Thread-forming screws
for cost-effective direct screw connections
Advantages of thread-forming screws
Thread-forming screws create their nut thread automatically during assembly by forming the nut material. This makes it possible in many cases to use components directly without an existing nut thread, which considerably reduces the overall costs of mechanical connections. In particular, the connection costs can be significantly reduced, as the thread cutting or thread forming step is no longer necessary and there are no annoying chips. The screws can be used directly in punched, drilled, cast or laser-cut holes. Thread-forming screws also offer significant advantages in terms of process reliability: the material hardening in the thread results in a higher load-bearing capacity of the overall connection. The backlash-free contact between the bolt and the nut thread and the necessary insertion torques result in increased resistance to loosening, which often makes it possible to dispense with screw locking devices.
The thread-forming screws produced by ESKA® are patented/licensed and registered trademarks of CONTI Fasteners AG. They are designed to meet the requirements of various applications and materials and are therefore available in different geometries, materials and surfaces. Direct fasteners always require an optimized interaction of component, fastener and assembly and thus a specific design of the screw for the respective application. For highly stressed and special applications, we always recommend an exact analysis of the connection and the required properties, for which our development department will be happy to help.
Applications
Direct fittings can be used with a wide range of nut materials. All metals and plastics with sufficient ductility and a material strength of up to approx. 650 MPa are suitable. A distinction must be made here between direct screw connections in metals and in plastics: For metals, especially steel, the screw must be very hard in the groove area. This can be achieved by tempering for high strength or by surface hardening processes such as case hardening or partial inductive hardening. The latter also make it possible to use thread-forming screws for connections subject to high static and/or dynamic loads. The thread profile corresponds to the profile of metric screws and is compatible. For plastics, slim, widely penetrating flanks with an increased pitch are used. The strength of the hardened and tempered screw is sufficient here; special hardening of the surface layer is not usual.
Overview of the different screw types
Steel / cast iron / aluminum
The TAPTITE 2000 ® and TAPTITE ® PRO™ thread-forming screws are designed for direct screwing into metals. The TRILOBULAR ® screw cross-section of both screw types is characterized by a triangular basic shape with a constant rolling diameter, whereby the large radius of the inner circle is opposite the smaller one. The TRILOBULAR® screw cross-section guarantees a low thread torque and, in addition to excellent resistance to loosening due to vibration, a reduction in overall assembly costs.
- TAPTITE 2000 ®
- TAPTITE® PRO™
Magnesium / low-strength aluminum
High-strength ALUDRIVE ® aluminum screws from ESKA ® are the optimal solution for the secure connection of magnesium-aluminum components. These can also be manufactured in all standard TAPTITE ® geometries. Preload losses due to thermally induced additional stresses are minimized by the very similar expansion coefficient and contact corrosion is almost completely avoided even with uncoated screws. The thread-forming version now also enables the direct screwing of sufficiently ductile magnesium alloys and low-tensile aluminum alloys.
- TAPTITE® PRO™ or TAPTITE 2000 ® as ALUDRIVE ® version
Sheet metal materials
The FASTITE 2000 ® geometry was specially developed for the assembly of sheet metal materials. It enables the reliable assembly of sheet metal thanks to a special thread type with double helix geometry and has a very good ratio between overtorque and screw-in torque due to its trilobularity.
- FASTITE 2000 ®
Plastics
REMFORM ® II™ screws have been specially developed for screwing into plastics. The coordinated geometry of the asymmetrical thread ensures excellent assembly properties with low mechanical stress on the screw bosses of the plastic component.
- REMFORM ® II™
Locking screws and special threads
POWERLOK® II™: The trilobular basic geometry in combination with a reduction of the flank angle in the area of the thread tip creates a clamping effect with existing metric nut threads, which is also maintained with multiple screw connections.
- POWERLOK® II™
Special threads and products patented / licensed by CONTI Fasteners AG in the ESKA® product range:
- CORFLEX®, DUO-TAPTITE ®, EXTRUDE-TITE ®, FASTITE 2000 ®, KLEERLOK®, KLEERTITE®, MAGTITE® 2000™, PLASTITE®, POWERLOK®, POWERLOK® II™, REMFORM ®, REMFORM ® F´´, REMFORM ® II™, REMFORM ® II™F´´, TAPTITE 2000 ®, TAPTITE 2K®, TAPTITE II ®, TAPTITE® PRO™, TRILOBULAR™, TYPE-TT®, TYPE TT 2000 ®, TYPE TT 2K®
Product designations with SP”™ have a lower number of threads and are particularly suitable for soft materials such as aluminum alloys (TAPTITE® PRO™SP”™ and TAPTITE 2000 ® “SP‘’™).