SUMMER 2023

160
THE DISTRIBUTOR’S LINK
BRUNO MARBACHER THREAD-FORMING SCREWS FOR PLASTICS from page 134
PLASTITE SCREWS
They were the first screws that were used specifically
for the direct fastening into plastic parts. The original form
had a tapping screw thread. The thread cross-section
is trilobular. The trilobular thread cross-section permits
relaxation of the plastic in the flat parts of the thread
cross-section during and after assembly. Tensions are
reduced. The risk of stripping is low.
The further development is the Plastite 45 with a 45°
flank angle of the thread. The extra wide thread spacing
and more intense thread angle of PLASTITE® 45 screws
keep induced stress to a minimum during the thread
forming operation.
Plastite 48-2 screws have a trilobular body like Plastite
45 screws, but are furnished with a double lead, two-start
thread. The steeper helix angle allows higher breaking
torque normally resulting in a larger difference between
breaking torque and driving torque.
asymmetrical thread form (10° on the load flank) provides
a low installation torque and very efficient fastening. This
thread design minimizes radial stresses and too much
material displacement.
BOSSCREW
BosScrew is the only screw specifically designed not
to loosen in plastic applications. The BosScrew has small
depressions on thread’s load flank, they interlock in the
plastic part as the screw is being tightened. It will remain
secure over time, despite temperature changes and under
vibration. According to the manufacturer, BosScrews
provide as much as four times the holding power and
a drive-to-strip ratio 66% better than the leading screws
being used in today’s plastics.
REMFORM SCREW (REMFORM II)
After the patent of the Plastite was expired the
Remform screw was developed. The thread profile of the
Remform screw is tapered. Thus, the initial driving torque
is low. The rounded flank enables a good flow of the
displaced plastic.
The steep flank, directed towards the head, improves
the pullout force, and simultaneously gives a high breaking
torque. The assembly reliability is high.
POLYFAST SCREWS
Polyfast fasteners have a unique thread design, which
provides remarkable performance in plastic. The 40°
CELEPLAST
Celeplast has a thread-forming thread with a thread
angle of 40º, which provides a 30% reduction in radial
tension during the threading forming process, avoiding
damage to the plastic.
CELOspArk® screw is a further development of
CELOPLAST screw. The 30º thread design generates less
radial tension on plastic reducing the problem of boss
bursting.
CONTINUED ON PAGE 168