Visual method of inspecting the yarn uniformity requires wrapping the yarn on a board and comparing it to a standard
sample. In addition to yarn regularity, periodic defects such as moiré effect can also be determined when the yarn is
wrapped on a taper board.
Lawson-Hemphill Conical Table uses Transverse Mechanism to wrap the yarn around a Taper Board. This mechanism
ensures yarn wraps are equally spaced on the board as per yarn count. ASTM D 2255 provides a reference table for
proper spacing. The standard version of the Taper Board instrument is equipped with one Yarn Carrier. Dual Yarn
Carriers for comparing two yarns side by side and Double Step version to double space between each wrap are also
available as special versions for heavier yarns or fancy yarns.
When the test starts, the Yarn Carrier is placed at the narrowest part of the taper board. As the wrapping continues,
the yarn carrier will continue to bring the yarn towards the wider parts of taper board. The winding will stop
automatically when the carrier reaches the widest part of the board. The taper board can then be removed to inspect
the yarn. During the winding, the yarn is under tension. The winding speed is manually adjustable and the machine
can be stopped at any
