2005-10-04 - ABB Drives Alliance partner Slater Drive Systems (SDS) has saved a metal pressing company £18,000 on the cost of new drives for two of its presses.
Unipres of Washington, Tyne and Wear, which produces pressed metal components for automotive industry, needed to replace the DC drives on two of its large blanking presses as they were becoming unreliable and were difficult to repair.
The difficulties were leading to downtime that the company, which bases its production on just-in-time manufacturing, could ill afford.
Unipres made enquiries with the press manufacturer, which suggested using regenerative AC drives. However, when SDS analysed the company’s needs, it decided that this type of drive was not needed, as the light duty environment of the press shop would allow the use of standard brake chopper drives.
“The presses work off a flywheel and once the wheel is up to speed, the drive simply needs to keep it there. Consequently, there is little need for regenerative braking, says Ian Holt, production engineer for Unipres. “SDS told us that the small energy savings to be gained by using regenerative drives in this application were not enough to justify the extra cost.”
The drives chosen were two ABB standard drives feeding 132kW 4 pole AC motors. The total cost of these drives was around £18,000 less than the alternative regenerative drives.
As well as the supply of the equipment, the £70,000 contract also included new control panels, all replacement cabling and mechanical modifications as well as interfacing and interconnection with the existing control system and commissioning.
Installation and commissioning were completed in only two weeks.
This provided quite a challenge for the SDS team. “We wouldn’t normally undertake two such major swap outs in two weeks, “ says Stuart Combe of SDS, “but through careful planning, the first one went smoothly and so we knew we could do the other.”
The presses involved were a 400 tonne blanker press and a 1200 tonne transfer press. Initially, the intention was to modify the 1200 tonne transfer press during the two week summer shut down. However, Unipres decided to go ahead with the modification of the 400 tonne blanker in addition to the 1200 tonne transfer press during the same two week period.
Installation of the drives proved a challenge, due to the unusual location of the control equipment, which is mounted on a high level gantry with limited space. To overcome these restrictions, it was decided to extend the gantry to accommodate the new panels and run supply cables from the old ones to feed them.
The company already had some ABB equipment on site supplied by SDS. Combe says: “Unipres were pleased with the service from SDS and with the ABB drives and so decided to ask us to install the new AC drives on the presses.”
Ian Holt says: “We already had ABB drives on some equipment so it was logical choice for us to go with them. The new drives and motors have reduced our downtime and cut our maintenance. We have had no trouble with them since installation. Also, if anything does go wrong, because the drives are based on individual cards, it is easy for Slater Drives to come along with their spares suitcase and just slot a new one in. The ABB drives and motors are ideal for our needs.”
Since the installation, Unipres has placed a further order with SDS for two more press upgrades, using the same ABB motors and variable speed drives.