Traditional fencing systems incorporating wood products or steel fencing systems such as chain link, twisted hexagonal fencing and steel palisade have inherent weaknesses and can be easily overcome.
The increase in political and socio economic security concerns has hailed a subtle change in the viewpoints of many governments who have moved from embracing open policies with other countries towards a more protectionist stand point. The myriad of recent events such as the refugee concerns in Europe, the mooting of a border wall between the USA and Mexico, wars and political instability in many parts of the world and simple criminal activity has given rise to an increasing requirement for superior, top-quality fencing to protect borders, premises and assets. Traditional fencing systems incorporating wood products or steel fencing systems such as chain link, twisted hexagonal fencing and steel palisade have inherent weaknesses and can be easily overcome. Concrete solutions become cumbersome, expensive and time consuming to erect and despite this, still do not offer adequate protection.
An analysis of the different solutions is well documented in “The Assault Experiment” which can be found at https://www. youtube.com/watch?v=jROZcYVuNno and after considering the different available options it becomes immediately apparent that the best solution to security fencing requirements is welded mesh fencing.
Typical aspects of welded mesh fencing include horizontal wires that are very closely pitched (normally around 12.5 mm) which has the effect of making it difficult for any wire cutting device to get in between the wires as well as limiting the ability for a human to gain purchase on the wire in order to scale over the top of the fence. While a simple welded mesh security fence product already offers significant strength benefits over other solutions, available options such as double horizontal wire systems, double skin systems and alternating horizontal under/over horizontal wire systems offer increased strength and security features as well as appealing architectural finishes.
With the development of any new product, there arises the challenge to manufacture that product in the most efficient, cost effective way while still ensuring the quality of the product. Quality and consistency for security meshes, due to the very nature of the application, require careful consideration of manufacturing techniques to ensure a fail-safe and consistent product.
The qualitative parameters of welded mesh fencing typically incorporate the following requirements:
- Average weld shear strength may not be lower than 75% of the tensile strength of the wire. No single weld under 50%.
- Flatness of mesh panel when the panel is laid on a flat surface, then the maximum lift of any part of the panel cannot be more than 40 mm.
- Tolerance on measurements between wires (wire pitches) being less than +/- 0.5mm and overhangs of the wires around the outside of the panel measuring 0 mm +/- 0.1mm!
- Diagonal accuracy of less than 0.1% of the diagonal distance of the panel.
While other parameters exist to ensure the strength, aesthetic properties and ensuring simple and trouble free installation of the mesh panels, the above parameters represent a significant challenge for the manufacturers of welded security fencing. The reason for this is that the resistance welding process, by its very process, heats up the wires to be welded. With the wires being very close together the welding density is very high. This coupled with the requirement to weld the wires at high speed means that there is little time allowed for cooling of the welded intersections and the welded panel becomes very hot, to the point that it is too hot for direct handling by human hands without protection immediately after the panel has been completed. The resultant expansion of the material during the welding process and contraction once the welded panel cools results in warping of the panel and weakening of the weld intersections resulting in a poor quality product which is unable to meet the aforementioned qualitative requirements.
This problem has been the challenge that manufacturers of resistance welding machines have had to face.With this continual need to push for innovation, Clifford Machines & Technology has recently designed, manufactured and successfully commissioned two new wire mesh fencing machines, for a major international supplier of welded mesh fencing products which boast unique features allowing the customer to produce an entirely new and unique range of weldmesh fencing. These wire fence machines boast product flexibility, reliability and quality without compromising speed of production.
To produce welded wire products that meet production demands is a feat in itself, but Clifford, using advancements in the crosswire pre-tensioning system, have a multi-height tensioning system to allow tensioning to take place at different heights. This system coupled with Clifford’s direct welding heads has made it possible to produce perfectly flat welded wire mesh while still maintaining the stream of production, allowing both quality and production targets to be met efficiently. These particular welded wire fencing machines have numerous advances but one in particular is production of fencing with of both over and under cross wires. This in itself is not a particularly new technology but Clifford has also made it possible with different wire diameters and with under and over cross wires at different pitches to each other which can also be flush trimmed to the outside line wires – truly a world first. This allows the client flexibility to produce various products, with minimal setup changes. The ability to quickly change between products makes these machines as flexible and versatile as the ever changing wire industry market place.
There is always a fine balance that every industrialist faces between product quality on one side, and production speed on the other. Clifford’s advancements have created a synergy between both quality and production speeds.