Finding a new path for composite toolmaking

Two UK companies are taking an innovative approach to composite toolmaking – by tackling it in a non-traditional way. Lou Reade reports.

Toolmaking is a long-established process that has many rules, regulations and traditions. However, these traditional methods are not always appropriate in the modern world: customers are increasingly demanding shorter lead-times, or lower prices, or more complex designs – sometimes, all at the same time.

These demands cannot be satisfied using traditional methods, so toolmakers will need to embrace emerging technologies – such as 3D printing – in order to compete. Here, two UK tooling experts reveal how they have embraced modern technology to change the way that composite tooling is designed and built.

Dashing ahead

Tim Robathan is a design engineer with a background in the F1 industry. In the early 2000s, he found he was designing ever-more complex composite parts.

“I might spend weeks thinking how to use a 5-axis CNC machine to make a particular tool,” he says.

While 3D printing was quite new at the time, Robathan thought it could be applied to toolmaking – to make designers’ jobs easier. Despite early objections about ‘plastic tools’ that might not be thermally stable or accurate enough, the industry has since embraced their use – and Robathan’s company, Dash-CAE, has become a specialist in producing composite moulds using 3D printing.

The process uses fused deposition modelling (FDM), which Robathan says is less complex than other 3D printing methods – and less expensive. At the same time, it deals only with thermoplastics – which have “dependable, reliable properties”. The downside, he admits, is that it struggles with surface finishes – though he says people are now more accepting of this.

The company recently bought a large FDM system – a Stratasys F900 – with a print volume of a cubic metre. This comes in response to customer demands for larger moulds. With its existing Stratasys 400 (whose print volume is 400mm cubed), Dash-CAE was producing mould ‘parts’ and gluing them together.

“Of course, as soon as we bought the new machine, we were asked to make even larger moulds,” he says.

The machine was recently used to print a tool in four parts that were subsequently glued together. While it may sound like a compromise, he says this approach has advantages. For a start, the gluing process can help stiffen the mould – and is easier than adding stiffening ribs to the design. Overall, this can lower the cost of making the mould.

Going back to thermoplastics, Dash-CAE tends to use Ultem polyetherimide (PEI) as it has the necessary properties to compete with some of the materials that are traditionally used to make composite moulds.

“We use it because it suits the composite parts that we make,” Robathan explains. “Our moulds need to work at high temperatures and pressures – which is not true of all composite moulds.”

He says that PEI tooling is still a bit of a ‘secret’ – and could find wide use within the industry as an alternative not just to low-grade alloys but also to carbon tools.

“A 3D-printed Ultem tool will need some finishing – but it can be completed within a week. That’s a hard thing for procurement departments to ignore.”

An Ultem tool can compete with a carbon tool in terms of the number of parts it can make but not in terms of part accuracy – though it is still possible to overcome this,” he says.

“It’s about designing your part to ensure that the tolerances are not horrendous.”

While similar high-end Stratasys machines exist in the UK, he says they are all likely to be owned by large engineering companies – for their own exclusive use.

“Ours is open to all,” says Robathan.

Full automation

Martin Oughton, managing director of Mouldbox, has a similar forward-looking attitude, and was also frustrated by the traditions of toolmaking.

“The whole process is still very manual,” he begins. “Technology is available – but is not used very efficiently.”

To this end, Mouldbox has created an online platform that automates the entire process of commissioning composite tools – which includes their design, pricing and fast manufacture.

At its heart is a machine-learning algorithm that can determine the manufacturability of a part – from a CAD file – then design a tool for it, produce a quote and confirm a lead-time.

“You can upload a CAD file to our system, and get a free quote within minutes,” he says.

Determining manufacturability helps to create a precise quote. For instance, working out how many moulds a part requires will feed into the final price.

For the manufacturing side, Mouldbox has built up a network of partners – small machine shops mainly in Europe and North America – who between them own more than 100 5-axis CNC machines. The sites have all been audited by Mouldbox for quality, and their ownership of 5-axis machines is vital, he says.

“We’re about complex manufacturing – and could not sell any moulds without 5-axis production,” he says.

In future, Oughton plans to extend the partner network to machine shops in lower cost economies, including Brazil, India and South Korea. This would allow Mouldbox to deliver on the next part of its plan: balancing cost against lead-time.

“Right now, we offer a standard quote with a standard fast delivery time,” he adds. “Later this year, we plan to introduce the ability to offset price against lead time.”

Here, he says, a customer that requires a large mould may prefer a lower price to fast delivery. He sees it working a bit like a flight-booking website – with lower prices for less urgent requirements.

Another plan for the future is to help its supplier network automate the toolpath file – by supplying a G-code that would theoretically allow them to ‘press and print’ a tool.

“We want to make composite tooling manufacture as easy as 3D printing,” Oughton concludes.

The toolmaking industry may still be very tradition-dominated, but disruptive technologies like those from Dash-CAE and Mouldbox can help to reduce both prices and lead-times for complex composite tools – which can only be of benefit to manufacturers.

www.dash-cae.co.uk

www.mouldbox.com