is a Progressive tool we designed. It is intended to run at
a speed of 80 spm to progressively punch 60 holes of 0.5 mm
diameter into a tin-coated area. The product is extremely
sensitive to oil and dust. Therefore, no lubricant was utilised
during the entire punching process.
will be punching into a 0.1mm thick polymer which is coated
with a 0.05 mm thick copper strip. The area to be cut was
coated with Tin of 0.1-0.15 mm thick.
encountered: Stripper jams after every 20-30,000 strokes.
Galling Effect occured on the tips of each punch.
suspected that thoes punches surface were too rough, causing
temperature to increase with each punch. Hence, the tin melted
and was welded on the punchs surface. Overall, this
led to an increased in friction between the punches and stripper
polished all small punches to a surface finish of Ra 0.05.
In addition, we coated them with TiCN to reduce friction.
Unfortunately, there was no significant improvement and the
stripper still jammed after ~40,000 strokes of continuous
all punches and coated them with TiCN, reduced the stripper
guiding land from 1.0 mm to 0.5mm to further reduce contact
After this modification, no stoppages were observed after
5 days of continue production.
guide reduced from 1.0mm to 0.5mm
When cutting soft materials with low melting points, Galling
Effect occurs as soft material will build up on the punches
surface. This increases the stripping force and might cause
the punch to break off. Surface of cutting elements such as
punches, have to be as smooth as possible to reduce friction
between material to be cut and cutting elements. Polishing
it to Ra 0.05 and coating with TiCN is advisible.
unnecessary guiding, thus reducing surface contact, to avoid
excessive friction is the key.
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