Sheffield-based Powertherm Contract Services Ltd (www.powerthermcontracts.co.uk
) makes thermal insulation jackets for the power generation and petrochemical industries; relying largely on a hand-crafted process due to the bespoke nature of the designs and the varied application of their products.
It purchased an Eastman CNC ply-cutting machine to automate some of its time-consuming processes - such as the manual cutting and marking of high temperature resistance glass fibre fabrics – but needed help optimising their use of the machine as it was only in operation two or three times a month due to not being fully incorporated into the company’s manufacturing process. The ply-cutter is now used daily following a project by the University of Sheffield Advanced Manufacturing Research Centre (AMRC) which looked at ways they could better integrate the kit into shop floor production.
Mike Taylor, Powertherm flexible insulation products division manager, said: “The decision was made to purchase this machine but the challenge for us was around how we integrated it into our production process. That’s what we wanted to push along so we got in touch with the AMRC whose research engineers produced a very thorough report that highlighted some of the problems we were up against.
“One of the recommendations in the report was to have a different design program that works better with the machine so we invested in the SolidWorks 3-D modelling program. Two of us have now been trained on that and we’re making progress. We were using a 2D program before and while there are similarities, the 3D programme goes much further in what it can do.
“It means we are using the ply-cutting machine a great deal more than we were and we have started setting up some user defined tables and inputting data for the different types of covers that we manufacture to create a library of designs. For us, the main benefits of this machine are around saving time and maintaining quality.
“We still cut things out by hand because we have nine sewing machines on the shop floor and for the cutting machine to keep churning out enough work to satisfy those nine machinists is quite a big task while we’re still trying to build up the design library. But once that library is full, it will contain thousands of designs and will be able to cut more.”
Mr Taylor said the work done by the AMRC was fundamental in giving the company ideas as to how it could progress: “I think that’s been the important thing we have got from the project. We knew in our minds that we needed to develop libraries of different drawings but we didn’t know how to go about doing that and the AMRC has given us the direction for doing that.”
Research engineers from the University of Sheffield AMRC’s Composite Centre visited Powertherm’s Handsworth factory to evaluate its current process for making glass fibre insulated jackets. They found that while this involves skilled operatives cutting fabric by hand, they largely work to paper drawings which means the company doesn’t have the digital drawings of designs required by the machine.
A number of recommendations were made by the AMRC team to help Powertherm better integrate the ply-cutter into day-to-day operations, including trialling the use of computer assisted design (CAD) tools to create a model able to generate digital product designs to be interpreted by the ply-cutter.
Calum Dickinson, research engineer at the AMRC Composite Centre, said: “In order to digitise the current design process to complement the use of the CNC ply cutter on the shopfloor, we suggested CAD methods could be used for flattening of 3D geometry to 2D patterns to streamline some of the simpler product designs.
“Once set up, that model would generate digital 2D line wire frame drawings which can be sent to the CNC ply cutter for it to then automatically cut out the required glass fabric shapes needed to construct the insulation jackets. We think this would be possible for about 30-40 per cent of what they currently manufacture and would definitely mean a reduction in production time.”
During the visit, Calum and the team found that the ‘made-to-measure’ nature of the jacket manufacture process posed a number of challenges when considering digitalising operations.
Mr Dickinson said: “The majority of the products designed and manufactured are one-off bespoke items, made-to-measure for a specific pipework installation. This means, at the moment, the glass fabrics are cut out by hand with operatives working to a job card and paper drawing of what they are supposed to be cutting out.
“The process works but it also means they can’t just jump straight onto the Eastman CNC ply-cutter and use it because they don’t have the digital drawings of these jacket designs which the machine requires. The objective for us was to understand what they were doing and come up with a set of recommendations on the next steps they could take.”
First, the team needed to understand the current design and production process.
Mr Dickinson continued: “There is one experienced designer, Mike Taylor, who figures everything out. He follows a set of rules and relationships from the measurements taken on-site which he uses to develop a jacket design and produces technical drawings by hand which are then sent to the shop-floor with a job card for skilled operatives to manufacture.
“The process is very labour intensive and because of the bespoke nature of the products, the design stage of the process is quite a large proportion as it’s done for every single product made. This factor, coupled with limited CAD experience within the company, means that potentially the time invested in making a CAD drawing of each part isn’t necessarily beneficial.”
To find a way forwards for the company, AMRC engineers and technicians with significant experience of automation in composite and technical textile manufacturing processes visited the factory on two separate days to carry out process timing trials.
A trial was set up to measure, mark and cut a 2m piece of fabric by hand, it took about 30 minutes. On the ply-cutter it was five minutes. However, the AMRC team found this wasn’t the same for all the different sizes of materials because for some pieces the operatives use templates which takes out the measuring step.
Mr Dickinson said: “For some parts, they will save time using the ply-cutter, particularly the bigger parts where it takes longer to measure if they haven’t got a template. They will definitely save time using the machine but it is hard to say precisely how much time because each of the products they make are different sizes.
“Another useful suggestion we made to them when using the ply-cutter was automatically nesting all designs onto fabric to make good use of the material. Nesting means rotating and positioning pieces to minimise scrap, typically resulting in 70 to 80 per cent material utilisation.
“The other saving by nesting is not just on the material. We saw that when Powertherm operatives are manually cutting out fabric, they save big ‘scrap’ pieces and store them in a box for later. When they have a pattern they think they can use the fabric for they take it out and measure it, and perhaps find it is not quite the right size so they put it back. That isn’t an efficient use of time. Nesting would help eliminate this.
“We have clearly seen areas where they can make changes and save on time, material and, ultimately, on cost.”
Alongside the AMRC report recommending the next steps, Mr Dickinson and the team hosted a workshop held to show Powertherm the next stages to explore once it has digital files for their fabric pieces.
He concluded: “They were really happy and I think they got a lot out of it. The workshop involved people from all aspects of the business: the finance officer, lead designer, shop floor operator and machine operator. We had a brainstorming session to talk about the machine and understand the process.
“That’s the beauty of working with an SME – you can get all those people in a room together and they all have knowledge about different aspects of the business, which helps us to help them. They were keen to set up that model and follow the recommendations we have made. It’s good to see some of that is now in place and taking shape.”