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with movers and shakers

16th June 2017, UK

Rapid advances with additive manufacturing

Interview with Alissa Wild, manufacturing tooling lead, tooling solutions, Stratasys. © StratasysInterview with Alissa Wild, manufacturing tooling lead, tooling solutions, Stratasys.

Inside Composites: Can you provide a little background to the Stratasys story and the development of your additive manufacturing technology?

Alissa Wild: We are actually a company that started out of the kitchen of our founder S. Scott Crump about 25 years ago, developing the initial impetus for 3D printing based on fused deposition modelling (FDM) technology. Stratasys has grown to have just under 3,000 employees with 26 global offices and four manufacturing plants, with dual headquarters in Minnesota and Rehovot, Israel. To date, we’ve sold around 150,000 systems and have over 1,200 patents granted or pending globally. Our sales in 2016 were $672.5 million.

IC: Can you explain what FDM technology involves?

AW: Fused deposition modelling (FDM) is a thermal plastic extrusion based process. In this process you have a monofilament stock of thermoplastic which is melted and extruded layer by layer from the bottom to the top of the computer controlled tool paths.

Our other core technology is the Polyjet 3D printing system which works similarly to inkjet printing, but instead of ink onto paper, jets layers of curable liquid photopolymers on to a build platen. These can produce very fine feature details and very aesthetic prototyping parts.

The unique thing about Stratasys technologies is that we always employ a model material and a support material. All of our materials are paired very carefully so we can do complicated geometries and features using both materials.

Swift Engineering CAD Design on Screen & Part in Hand. © Stratasys

IC: What are your key markets for these technologies?

AW: We focus on the high requirement industries – aerospace, automotive, medical and dental solutions, as well as consumer products. We have very industry-specific applications and a product line that fits prototyping, tooling and production. We have made significant investments in the past two years to focus on a shift from just prototyping, pushing us towards manufacturing. With this, we have adapted our business model and the way we service our customers, investing in much more dedicated industry expertise inside the company. Our customers tend to start with prototyping and advance to tooling and manufacturing, so it’s a natural progression.

IC: So what are the benefits for general tooling applications in switching from a traditional machine tools shop to a Stratasys additive manufacturing system?

AW: Well, firstly, it will always shorten the set-up time. If you own your own printer or even use a service bureau you are able to get tools much more quickly. They print overnight and you can have them the next day. And the beauty of additive manufacturing is that complex geometries are not a challenge. We are not subtracting material, we’re starting from scratch and building from the bottom up.

The impressive mechanical properties of FDM Nylon 12CF allow engineers to explore the possible transition from traditional metal parts to 3D printed plastic composites. © Stratasys

In addition, there’s a great deal of design flexibility and the opportunity for parts consolidation. We’ve seen tools going down from 30 components to just one or two. The ergonomics of a tool can be improved, especially in terms of weight when switching to high performance plastic from metal.

And if you have multiple facilities all using the same tool, you can have one single file that everyone can print it from, allowing for guaranteed parts consolidation across the business.

IC: What are the key considerations specific to tooling for the composites industry?

AW: Our FDM systems enable capable, cost effective lay-up tooling to be produced in days, not months. They are compatible for autoclave curing at temperatures of 180°C and above and pressure of up to 7 Bar.

They also enable the production of robust, cost-effective sacrificial tooling for complex geometries which eliminates the complexity of traditional trapped tooling methods, with wash-out solutions capable at up to 120°C and break-away solutions at over 180°C.

Many parts of Utah Trikes’ products can be prototyped with Stratasys FDM Nylon 12CF, replacing metal and moulded plastics in a more rapid and efficient process. © Stratasys

IC: What are the key considerations in ensuring such tools meet usage requirements?

AW: The key considerations are the cure temperature and pressure coefficient of thermal expansion. The accuracy and tolerances have to be taken into account along with the design features and the build orientation. For vacuum bagging applications, the structural integrity has to be taken into account, as well as the surface preparation in respect of tool sealing.

IC: Do you have any case studies you can mention, to illustrate the benefits for composite manufacturers in practice?

AW: Well, for example, we recently supplied a multi-segment fairing tool for Aurora Flight Sciences in Virginia in just two weeks. They needed it in that time frame to hit their first flight target. It was for the production of a nine-foot long belly pod and a traditional tool manufacturer gave them a delivery time of between 8-16 weeks, so that didn’t work for them. The cost was also put at between $65-90,000.

The design of the tool segments with our technology allowed for a geometry allowing built-in “drop out” and easily removable parts.

This was a low temperature cure (100°C) involving no manual post-processing and could be quickly sealed with Teflon tape to meet the tight time requirement.

As a result, we were able to print their part for them and meet their deadline at a cost of $30,000.

Example of manufacturing tooling and production parts 3D printed using Stratasys FDM Nylon 12CF material. © Stratasys

IC: So that’s a saving of around 75% in terms of both lead time and cost?

AW: Yes, but even bigger gains are possible. In sacrificial tooling, for example, we recently worked with the advanced product development team of Swift Engineering, based in San Clemente, California, on the development of a smaller part, an aero inlet duct, around 1.5 metres long, with a complex, trapped tool geometry, taking it from concept design through to the actual tool fabrication in just a week.

This involved the use of a wash-out tooling material, our ST-130, in place of multi-piece bonded assembly and traditional wash-out tooling materials.

The FDM build time was actually less than 24 hours and involved a default porous triangle fill pattern which was optimized for autoclave curing and tool dissolution. The process was carried out at under 100°C and a 6 Bar cure cycle.

For this, the cost of using existing composite tooling with a weight of around 70kg would have been between $40-60,000 with a lead time of between 10-14 weeks. Using 9kg FDM tooling we took the cost down to just $2,500 with a build time of 40 hours. So that’s a 90% reduction of cost and time.

IC: So how would you summarise the advantages of your FDM composite tooling technology?

AW: It allows extremely disruptive cost and time savings for both high-temperature, autoclave cure-compatible solutions and those for robust, user-friendly sacrificial tooling solutions.

Medical device flexible tubing prototype 3D printed in Stratasys PolyJet Agilus30 material. © Stratasys

In addition, it’s ideal for effective, low cost ancillary tooling for machining, inspection and bonding fixtures, drill jigs, low-temperature masters etc. We back our technology up with comprehensive design guides to ensure complete success for our customers.

IC: Finally, you have just introduced your Nylon 12CF (carbon fibre) FDM material. What are its advantages?

AW: This is a carbon fibre-filled – 35% by weight chopped carbon fibre – thermoplastic material with the highest strength and stiffness-to-weight ratio available – close to that of aluminium.

Its stiffness and strength allow it to replace metal components in functional prototypes up to 140°C.

We think this is a great advancement. Stratasys made the decision to move into manufacturing, so as our customers came to us with higher requirements for tooling, this is our response. It will really challenge the perception of what plastic tooling can do.

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