Local steel major Allied Steelrode made history in 2015 with the purchase and commissioning of South Africa’s very first dedicated stretcher leveller. This machine was ordered from Red Bud Industries, the leading original equipment manufacturer (OEM) in the United States. The stretcher leveller, which has a length of 120 metres, is capable of processing material up to 12mm thick, 2 metres wide and up to 15 metres in length, fed from coils weighing up to 33 tons.
With this innovative machine in place at their stretcher leveller facility in Midvaal, Allied Steelrode was able to far more effectively produce stretched and flattened steel. Coil steel tends to retain various inherent stresses and latent memory as a result of the hot rolling manufacturing process. In this state, when subjected to subsequent processes such as laser cutting, water jetting, turret punching, welding and bending, these latent stresses cause the steel to distort and lift. This, in turn, raises the cost of fabrication as considerable re-work is involved to correct these variances.
“The speed and tight tolerances of modern fibre laser steel processors leave no allowance for metal lifting or distorting while it is being cut. De-stressed flat steel is therefore critically important in avoiding laser head crashes,” explains the Executive Director of Allied Steelrode, Warne Rippon.
While there have been other methods of destressing and flattening raw steel in use in South Africa, these are not as effective as Allied Steelrode’s stretcher leveller. “The effectiveness of our stretcher leveller process has been evidenced by the ever-increasing demand for our iconic trademarked brand, Allied Steelrode Stretcher Material (ASSM); which, since 2015, has been growing rapidly,” comments Rippon.
As ASSM has had the stresses eliminated and is perfectly flat, this allows fabricators and manufacturers – in a wide variety of industries – to produce superior products far more efficiently, at a lower cost. Part of this lowered cost includes a significantly reduced scrap rate. However, the stretcher levelling process does not change the mechanical properties of ASSM sheets, which comply with the standard of 0 to 1 International Units of Flatness.
“As the demand for our ASSM grew, we soon saw the need for a second, even more powerful stretcher leveller, which we also procured from Red Bud Industries. This became fully operational in July 2018,” explains Rippon’s partner in Allied Steelrode, CEO Arun Chadha.
The installation of the second stretcher leveller will allow for greater operational efficiencies, resulting in shorter lead times to delivery. This, in turn, allows our customers to improve their service offering and become more competitive emphasises Chadha.
The two stretcher levellers have varying capabilities which also represent a noteworthy value-add to customers. The first stretcher leveller is able to process steel gauges from 1.2mm to 12mm; while the second processes gauges from 3mm to 12mm. Having two operational stretcher levellers allows Allied Steelrode to be a more flexible supplier and also more responsive to the market, as the respective levellers can simultaneously be dedicated to processing different types of materials for more extended periods.
“What this means for us is that we have been able to drastically reduce the time lost in setting up when changing from one type of material to another,” explains Rippon.
For example, one stretcher leveller can be used to process steel which still has mill residue adhering to it; while the other processes stainless steel, which, in contrast, requires the line to be scrupulously clean.
“To physically stretch steel requires immense forces to be applied, which in turn requires a machine of some considerable scale,” comments Chadha. The new stretcher leveller weighs in at some 250 tons, and to accommodate this machine, the Midvaal facility needed to be expanded to a total of 15,000mÇ under roof.
