20, 1998 Design News
Assembly options grow
You've just designed a great
new product, but need the perfect fastening solution
to keep it all together. Lucky for you manufacturers
of fastening and assembly products are focused on tackling
your most challenging problems. †† Here's
a sampling of some of their solutions
Deana Colucci, Associate Editor
Fastener improves low-ductile performance
PROBLEM: In recent years, the use of die-cast
magnesium in automotive, computer, and other applications
has increased significantly. Unfortunately, fastening
this material can be a challenge because of its low-ductile
nature. For example, standard thread-forming fasteners,
with a 60-degree flank angle, create excess debris.
They can easily exceed the ductility limits of the material,
causing damage to the formed threads.
SOLUTION: The patented Mag-FormTM
thread-forming fastener features a lobular configuration,
wide-spaced thread design, and broad flank angle. These
features help eliminate costly and time-consuming tapping
operations, and form strong mating threads in low-ductile
materials, says manufacturer Camcar Textron.
As the fastener is driven,
the high-degree flank angle compresses the mating
material, rather than roll-forming it. This action creates
strong mating threads while minimizing debris generation
and decreasing the potential for fracture of the application
material. And, the formed mating threads allow multiple
removals and reinsertions of the fastener.
APPLICATIONS: Mag-Form fasteners are suited
for use in a variety of automotive applications, including
steering wheels, instrument panels, and powertrain components.
Weld system compensates for changes
PROBLEM: Fluctuations in welding conditions,
surface contamination, and changes in mechanical timing
can interfere with effective welding.
SOLUTION: The self-diagnostic Stud Welding System
(SWS) monitors and compensates for such changes. It
comprises a TMP Welder Control, a Stud Feeder, and a
The TMP Weld Control switch-mode power supply provides
timing and control functions for the system. A microprocessor
performs thousands of finite electronic analyses, adjusting
weld current, arc voltage, welding time, and stud-plunge
timing to compensate for varying surface conditions
such as oil, grease, and blemishes. Increases or decreases
can be as much as 25% of weld parameter.
Wide ranges of weld parameter adjustments allow precise
weld schedule control and tolerance monitoring with
fault alert and out-of-parameter signaling capabilities.
SWS software transmits fault signals to the weld controller
after three consecutive parameter-tolerance violations
at the same weld location. It then automatically replaces
the welding tool without interrupting production.
APPLICATIONS: The Stud Welding System is suited
for heavy transportation, machinery, construction, and
furniture applications; as well as the manufacture of
electrical, electronic, and recreation equipment.
Threaded fastener delivers strong right angle in thin
PROBLEM: Thin panels make it difficult to create
a strong right-angle attachment in sheet-metal applications.
Cut-outs often made in panels to form right angles can
reduce EMI/RFI shielding. In addition, bent tabs at
the edges or in the middle of sheets, bent flanges,
right-angle brackets, and tack welds can reduce design
SOLUTION: The PEMr steel R'ANGLETM
threaded self-clinching fastener provides a strong right-angle
attachment point in both steel and aluminum sheets as
thin as 0.040 inch (1 mm). These Type RASTM
fasteners are pressed into a rectangular punched hole
in the sheet, mounting securely and permanently with
the reverse side of the panel remaining flush. Once
the fastener is mounted, the threads on the fastener
enable a second panel to be attached to the first using
a standard machine screw. The result is an extremely
close-tolerance, tight fit that resists vibration and
has excellent strip-out characteristics, says maker
Steel R'ANGLE fasteners
are an alternative to bent tabs at the edge or in the
middle of sheets, bent flanges, right-angle brackets,
tack welds, and loose hardware. Zinc-plated for corrosion
resistance, they can eliminate welding, eliminate tab
cutouts for better EMI/RFI shielding, and decrease both
the amount of loose hardware and the number of assembly
steps. The screws can be removed and reinstalled repeatedly
without compromising the fastener's holding power.
APPLICATIONS: Steel R'ANGLE fasteners can be
used for component assembly in the electronic, automotive,
aerospace, and telecommunications industries.
Large-head stud delivers speed and security
PROBLEM: Noise shields are often required to
meet sound reduction standards. Unfortunately, secure
panel attachment can mean more hardware and special
panel preparation, increasing assembly time and costs.
SOLUTION: Large Head Rapier Studs enable noise
attenuation panels to be securely attached with a lightweight,
low-cost fixing, yet be easily and quickly removed.
The enlarged head diameter provides a simple and secure
quarter-turn fixing method that eliminates the need
for supports, washers, or any intermediate elements.
Slip-on Long Reach receptacles complement the studs,
giving support in ranges from 0.9 to 5.7 mm with maximum
torque values of 22.15 in-lbs and 31 in-lbs across three
APPLICATIONS: Quarter-turn Large Head Rapier
Studs are suited for automotive applications, as well
as for use in aerospace/aviation, transportation, engineering,
office and computer equipment, and white goods assembly.
Handle offers easy installation
PROBLEM: In applications where access to the
rear side of a door or panel is limited, a handle that
mounts from the rear can be difficult or even impossible
to install. The process can involve removing the gasket
from the rear side of the door, installing the handle,
then re-installing the gasket. Potential results: frustration,
extra work for manufacturers, and damage to the customer's
SOLUTION: A new grab handle gives users the
option of either front or rear installation. Mounting
the handle from the front requires no gasket removal,
making installation quick and easy, and saving on both
time and installation costs, says manufacturer Southco.
The mounting hardware is completely concealed by a snap-on
cover, which can be stylized with custom colors or company
name and logo. The non-corrosive handle is made of tough,
high-impact ABS and has a maximum working load of 775N.
APPLICATIONS: The grab handle is suited for
use in many types of cabinets, including gasketed refrigerator
cabinets, as well as in furniture, medical equipment,
power boxes, and enclosures.
Rivets hasten fastening, save money
PROBLEM: When large quantities of the same type
of fastener need to be installed in quick succession,
time and installation costs can skyrocket.
SOLUTION: Patented SCHWINGMETALLr rivet mounts
are attached by riveting tongs and a customary blind
rivet, which is much faster than screwing, says manufacturer
ContiTech. The rivet mounts comprise metal parts completely
surrounded by natural rubber, which eliminates potential
corrosion problems. The mounts can withstand pressure
and shear force, and provide the same anti-vibration
characteristics available with SCHWINGMETALL mounts
with a threaded screw. They damp harmful shocks, insulate
machine vibrations, reduce accelerations, and protect
against unwanted noise.
APPLICATIONS: SCHWINGMETALL rivet mounts can
be used in the automotive industry and in road construction,
where they hold noise protection walls in place. In
equipment manufacturing, the rivet mounts can be used
to fasten sheet-metal parts, linings, and control cabinets.