Ask any manufacturer why they changed from traditional fastening methods such as weld nuts, blind rivet nuts or loose hardware to self-clinch alternatives and they could give a number of different reasons. If the initial idea came from the engineering department, then the main reasons would be to improve the quality and robustness of the fastening, or it could be the flexibility to secure a wider range of materials. If the change was prompted by the production team, then the most common reasons would be to increase manufacturing throughput whilst also reducing production costs.
Typically, self-clinch fasteners deliver improvements in all three key objectives of an efficient manufacturing process: throughput, product quality and assembly cost.
Self-clinch versus conventional fasteners
In an existing manufacturing process it can take a full 60 seconds for the assembly operator to pick up, correctly orientate and place a blind rivet nut on the installation tool. A work-piece that uses a total of 20 blind rivet nuts would, therefore, spend 20 minutes on this single stage of its production process.
A switch to self-clinch fasteners with a suitable installation press would reduce the assembly time to just 10 seconds per fastener. This one simple change can make a significant contribution to increasing production throughput and reducing the number of operators required on a manual assembly line.
There are similar time- and cost-savings when self-clinch fasteners are used to replace weld fastenings. Here, the change would also eliminate the additional process of thread cleaning, following the welding process – alongside the cosmetic benefits associated with self-clinch fastening.
The total savings realised by switching to self-clinch fasteners are dependent on the existing type of fastener and the production process. Typically, PennEngineering has been able to demonstrate that a saving of at least 27% can be achieved when replacing loose fasteners; savings of 40% for welded fasteners, 54% for blind rivet nuts and up to 58% for rivet bushes.
Although these cost-savings are considerable, they are not the only benefit of switching to self-clinch fasteners. Unlike the alternatives, the majority of PEM brand self-clinch fasteners are heat-treated to produce a harder and more durable fastening – providing the `load bearing` thread that many designers seek. They can also be used to fasten metal sheets with thicknesses down to 0.3mm, where the use of conventional fasteners would not be possible.
Typically the transition from conventional to self-clinch fasteners starts with a cost/benefit analysis or a technical seminar. The cost-benefit analysis examines the existing manufacturing processes used to install conventional fasteners and provides a detailed breakdown of the potential savings in the manufacturing and labour costs, throughput and manufacturing yield. This can be followed by a live on-site trial using an existing press or utilising the Pemserter range of manual and automatic installation equipment designed and manufactured by PennEngineering. This system approach to customer assembly challenges is a compelling cost-saving measure that can deliver the competitive advantage many manufacturers seek.
Many manufacturers, in industries such as telecommunications, computing, medical, automotive and aerospace, have already switched to the PEM brand of self-clinching nuts, studs, spacers, standoffs and access hardware. The same advantages can, however, be realised by virtually any other industry in which conventional fasteners are used.
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