cold forging

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Clevtec

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In  2008 when the world stopped due to the financial crash, we had to re-evaluate our business model as we realised that if people didn’t want the fasteners we manufactured at Clevedon, we were pretty much sunk. As a result we created Clevtec. Clevtec is a trading arm of Clevedon Fasteners Ltd and unlike Clevedon who are a purely a manufacturing entity, Clevtec is able to buy and sell product all over the world, as long as it made a return. This meant that as well as fasteners, Clevtec could venture into other parts of the fastener market, that we were unable to make at Clevedon.

Clevtec soon found that there was a latent demand of high quality threaded fasteners, particularly if they were of UK origin and so in 2012 we purchased a company called Blakeacre who specialised in high quality threaded fasteners and they became part of Clevtec. In addition to threaded fasteners, Clevtec over the years has got into Commercial Vehicle brake shoe platforms and various types of setting machines, the latest of which being spin riveters.

Clevtec’s latest market offering is a range of services that we believe our existing an new customers will find of interest. Over the past year we have been developing with a selected number of existing customers, two specific services:

 

Supplier reduction service

Design Support service

We are now in a position where we are able to offer these services to other customers. The details of these services will be on our new Clevtec Services web site and will be the subject of further Blogs in the future

Clevtec Services  https://www.clevtecservices.co.uk/

Contact us on 0121-378-5967

or email me on steve@clevtec.com

Designed to Fail

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In this age of high tech, computer based design. A growing problem is becoming obvious to us here at Clevedon. As you know, whilst we do some very clever cold forgings and self-piercing products, our main business is based on the humble rivet. Solid Semi-Tubular and Fully tubular rivets. Some of you reading this blog may not even know what these products are or will confuse them with “pop” or other blind rivets

Therein lies one of the problems with modern design techniques. A confluence of two factors, demise of “old style” apprenticeship’s where some of our best engineering talent learned their trade and the rise of the computer savvy, iPad literate younger generation, many young designers have not been taught some of the most basic, fundamental engineering techniques.

This is not their fault, most CAD systems are great at producing designs drawings. Unfortunately, only certain techniques are included in the various wizards and “look ups” which mean that only certain outcomes will be produced.

Quite often these unintentionally, pre-defined outcomes are very difficult to productionise and more importantly very costly to manufacture.

We have had experience of being told by very well meaning designers that our suggested fixing proposal will not work because their Finite Element Analysis (FEA)testing show that the rivet will fail at a particular load. This despite that fact that in our long history (we began business in 1939), we have never encountered a failure mode of the type the FEA predicted would happen. To prove the point, we undertook practical testing to discover what happens in actual practice. The rivet did not fail.

Drawings are sent to us where in order to realise the designers dream, the product needs to be turned, milled, drilled, ground etc.  Each operation results in expensive individual set up and run times and thereby the final product is very costly to manufacture, at which point some very innovative designs are dropped because they do not make economic sense to peruse.

Powder printed samples are very good straight off the CAD system, but are incapable of predicting that the whole project will fail due to the lack of basic engineering input at the beginning. The old adage rubbish in, rubbish out, still holds true. All of these very sophisticated, technologically advanced  CAD and FEA systems all have the same fundamental, inherent weaknesses and results in the waste of large amounts of time, money and company resources, to say nothing of the potentially game changing design concepts that never come to fruition.

Here at Clevedon (the parent of Clevtec) we do not claim to have all the answers, but we are very good basic engineers. Having had to fight against overseas competition that has destroyed many good UK engineering companies we do have a very good track record in providing low cost, practical, innovative solutions to seemingly intractable design issues.

For the above reasons we have introduced a “Design Support Agreement” to work with designers to put some of the practical elements back into the design process that don’t come straight out of the can. We have found this has the most beneficial effect when we are involved early on in the design cycle but have also been able to re-engineer designs that have got into difficulty (usually cost difficulties).

Please contact us and ask for Steve Hardeman and we will very soon be able to let you know if we are able to help.

Engineering 101

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Riveting is one of the oldest forms of fastening

Solid rivets have been found dating back to the Bronze Age (ended 800BC)

You will have seen rivets hidden in plain site on bridges, ships, Aircraft and Trucks to name but a few common applications

 

bridge

 

Rivets are formed by a process called Cold Forging, this process produces no waste as the head of the rivet is formed by upsetting the shank of the rivet. This ensures the grain flow of the material remains in-tact thus strengthening the fastener.

