French manufacturer of trapezoidal
or ball screws and nuts

Cold threading
process

The 2 knurling wheels get closer to the part by turning in the same direction to carry it along in rotation and to penetrate the material until it deforms and reproduces the desired shape.

The thread of our screws rolled by cold forming comes from deforming the material under the force exerted by the two knurling wheels bringing with it the opposite shape of the part to be machined. The material is then bent and takes the shape of the knurling wheels, so it leads to an expansion of the part’s diameter. The two sides of the material run right to the depth of the knurling wheel groove to finally meet.

The zone where the two sides meet makes a crease of which it is possible to adjust more or less the closure. In the industry, it is called « buttock effect » and it is an efficient method to identify rolling made by cold forming.

This process therefore presents numerous advantages compared to other systems based on material removal.

• Material fibers deformed but not cut
• Considerable gain of material as the roughing Ø is inferior to the finished Ø (no chips versus machining)
• Increased mechanical resistance: the material is hardened on the surface by increasing its mechanical resistance)
• Improved surface quality versus machining (no marks on the parts due to wearing away the tools)
• Noticeable increased high precision of thread versus machining
• Possibility to make specific shapes
• Possibility to roll long lengths
• Reduced production time versus machining
• Reduced production cost as the rolling is made in a single production
• Cost reduction versus rolling