NOTE: REMFORM® Original screws are a legacy product. We now recommend REMFORM® II™ fasteners for plastics applications.
The REMFORM® screw is a round-bodied thread-forming fastener with a unique thread form, specifically designed for today's wide range of plastics. REMFORM® screws not only form well-developed threads in pliable material, but are also competent for demanding applications utilizing the latest tough engineering grades of plastics. The same principles that make REMFORM® fasteners ideal for engineering grades of plastics make it equally suitable for other ductile materials such as wood and soft metals.
The REMFORM® Screw's Unique Thread Form
The steep trailing flank on the REMFORM® screw's unique asymmetrical thread form is engineered to resist pullout, whether it be applied by a tensile load or induced by torque. When a threaded fastener is tightened, the trailing flank has to resist being pulled toward the direction of the head. Nearly all the load is between the screw's trailing flank and the adjacent nut thread's flank. The leading thread is most influential in forming the mating thread. The narrow angle intercepting a radius form on the lead flank promotes efficient material displacement and flow.
The REMFORM® Screw's Strength
The REMFORM® screw is strong. With a higher torsional strength than many spaced thread fasteners, REMFORM® is able to utilize this strength along with its superior thread forming ability to allow deep lengths of engagement. These deep lengths of engagement allow REMFORM® to out-perform other spaced thread screws since more holding power can typically be obtained by increasing the engagement length rather than increasing the diameter of the screw, which results in relatively small performance gains, at a higher cost.
The deepest engagement a screw can be inserted into is typically the point where the nut threads are formed to a strength level where the screw fails by breaking rather than the hole stripping. With weaker screws these deep engagements are not possible since the thread forming torque for such deep engagements will approach the breaking torque of the screw. Even when engagements are not deep enough to break the screw, REMFORM®screw's high stripping torque and low thread forming torque provide a wide comfortable margin in which the seating torque may be chosen.
Thread Forming Torque
The unique thread form and sharp tipped threads provide low thread forming torque by efficiently moving and displacing material.
High Failure Torque
In applications where screws fail by torsional breaking when subjected to ultimate torque loads, the REMFORM® fastener's high torsional strength assures a high failure torque. In applications where the failure is due to the fastener stripping the nut threads, the steep trailing flank puts most of the resisting force in an axial direction as opposed to a radial direction, to increase the resistance to stripping.
A wide torque range between thread forming and failure torques facilitates assembly by allowing an assembly torque that provides a comfortable margin between the assembly and failure torques. This wide torque range assures that all screws are fully tightened, eliminating the possibility of stripped assemblies.
Reduced Hoop Stress
REMFORM® screw's radiused leading thread flank reduces hoop stress by minimizing radial forces during thread forming and upon the tightening of the fastener. The trailing flank's steep angle transfers most of the resultant forces developed in the tensioning of the fastener along the screw's axis, minimizing the boss bursting radial forces.
The REMFORM® screw was developed with total quality in mind - a quality design. Many fasteners are developed with little regard to the manufacturing processes used to produce fasteners and the limits these processes impose upon the fastener design. The result is designs that cannot be made efficiently. This results in fasteners that do not maintain their intended shape along the whole shank, have poorly filled out thread forms, or deviate erratically from the intended design specifications. These deficiencies usually result in erratic performance, hampering attempts at quality assembled joints.