High Torque Fastener Systems
The enemy of mechanic fasteners is vibration. Loosening can be infuriating and at the extreme, hazardous. In terms of the user such events are seen as poor design and many other reasons that could have contributed to the failure are also blamed. Whilst the variations of bolted joints are prolific, so are the types of assemblies!
Sheet metal fasteners have been specified in considerable applications for a number of years and have proven to be acceptable in numerous industries. The resistance to vibration can be variable by application and over time loosening may occur. Some industry statistics have shown that up to 37% of applications fail due to thread striping problems, thus requiring rework and refurbishment plus the inevitable variable costs of down time and re-assembly.
The High Torque Fastener System can overcome the problems of thread striping in several material types and is flexible for design engineers to use in a variety of applications when constructing sheet metal panels or enclosures.
The Principals of the High Torque Fastener System.
The High Torque Fastener system is designed to accommodate a large range of sheet material gauge thickness. Taking into account these various material combinations, the system has an advantage over conventional sheet metal screws, which are not specifically designed to accept multiple gauge material thickness’, as well as the relevant overall stack thickness within the joint.
An added premium with the High Torque system is the anti-vibration properties that are integral within the design. The formed sheet materials when clamped endeavour to return to their original position. This has the effect of reducing the possibility of the screw disengaging, unlike a conventional cut or formed thread which requires the possible addition of shake proof washers or applied patch technology to the fastener in order to resist loosening.
The High Torque Fastener System is designed to achieve the maximum engagement of the buttress screw thread into the pre-formed sheet material anchor threaded hole of the sheet metal panel. The thread-formed helix acts as a natural lead in for the screw, eliminating any cross-threading and allowing acute angles of pressure to be applied during assembly.
The Fastening System Attributes.
The intricate feature of the system is one of addressing the efficiency of the clamped joint. To achieve this, the natural pliability of the mating materials inherently secures the loading on the joint, endorsed by the buttress screw thread.
The rigidity aspects of the system culminate in diminishing the likelihood of loosening due to the perfected thread engagement in combination with utilising the engineered strength within the joint itself and the materials being clamped.
Material thickness and thread lengths are important design ingredients that have a relationship to thread diameter and the depth of the joint. The inherent energy within the fastened joint provides a consolidated fixture, which can successfully resist most fatigue assaults.
The drive media and fastener head types conform to international standards and a suitable range will meet the requirements of the designer.
The Major Benefits
This Case Study emphasises the on-going innovation within the fastener community; there are always new ways to increase fastener and fixing efficiency and achieve cost savings.
Submitted by Christopher Payne – Materials Engineer High Torque Fastener Systems Ltd.
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