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FIELD
REPORTS
Indicators, calipers clinch fastener quality
The Sylvac Ultra Digital Mark V indicator measures the height of a typical cold-drawn
steel fastener.
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The Sylvac Ultra Cal Mark III caliper measures fastener widths.
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When fastener company MacLean-Fogg, Mundelein, IL,
revamped and converted its manufacturing operation to a cell production system three years
ago, it moved from completely analog inspection instruments to electronic digital devices.
To assure high quality in its broad line of fasteners, the company searched for metrology
products that would tie its line of gages directly to its statistical process control
(SPC) data software.
Among the more than 200 gages MacLean-Fogg uses in its quality assurance operations,
highly accurate calipers and indicators are key, says Quality Assurance Manager Layne
Urquhart. "We produce a diversity of fasteners in two nearby plants in a totally SPC
system. From raw materials to final production of our finished fasteners, we need a high
level of accuracy from several types of instruments."
Fresh start
Founded in 1925, MacLean-Fogg's product line now comprises suspension components,
locking fasteners, fastener systems, axle and shaft components, engineered components, and
specialty inset-molded components.
MacLean-Fogg purchased the Fowler/Sylvac Ultra Digital Mark V indicators and Ultra-Cal
III calipers. "Sylvac was the only indicator and caliper having one cable
satisfactory for all the different Sylvac gages," says Urquhart. "What we needed
was new, highly accurate and fast-acting gages. We didn't need more cables."
As for the indicators, the Sylvac gage includes more than one reference mode which
allows the company to measure many parameters with one indicator. He adds that the two
plants also required gage uniformity and reliability in addition to robustness and high
accuracy. The Ultra-Cal III Sylvac calipers have an accuracy of 0.001´´ and resolution
of 0.0005´´.
Another Fowler Swiss-made instrument purchased by the upgraded plants is the Trimos
mini-horizontal height gage which MacLean-Fogg uses to measure parts and calibrate its
other instruments.
The company needed to measure some 20 characteristics or parameters with one
indicator--width across flats, overall thickness (or height), minor diameters (hole size),
thread pitch and countersink (chamfer). Previously, MacLean-Fogg used analog indicators,
which were subject to human error.
Process
The automated process of fastener manufacturing involves three inspection points. The
first inspection is made after the coiled-rod raw material goes through a cold head
forming operation and the cutting oil is removed for recycling. The product then is
distributed to the tapping machines, after which the processing oil is removed and a
second inspection is provided. The fasteners then drop to another conveyor and another
spinner for final finishing and a final inspection. With threads from 5 to 10 mm, the
fasteners are primarily shipped to domestic and overseas automobile and other
manufacturers.
The drive for higher quality--which prompted the switch to the totally SPC cell system
in 1995--stemmed from both customer demands and the Fastener Quality Act of 1997.
"By revamping both the Richmond and Mundelein plants and obtaining our QS-9000
certification in early 1997, many new markets are open to us," Urquhart says.
Fred V. Fowler Company, Inc., 66 Rowe St., Newton, MA 02166. Phone: (617)
332-7004. Fax: (617) 332-4137. Circle 191
[qm/incl/99qm.htm]
Please Note:
Some pictures or diagrams are only
available through the printed media.
This article was originally published in the Mar/Apr 1999 issue of Quality
in Manufacturing. |