Socket & Allied

If it's not a standard it must be a special!

Special fasteners will be made to a drawing and a specification so provide us with as much information as possible. The application is also useful as this might influence the manufacturing process.

Special fasteners will often conform to an International Standard and Specification but not comply in just one or two dimensional aspects; or they are not a size within an inventory range.

It is advisable and good practice to provide a drawing and full specification for us to work to or a sample.

Finally, do ensure that the drawing is the latest issue. It it costly and potentially dangerous to manufacture to the wrong drawing and specification.

Heat Treatment

It is often necessary to heat treat fasteners after manufacture; either to enhance their strength properties or to remove internal stresses in the material that develop during the manufacturing process.

Hardening
- Most steel fasteners require hardening to give them strength. This is achieved by heating them to a temperature of between 750° & 860° Celcuis depending on the material.
- Quenching in Oil rapidly cools them causing them to become hard.
- Oil quenching produces a black finish caused by the oil oxidising at high temperature.
- It is also possible to heat treat stainless steel by using the 4 Series Grades

Annealing
This process removes the internal stresses in the fasteners and makes the material more ductile and pliable. The process consists of heating the fasteners to a selected temperature depending upon specification, followed by a slow and carefully regulated cooling to allow the material to stabilise.

Quality Control
- After heat treatment, the matallurgist will take selected samples from each batch for microstructure analysis and overall examination.
- The results will be recorded and the samples retained in case of future need for traceability purposes.

Thread Forming Screws

From the simple woodscrew to the Rolled Thread Machine Screw and then onto the Self-tapping Screw, the next advance was the evolution of thread-forming screws.

Efficient automated assembly and the quest for "in-place" cost improvement created a demand for fasteners that form their own thread during insertion. The ability to emilinate a separate tapping operation gives immediate cost savings.

Many of the thread forming fasteners have a "trilobular" diameter profile; this enables the fastener to roll form a thread as it is inserted into a plain, pre-prepared hole.

This thread forming capability provides a cintinual rolling action that assists grain-flow as the fastener is inserted into the hole. The thread geometry in the hole is therefore, perfectly matched to that of the fastener. As a result, the jointed assembly is stronger and more resistant to vibration loosening than other types of fasteners.

Most thread forming application are found in the joining of steel and plastic parts.

Thread forming screws are available in steel & stainless steel. Steel screws are normally supplied zinc plated. Both materials are supplied together with a lanolin, wax or other lubricant coating.

As with self-tapping screws stainless steel self-tapping screws may not be suitable for use with hard materials due to the fact that stainless steel fasteners cannot be hardened after manufacture.

Most thread-forming screws generate standard Metric or Unified threads. This allows a standard rolled thread machine screw to be substituted if needed.