Over the course of the last year, the aptly named Giga Coating GmbH has been building a brand-new, state-of-the-art coating facility, initially for HGV trailers, in Twist, Northern Germany. The new coating line is fully automated and can blast clean, coat, cathodic dip coat and powder-coat whole fabricated trailer chassis of up to 15.8m length, 2.7m width and 1.5m height – in all colours of the RAL rainbow (and more). 

Built on a 25,000m2 plot, the production area measures over 8500m2, 1300m2 of which are dedicated solely to shot blast operations. A Construction Blaster roller conveyor was supplied by Wheelabrator and is able to clean, descale and derust up to three million square meters per year. It is situated right next to the goods-in area for instant feed-in of the extra-large fabricated parts into the coating line. A labyrinth of roller conveyors ensures a constant flow of workpieces through the facility, including the blast machine. 

Blast power by the dozen

The giant “Type X“ roller conveyor wheel blast machine features 12 blast wheels with 15kW blast power each, accelerating abrasive onto the workpiece surface at up to 80m/s – that’s 285km/h. 

To ensure long maintenance intervals, maximum uptime and an increased service life, the inside of the blast chamber is clad with 10mm manganese steel plates. Inlet and outlet sluices of 4m length each and a series of rubber curtains reliably retain abrasive within the machine.

The workpieces enter the machine mounted on special skids, designed by the GIGA Coating team. Made from manganese steel to withstand the repeated harsh treatment inside the blast machine, the challenge when designing the skids was to ensure the blast treatment would reach every area of each chassis.

If the task is to create a homogenous surface roughness before coating (in this case Sa 2.5), all 12 blast wheels can be slowed down from 3000rpm to 1500rpm. All this and any other process parameters can be programmed into the machine, to tailor the blast process to the individual part.

Feeding the beast

For cleaning tasks, the blast machine is run at full power, achieving the high abrasive speeds mentioned above and consuming 220kg/min of abrasive per blast wheel – that’s over 2.6t/min. This high abrasive throughput is managed automatically via a clever reclaim and recycling system backed up by a 25t abrasive silo, equipped with fill sensors that automatically trigger top-ups. This means that there is always an optimum operating mixture of recycled and fresh abrasive available - for consistent, precision results. 

At a through-feed speed of 1-2m/min, the machine achieves cycle times of less than 15 minutes per workpiece. 

The state-of-the-art facility was commissioned in early summer 2018.