Fastener security: three things to consider

When a manufacturer is considering security issues around fasteners, generally there are three aspects:

* The ability of the fastener to securely do its job and withstand problems such as vandalism.

* How secure will the fastener be in service, how for example will it seal or retain components and/or fluids?

* How confident can I be in my selection and my supply chain?

These are vital matters addressed by Kevin Moorcroft and his team at Challenge Europe, for example they are delighted to have in their portfolio the Hafren range of security fasteners – a range of anti-vandal, anti-tamper screws and nuts proven in applications from architectural and street furniture, to marine and industrial equipment.

Vandal resistant fasteners such as 2 hole headed (otherwise known as pignose or snake eye) A2 stainless screws, bolts and self-tappers provide a versatile and clean look to
installations while deterring vandals and keeping installations safe.



Likewise, shear-nuts in zinc plated steel, galvanised, A2 and A4 stainless.

Other important items include 6-lobe driven threaded fasteners in A2 stainless steel with centre pin, in self-tapping, machine screw, self-drilling, barrel nut and floor anchor formats.

Both countersunk and dome headed types are available.

Regarding security of retention and sealing, Challenge Europe offer exceptional performance with Dubo products which flow into the threads of the bolt and the nut, where they create a particularly effective frictional resistance with the bolt.

This action prevents rotation of the retaining ring around the bolt, by wrapping around the flats on the nut and thereby effectively prevent the nut from loosening by filling all free spaces, while sealing against leakage.

Applications range from use in preventing leakages from transformer oil reservoirs to  more demanding roles within the power generating industry and elsewhere.

Because DUBO Retaining Rings possess plastic-flow characteristics they absorb vibrations arising in the bolt assembly and exhibit excellent sound-deadening properties and durability. Thus they neither deteriorate nor wear and may be re-used again and again without loss of performance.

DUBO Retaining Rings are chemically resistant to Alkalis, to solutions of neutral inorganic salts, also to oils, fats, petrol, benzine, alcohol, acetone, diluted acids, and sea water, they are consequently able to prevent electrolytic corrosion between two different metal surfaces and prevent fatigue in the bolt material while  insulating and protecting the surfaces.

An addition to the DUBO system is the DUBO-toothed collar ring which is intended for use in combination with high quality steel nuts (8.8).

The toothed collar ring enables any desired bolt tension without damaging the DUBO-retaining ring through high bolt and nut loads, this design permits the use of any nut as a locking nut, which can then be re-used.

Constraining the DUBO-retaining ring into this toothed-collar ring ensures that optimum deformation of the DUBO-ring is obtained after tightening the nut which provides a secure and long lasting locking and tightening effect according to the DUBO principle.

This high level of product performance is of little value however unless backed by an experienced team working to BS EN ISO standards – manufacturers’ confidence in their supplier is crucial to the reliable consistent output of any production facility.

Confidence which stems from the ability to work in partnership with regard stock holding and supply control which may be offered from a central managed site covering production line restocking of fasteners, inventory control – measurement, stock re-ordering, kit and component supply, and single point invoicing.

Site management enables a supplier to maintain optimum stock quantities and production system integration ensures supply chain capabilities within preferred production systems, eg Kanban, Lineside Supply and Vendor Managed Inventory (VMI).

A process which may additionally include supporting the engineering operation by initiating the supply chain, working from engineering drawings to determine the components/assemblies required.

Security and confidence come from partnering design and commissioning new component tooling for improved manufacturing efficiency.

Thus by controlling existing tooling your fastener partner is able to audit and maintain an inventory, including a full logistical history for each item.

Managing quality control

Managing quality control in this way they can take responsibility for the inspection, monitoring and acceptance/rejection of components.

Ultimately as concept consultants your fastener supplier can advise on optimal design-for-production (DFP) values at the product concept stage and provide specification consultancy with pre-production advice on the handling of components, kits and sub-assemblies.

This allows greater confidence in the development/production process leading to reliable high quality outcomes.

Further along the product lifecycle into product enhancement, production engineers will want to look at  on-going product improvement – a process that can be made easier by a supplier who can suggest components of alternative materials or how to reduce component counts and shorten assembly times.