Southwood Export Limited (SWEL), a New Zealand company, has been operating since 1985 and is a leader in processing of plantation timber. SWEL had increasingly been experiencing problems with metal contamination at their Bluff chipping plant, with bullets, metal stakes, barbed wire, bolts and more embedded in the wood. Supplying export pulp and paper markets, SWEL could not afford to have metal contamination in their product.
After a major incident SWEL realised it needed to act quickly. After approaching a number of vendors SWEL selected a Sesotec DLS metal detection solution from Reynolds Group. SWEL needed to detect metal fragments down to the size of a 10 cent coin, with the wood chip 350mm deep moving on the conveyor at 190 metres per minute, in the open air, 8 metres above the ground. With a constantly variable climate, that can range from high heat and direct sunshine through to sub-zero blasts direct from Antarctica, it was clear no ordinary metal detector would do the job, which is why the Sesotec DLS was selected.
Plant Manager Ross Best, who has worked with a lot of metal detection systems, says he selected the DLS both for its strong design features, and for the support capability of Reynolds Group. “It was a bit more expensive than some other products on the market but not out of touch. I like the IP rating, stainless design, 360 degree detection and the repeatability of detection. I also found the staff on board very approachable and easy to deal with”, said Ross.
Given the installation at height, the ability to disassemble and then reassemble the DLS around the existing conveyor without any cut-in or modifications was a big selling point. The IP67 rating, solid stainless steel construction, and advanced signal processing to deal with the fluctuating environment meant the DLS was one of the few units up to the task.
Ross has been very pleased with the performance of the DLS, “The unit we purchased has been a very reliable unit compared to others I have experienced in the timber industry. Once tuned it has very few trips where we do not find anything and works well at any tonnage rate or timber moisture content and because of the 360 degree detection it doesn’t matter where the contamination is in the product.”