Stud

Automotive & industrial

Our client was facing a line stop on an exhaust stud they were importing from England and enquired if we had an equivalent. At the time, we were supplying the same stud to another of our clients, a metal stamping company, albeit in a different material. Our automotive client purchased 5000 from us, with no deviation or paperwork being requested.

It then turned out that the studs were turning in the flange when tightened on the automotive line. This did not make sense as the flanges were being supplied to our automotive client by our metal stamping client – the same company that supplied another automotive company with flanges and BTI with studs, neither of which had any problems.

Similarly, the same studs with an electro galvanised finish were being supplied to the initial automotive client for a different car model with no problems.

Our representatives requested a line inspection and found that the two studs for the different models were being pressed in with different processes. One was utilising an electric press while the other employed a hydraulic press.

The electric press was not pushing the stud in far enough as it had not been calibrated for the original material used. Before informing the client of our findings, who was insistent that our stud was the problem, we arranged with our Sales Manager to visit our metal stamping client to try to get more clarity on the matter.

Our metal stamping client was using an eccentric press, but stressed that whatever machine was used must be calibrated. This client had a full test laboratory with machines that tested the pull out and torque (stripping) of the studs. We had seen no such testing at the factory of our automotive client who was facing issues with the studs.

The automotive client was informed of our findings and approval of our stud was obtained and consequently supply continued. The client then sent a quality team to our metal stamping client on a fact finding mission leading to the calibration of the press and the end of the problem.

Weld nut

Production engineering

A production engineering company was importing a grade 8 nut and was having problems with welding it onto a pressing, so came to us looking for a solution and possible supply. They had called in welding machine experts to check settings and other potential causes of the problem, but to no avail.

Our representative visited the site to check out the pip sizes and look for any obvious defects or variation from the drawing, and found none. This led to an investigation on the material being used. It was found that the material’s carbon content exceeded the recommended 0.25/0.28% carbon for weld studs or nuts.

Our representative then submitted a proposal to supply the nuts in 10B21 material, heat-treated to Class 8, which was accepted and proved successful.

She has had various other similar incidents where weld stud or nuts are zinc plated, solving these issues by applying a sealer which effectively insulates the fastener causing the welding problems.

Blind rivet

Security gates

A leading security gate manufacturing company was using a 4.8mm aluminium blind rivet on an expanding security gate. However, they were finding that the grip range of the blind rivet had setting parameters that exceeded the required precision of distance at which they needed to set the rotation ability, this being at the cross members of the expanding gate.

The natural variation of the steel hardness in the mandrel of the rivet and the aluminium hardness in the body combined to allow for a broader range of setting distance parameters. Blind rivets are essentially designed to set at full tightness and hence clinch the two adjoining parts tightly without movement.

In order to overcome this, Quintin Terreblanche and the team changed two very specific designs in the rivet.

The 4.8mm rivet aluminium body was manufactured on a 4-stage heading machine, allowing a step to be built into the inner diameter of the rivet body. This process now required a thinner steel mandrel made of stronger wire, as the step in the rivet body made a narrower hole than the normal mandrel diameter for a 4.8mm rivet. The mandrel head was forged to be slightly larger and the notch break a little deeper.

Now, when the mandrel was pulled to set the rivet, it would only go as far as the inner step – at which point the larger mandrel head and deeper notch snapped the mandrel and set the rivet at the required length.

The customer uses over 500 000 of these rivets per month, and this design has been in use for more than 5 years.

Various attempts to reverse engineer this product in China, Taiwan and India have failed.