Hoogovens' aluminium standing-seam roofing sheets, available in effective widths of 300, 305, 333 and 400mm, are generally roll-formed in the company's factory in Haydock, Merseyside. This method is suitable for most applications and facilities are available for mitring and re-welding sheets to produce a cranked unit, or multi-curving a sheet (the current record stands at seven curvatures to a single sheet).
But in certain circumstances - for example, where site access is difficult for the delivery and installation of large, deep-curved units, or where exceptionally long lengths of sheeting are specified - an alternative exists in on-site roll-forming, either at ground or roof level. In the case of the latter, the fully-integrated production facility (roughly the size of a sea-going container, 12m long) needs to be mounted on scaffolding or other type of platform, so that when aluminium coil is fed in at one end, finished kal-zipregistered comes out of the other, ready for installation.
Almost infinitely variable lengths are possible: 45m in the case of the new automated processing centre for the Royal Mail at Wolverhampton, 65m at a new warehouse in Avonmouth for Matthew Clarke.
How it's done
Once on-site roll-forming is the chosen option for a particular project, Hoogovens' professional team produces a full operations document, detailing requirements, safe working procedures and risk assessment. It then decides on the siting of the mobile unit, security for storage of the aluminium coils, how they will be moved, and the means by which the manufactured sheets can be safely handled manually and lifted into final position.
The trailerised roll-former is delivered to site by tractor unit. It is then positioned either at ground level on hard-standing, or hoisted on to a pre-prepared scaffolding or platform to eaves level. Site layout and installation requirements will determine which is chosen. The experienced team can deal with most eventualities, but in the case of a major technical problem, engineers are available to sort them out and minimise down-time.
Before the unit leaves the factory, the profile gauge and guillotine are pre-set and then can be re-set on site if a second run, to a different specification, is required.
Once in position for ground-level production, the trailer is levelled and the run-outs are off-loaded with the on-board crane, and then positioned according to the length of the run. For use at eaves level, all the equipment (including run-outs and generator) must be hoisted into position by an on-site crane. Then the generator is started, the lubricant levels are checked, the decoiler lowered and levelled and a coil is brought from the store to commence production. Verbal warnings are issued prior to the process.
A secure compound will be required to store the number of coils needed for the job, and a skip should be made available for discarded materials and coil ends. The valuable scrap can be recycled into building sheets.
Coil, weighing from two to six tonnes, is transported to the roll-former. It is then loaded on to the unit either by on-board crane (for ground- level production) or by site crane (for roof-level manufacture). Once loaded, the coil is fed manually into the roll-former and inched forward ready for a short test run to check profile and tolerances. The total set-up procedure takes only a couple of hours, depending on conditions.
60m runs every 90 seconds
If the required sheet length is about 60m, it will only take about 90 seconds to produce each run of kal-zipregistered. It is also possible to reposition the mobile roll-former during the manufacturing process, so that the finished sheets are as close as possible to where they will be required. Hoogovens can also supply a lifting beam, 60m long, to carry the sheets into position.
kal-zipregistered produced in this way is indistinguishable from that which is factory-made and achieves the same performance, and one of its first mobile roll-formers is well on its way to completing 200,000m2 of sheeting.
As for the future, Hoogovens is currently looking into the feasibility of producing sheets 120m long - almost twice the longest so far - with a natural curve.