There are
various methods to evaluate Zipper & Slider quality. The procedures
in various quality
standards
worldwide are more or less similar and are documented well under
ASTM, ISO, BIS, JIS,
DIN, ISI and
other well known International Standards.
Zipper &
Slider strengths are checked as a routine inspection, For this the
method laid out in
JIS-S3015 is
used. The same standard is used by the YKK also, the world's leading
Zipper manufacturer.
The basic
strength can be determined based on the following inspection
methods, from which all round
strength
appropriate for respective uses can be judged.
To determine
the Zipper Strength the Zipper Chain in closed position is clamped
in-between
specially designed Jaws of 25 mm width and pulled at a fixed speed
at 90 degree
angle to the chain interlocked direction.
The
resistance is measured in Kgf till failure.
TOP STOP
HOLDING STRENGTH
The lower
part of an interlocked Zipper is clamped and the Slider is pulled
right up to
the top stop. Holding strength is measured by pulling the Slider
against the
Top Stop in the Tensile Testing machine.