The rivets are inserted in the material to be fixed together and “set” by deforming the end of the shank of the rivet to product a permanent fix

rivet 1

 

The more popular, semi-tubular rivet is set in a similar way but require a lot less setting load and provides a “Clinch” fix which pre-stresses the material

rivet 3

Many engineers are unaware of the advantages or even the function of rivets, tending instead to fall back on threaded fasteners which are more widely available.

The most recent development in Riveting is the self-piercing rivet, where you do not need a hole in order to rivet two materials together. This process is now commonplace in state of the art automotive manufacturing plants. JLR being pre-eminent in this regard

Self_Piercing_Rivets_sketch[1]

The process used to produce these fasteners has been developed in order to use the same manufacturing technique, cold forging, but to enable finished components to be forged outright, with the same benefits, no waste and a very strong structural integrity

forg 1

 

We are happy to help customers or prospective customers with any queries that may have regarding riveting or cold forging. We have recently helped a number of companies by producing and riveting prototype designs for them.

We have been in this business since 1939, over that time we have provided innovative, low cost solutions to many fastening and cost reduction requirements, thrown at us by our customers.

In the first instance, contact me, Steve Hardeman either by e-mail (steve@clevedon-fasteners.co.uk ) or by telephone on +44(0)121-378-0619

PT Screws

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Screw3

The growth in the use of PT Screws is driven in part by the need to reduce the total weight of an increasing number of component assemblies, either new design or redesign.

The type of plastic selected for the required component performance means that it is essential to use a fastener that maximises clench properties by ensuring high strip out torque values and in many applications prevents loosening due to vibration. PT screws are the ideal fastener for such applications where fasteners such as self-tapping screws for steel applications would fail due to their wide flank angles and shallow threads

Clevtec’s ever increasing range of PT screws manufactured at our two plants in Birmingham UK, currently cover 2.2mm up to and including 6mm diameter PT Screws in metric and imperial sizes (including Tri-lobe).

There are so many versions of PT screws available, we tend to manufacture to customers specific requirements

Ideally we would like a fully detailed drawing of what you require together with some idea of  the volumes you will be ordering

In the absence of a drawing, we need to know the thread size and type (Imperial or Metric), what type of head you require, Pan Head, Pan Flange, Countersunk, Mushroom etc. Do the heads need to be marked? what type of drive do you require for the screw, we can do manufacture most standard forms in common use

The trickiest area in the absence of a detailed drawing is heat treatment and finish. again there are many different requirements that can trip up the unwary. Is the product property class 10.9 or is it a through harden/case harden treatment? All our heat-treated parts that require zinc plating  (the most common finish) are hydrogen de-embrittled. The de-embrittling time can vary depending upon the heat treatment hardness that is specified

If you need any advice please call us

Screw1

 

What do you mean,it doesn’t need a hole?

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SPR4

Self Piercing Rivets

Self piercing rivets can trace their ancestry back to the humble Bifurcated Rivet (http://www.clevedon-fasteners.co.uk/products/bifurcated-rivets) developed by the Bifurcated and Tubular Rivet Company (B&TR). A bifurcated rivet was designed to firmly fix wood together (packing cases being a good example). It works by the rivet being pushed into the two layers of wood, due to is slot angle, when it reaches the second piece, the rivet flares, causing the joint to clinch firmly, much stronger than nails and much quicker than screws.

Someone at B&TR (the argument as to who is lost in the mists of time) thought, what if we could do that with a semi tubular rivet ( http://www.clevedon-fasteners.co.uk/products/semi-tubular-rivets), productivity could be increased remarkably as there would be no reason to pre-drill the holes when fixing together sheet metal. The Self Piercing Rivet (SPR) was born (http://www.clevedon-fasteners.co.uk/products/self-piercing-rivets)

SPR’s can fix multiple layers of sheet, even dissimilar materials without a hole (therefore no danger of water ingress) plated or painted sheets can be riveted together as the SPR setting process creates no heat (unlike conventional spot welding therefore there is no residual spatter) and so SPR riveting is an environmentally friendly process.

SPR2

The benefits are obvious, no preparatory holes to be drilled, environmentally friendly, dissimilar sheets can be clinched (steel/Alum, Alum/Plastic etc.), no water ingress,

Modern setting equipment means the setting loads for each rivet can be monitored and recorded for quality control purposed

The amount of applications is rising every day, from Automotive to humble Hen House covers (yes Really!!)

If you need any further information, on these or any of our products, please contact me on 0121-378-0619 or e-mail me at sales@clevtec.com