
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