Posted to News on 23rd Nov 2014, 00:00
Securing bolts from shock and vibration
From the rail industry and agricultural machinery to construction equipment, shock and vibration are key issues for fasteners. But then there is the requirement for theft proofing in applications such as outdoor furniture. Now there is a single, versatile, reusable fastening solution suitable for such applications.
>Shock and vibration are major issues in a raft of industries, impacting on the long term security of fasteners employed. At the same time, many applications require a degree of protection against tampering. In some applications, thread locking may be a solution, but this can impact on reusability. Alternatively, special formats of fasteners might suggest themselves, but suppose yours is an application where, ideally, you'd simply want to use a standard bolt, washer or nut?
>Now there is a solution, in the form of the SBS (Secure Bolt System) from IEC - a patented and reusable self-locking system that provides ultimate fastening security to bolted joints. It has been tested to stringent industry specifications by accredited test laboratories worldwide to prove its effectiveness in applications subject to extreme vibration. The system provides an excellent solution to manufacturers experiencing the loosening of their fasteners in applications prone to vibration. It provides a mechanically based, self locking, reusable fastener system that will not lose torque under high vibration and heat conditions.
>Further, the tamper-proof design provides protection against theft of equipment. IEC says the SBS is unique in providing security against tampering as well as vibration resistance.
>The SBS fastener consists of a standard hexagon shaped nut or bolt and washer that includes a specially designed wedge integrated into it design. Once the bolt is tightened, the washer and bolt head fit together. The nut or bolt cannot back off as its acts as a 'wedge' and will put a downward force onto the metal as it attempts to back off, due to the opposing wedges on the nut or bolt head and washers. Two designs of washer are available: a standard hex design for applications where removal with standard wrench is required; and a round design requiring a special indexed socket for removal for tamperproof applications.
>Both the underside of the hex bolt head and the nut are designed with wedges which correspond with the wedges found on the washers. To use the SBS, the wedges on the washer should be facing the wedges on the nut and bolt head and the flat part of the washer should be facing the surface of the material that is being fastened. Using a standard wrench or socket turn the bolt clockwise to tighten ensuring that the wrench or socket is engaged on both the bolt head and washers at the same time. Once the bolt and washer are tightened to the desired torque, remove wrench or socket from the washers and proceed to tighten the bolt head until the wedges on the bolt head sit flat up against the wedges on the washer. This ensures that the fastener is fully engaged.
>Removal of the nut/bolt requires a different approach depending on which type of washer is used. Using the hex washer with the nut/bolt allows the fastening to be loosened using a standard wrench or socket. The round washer however cannot easily be loosened using the same standard tools. In this instance the use of a specially designed SBS indexed socket is required. This has the benefit of adding an 'anti-theft' element to the assembly.
>As well as being used in conjunction with a mating bolt or nut, the SBS can be used as a washer based system by using a pair of washers back to back to create the mechanical locking effect. In this way it is a truly versatile system in that you can take advantage of its basic features without changing any existing bolts or nuts.
>The SBS has been extensively tested for performance under vibration under JQA Vibration Laboratories, SGS Vibration Laboratories and NAS 3350, and has proved vastly superior to either hex nuts with conical washers or normal nuts with flat washers, maintaining a constant torque whilst the other solutions displayed significant loosening.
>SBS is available in a range of nut sizes from M6 to M24, and bolt lengths from 20mm to 70mm. Standard materials high tensile steel according to DIN 17 240 as defined within DIN 267 part 13 and 316 stainless steel. Available finishes are zinc plating (standard) or nickel plating. IEC says specials are available on request.
