WINTER 2016

130 THE DISTRIBUTOR’S LINK
DEL WILLIAMS ELIMINATING DEFECTIVE FASTENERS WITH HIGHER RESOLUTION, 3D INSPECTION EQUIPMENT from page 52
Quality control is critical because
even small defects can cause big
problems in working with lightweight
materials, such as having to rework
engine blocks if male threaded
fasteners strip out of threaded
holes. If there’s an obstruction in
the SPR bore or the dimension is
wrong, the rivet may also fall out or
not sit flush, which can become a
potentially serious, visible quality
issue.
Higher Resolution, 3D
Inspection
To address these production and
quality issues, the increasing use of
lightweight materials is requiring
high-speed 100% fastener sorting as
well as more inspection capability
from fastener sorting machines.
“While in the past it was ok to look at a fastener’s
silhouette to see if it had a thread or gross thread
damage, now sorting machines need the ability to find
any defect,” says Nygaard. “Thread damage can be
anywhere, and if you’re not looking at it from 360
degrees, that burr will get you.”
Today laser and vision-based machines can provide
100% high-speed 3D fastener inspection. Some use 3D
information from multiple laser beams to detect defects
that may only be on one side of the part such as
damaged threads. Laser topography, in fact, can provide
a detailed 3D image of the part, detecting dents,
flatness, chips, and dimensional characteristics.
Other measuring machines use a series of advanced
vision systems to detect defects.
Such a multi-view
system can provide images from all around the part for
greater than 360° coverage, plus an ability to measure
all dimensions and find visual defects such as cracks,
scratches, porosity, and laminations.
Some advanced optional sensors can also provide an
axial view vision, so the camera can “see” the side of the
fastener head or flange to detect cracks or recess
defects. In addition, an internal viewer lens can expand
the view inside the part, providing complete detail of ID
threads for a full 360 degree view of the entire length, to
detect very small defects.
Eddy current sensors can also detect metallurgical
defects such as in plating or heat treatment, which can
help to prevent premature fastener rusting as well as
cosmetic defects. This can be vital in safety critical parts
such as a wheel bolt, which may be subject to constant
vibration or weather exposure.
While the most precise high resolution, fastener
inspection machines can measure with as little as 2
microns of total error, typical equipment can be several
orders of magnitude less precise.
“Eliminating defective parts is all about precision and
repeatability,” says Nygaard, whose company General
Inspection has over 40 patents or patent pending for
high-speed measuring and sorting fastener inspection
systems.
CONTINUED ON PAGE 166