REMFORM® Screws
Designed Primarily for Plastic Applications
The
REMFORM® Screw is a thread rolling fastener with a unique thread form
to provide superior performance in today's wide range of plastics. The
asymmetrical thread minimizes radial hoop stress to reduce boss
bursting. The narrow tip angle also reduces stress in the plastic nut
member.
The Unique Radius Flank™ Thread Form
Both
REMFORM® Fasteners employ the Unique Radius Flank™ asymmetrical thread
form shown in the drawing to the right. The leading thread flank is most
influential in forming the mating thread. The intercepting radius form
on the lead flank is there to promote efficient material displacement
and material flow. The steep trailing, or pressure, flank which opposes
the fastener head is engineered to resist pull-out forces, whether they
be applied by a tensile load or induced by torque. This unique thread
and its narrow tip angle efficiently displace material and therefore
require minimal energy to form an internal thread. The steep trailing
flank with excellent material contact results in a high resistance to
the internal threads stripping. In applications where the failure mode
is fastener fracture, the high torsional strength of REMFORM® fasteners
ensures a high failure torque.
Reduced Hoop Stress
When a threaded fastener is tightened, nearly all of the axial tightening load, designated F,
is opposed by the trailing, or pressure, flank of the screw and the
mating thread flank of the internal thread. The narrow 12.5° angle of
the pressure flank transfers most of the resultant tightening load in
the axial direction, Fa, minimizing boss bursting tendencies created by the radial force, Fr. The axial force, Fa, is over 4.5 times greater than Fr, the radial force.
Optimal Material Flow
The
radius thread flank of the REMFORM® screw thread minimizes radial
forces during thread forming, resulting in low thread forming torque.
The asymmetrical thread form of the REMFORM® fastener produces
asymmetrical opposing resultant forces off the thread flanks during
thread forming, creating improved material flow. The picture to the left
shows the material flow towards the thread root which results in
greater material contact along the pressure flank of the fastener,
increasing resistance to stripping. The reduced contact along the
leading flank reduces friction during thread forming and lowers the
thread forming torque.
Easy Assembly
Low thread forming torque, when coupled with high failure torque, results in a wide, safe assembly torque range.
 
 
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