Advanced manufacturing system built around Festo components

Spirax Sarco is an excellent example of a UK manufacturing company competing on the global stage. To remain competitive and at the forefront of its market it invests heavily in automation. The latest project to come on-stream is a fully automated cell producing BP99 thermostatic capsules, which are precision high-reliability components used in many of the company's steam traps. The new line, which is based extensively on Festo automation equipment, is currently in the process of ramping-up production, and will shortly be switched in to replace the existing line completely.

Spirax Sarco undertook a strategic review of its capsule manufacturing capabilities, commissioning a number of feasibility studies and cost analyses. Having worked closely with Festo since the installation of the original line more than 22 years ago, Spirax Sarco knew the reliability it could expect. Over a 20-year period the old production line has more than satisfied the considerable demand for capsules. The vast majority of the Festo components are original and have not required replacement. During the evaluation process, the company used its relationship with Festo to ensure it was abreast of the latest automation technology.

Spirax Sarco briefly considered sub-contract manufacturing for its BP99 capsules, but quickly decided that this would not be viable due to the components' complexity. Given the unique nature of the capsules' design, the company also viewed the transfer of its core competency and intellectual property to the open market as potentially risky. Replacing like-for-like production equipment was judged not to be a good idea because it would not offer any scope for increasing throughput, and would severely compromise long-term manufacturing flexibility.

Decision to design in-house

The decision was therefore made to utilise the internal knowledge of the Spirax Sarco project engineers combined with external skills and resources from the Festo Customer Solutions team based in Northampton. Consequently, over the last two years, Roger Fern, Spirax Sarco's Production Engineer in charge of the project, has designed and developed the replacement line, calling upon Festo to supply him with 3D CAD models as soon as he had defined the movement profiles required by each manufacturing cell on the line. He found that this arrangement worked really well and says: "I found the Customer Solutions team, led by the Festo Project Manager, Ray Barnes, to be helpful in the extreme. It was often the case that I would simply send a few emails and maybe follow these up with a quick phone call, and then 10 to 15 minutes later I would receive the 3D model that I needed!"

In effect, Fern created a 'virtual' replacement line. Once approved, Festo then delivered the pre-assembled and tested handling modules for each cell, enabling a fully functional line to be implemented very quickly. Furthermore, the new line would accommodate Spirax Sarco's new 32bar BP99 capsules, whereas the existing line could only handle its earlier-generation 21bar models.

Under Fern's direction, Festo managed the specification of the system and controls – overseeing the mechanical build, including the complete system documentation and on-site installation and commissioning. The many control panels containing PLCs, operator interfaces and screens were programmed and commissioned on-site. Festo liaised with external suppliers to integrate the controls and complete the master documentation.

Acute need

The need for a replacement production line became more acute towards the end of 2005. The production equipment was effectively nearing the end of its service life – needing up to seven operators to maintain critical production target levels. Even more worryingly, the company was very aware that if obsolete equipment caused total line failure, it would impact heavily on customer service and sales.

The new production line was given the go-ahead at the beginning of 2005. It comprises 10 semi-autonomous manufacturing cells, linked by an SKF Flexlink conveyor system, with overall control handled by Allen Bradley PLCs. In all, there are 16 pick-and-place units, each of which makes extensive use of Festo's handling range and fieldbus valve terminals.

The new production line has cost in the region of £1million – less than half that of the alternative quotes obtained from complete line builders within the UK and mainland Europe. Spirax Sarco expects that its investment will be paid back within 3.5 years. The line is currently undergoing final testing and qualification; it has already produced 50,000 capsules, and looks set to exceed all expectations. According to Fern, "We are ironing-out a few minor bugs and confidently expect to achieve our production target very shortly, and then intend running the line four days a week, with Mondays set aside for component and line cleaning duties and routine preventative maintenance. The new line only requires one full-time and one part-time operator, freeing up at least four operators to work on other production tasks, and has already demonstrated that it can achieve our new target production rate."