WSP Textiles has replaced a Variator mechanical speed control device on its spinning machines with an ABB high efficiency motor and VSD. As well as achieving energy savings, the move has also completely eliminated the mechanical failures that once dogged WSP’s production operations. The company, based in Gloucestershire, manufactures cloth for billiard and snooker tables, as well as cloth for many well-known tennis ball brands such as Slazenger and Dunlop.
Critical to the manufacturing process are the spinning machines, which take wool slubbing and form it into a continuous yarn in readiness for further downstream processing. The problem with these machines was their speed control system. The motor ran at full power constantly, with the speed of the spinning machine controlled via a system of variable diameter pulleys (Variator).
As well as being inefficient, the system suffered a high number of mechanical failures and spare parts were increasingly difficult to find. Indeed, the company had to have certain parts specially made, which added to its costs. WSP's technical manager, Alan Harnden, takes up the story:
“We wanted to get rid of the variator system, as we were suffering breakdowns once a fortnight. This entailed a major strip down to get these pulleys out, taking two men up to one day. We were also losing a lot of production time. The spinning machines feed other machines downstream, which affected production volumes. As we are a 24/7 operation, these breakdowns were very disruptive.” Keen to replace the system with one that he could 'fit and forget, he set about researching VSDs as an alternative method of speed control. Mr Harnden again:
“Essentially we had two options - get VSDs or get a new spinning machine. These machines are very expensive, so buying a new one was not really viable. The ABB general purpose drive, ACS550, fitted into our old control panel and we could pick up the original signals. The VSD just slotted in, making it very easy and quick to connect up; other vendors’ products simply would not fit the panels we had. This would have required extra expense and time as new panels would take a week to fit, while the ABB drive was fitted in just two days.”
ABB authorised value provider, APDS - a local supplier for WSP was appointed by the textile manufacturer to help with the installation. APDS selected an ABB high-efficiency motor with an ACS550 IP21 drive, which WSP fitted itself, with commissioning support from APDS. Following this first project, three more machines have been converted to VSD operation, with WSP carrying out all commissioning.
There have been some energy savings, says Mr Harnden, but the biggest benefit for WSP has been the elimination of downtime from the moment the VSD was installed. "We have had no need to think about them and no spare parts are needed,” he adds.
The company is achieving better production quality as the ability to vary the speed allows them to adjust the tension of the yarn, giving a more controllable stop. This is gentler on the yarn and avoids the tangling that occurred with Variator control.
“VSDs have definitely come into their own and we would now fit them in place of a gearbox solution every time,” Mr Harnden concludes.