3D printing: Beyond the hype

Additive manufacturing is one if those technologies that gets engineers excited. The ability to print out different concepts somehow puts a smile of the face of most. Perhaps it makes the 3D CAD and design environment more real, more tactile, and brings dull 2D engineering drawings to life. Or perhaps it is just about indulging the inner geek in all of us. Who knows?

As the cost of additive manufacturing machines falls, more are seeking out the low-cost options, keen to explore what all the 3D printing hype is about. In fact the story is often the same. Weeks are wasted printing out Star Wars figures, Eiffel Towers and maybe the odd bit of design work, but then the novelty begins to wear off. When the office is strewn with small plastic paperweights and figurines at various stages of completion, you are forced to ask what has really been achieved. Now, low-cost small budget 3D printers have a place: for instance in schools to get students involved in design and engineering, in architecture, and maybe even for model builders. However, they are not going to replace traditionalmanufacturing methods and in an engineering design office they are in danger of being little more than a gimmick and distraction. Yes, you can show a 3D plastic representation to the sales and marketing teams so they can get started, but the finish and tolerance from most low-cost machines is going to do nothing to help their pitch. You get what you pay for Like many things in life, generally the more it costs, the better it is. With 3D printing this can mean a significant investment, so if you are serious about using it as a design and development process, clearly define just where and how you are going to use it. Seek advice from those that have the equipment and know what they are doing. One of the biggest uses of 3D printing has thus far been at the prototyping stage. Printing parts can allow different concepts to be passed around the room and also allow form and fit to be tested physically. Due to the better tolerance and finish of parts, it gives engineers confidence that what they have designed will be sized correctly and fit its intended use. However, advances in the process now mean that testing and pre-production checks can be carried out. Materials used in 3D printing processes can be made almost identical to production materials, as well as made from multiple materials in a single run. One company that has been able to exploit the potential of additive manufacturing to the extent that it now a acts as a 3D printing service provider, is East Midlands-based Rutland Plastics. "We were originally looking at the technology as we wanted to leverage what we were doing," says Stuart Lovett, marketing manager at Rutland Plastics. "As an injection moulder that also offers design and technical support, we were often being asked to produce prototypes. When we came across the Objet Connex, we thought we'd be able to offer functional prototypes as a bureau service as that might lead to some injection moulding work longer term. In fact, that is exactly what it has done." The art of prototyping is all about validating design, and this is where Rutland Plastics has found 3D printing to be very effective as a process. By printing out parts it can avoid 'redo's' during initial production runs and improve the quality of the serial production parts. Changes at the production stage of development, especially if the mould tool has already been made, can be extremely costly. This is only possible as the materials being printed are virtually identical to those that will be used during injection moulding. "Having a prototype in your hand has also helped to refine and simplify mould tools before," says Lovett. "That is something you do not always pick up on in CAD, as having a 3D image on a screen is very different to having something in your hand." And it is also about confidence and knowing what is going to actually be produced. When passing work to the manufacturing engineers, it gives confidence that it will be problem free and will not come back with a list of requested changes for production. Confidence is so important and although difficult to define, can add real time and money savings. "We were making parts for a pump," says Lovett. "It was a pump for draining central heating systems and they were uprating the motor. They were concerned about a part on the bottom of the pump that produced a filter-like effect so it takes water in. So if they made it at the size that would give them maximum flow, they were worried this would create a flow back. So they were thinking about only going half way because of the cost of modifying or having to re-machine the tool during production. So we printed prototypes of the two versions for them to test, and they were able to test these parts on an the actual pumps and prove they could use the maximum flow without any problems. "So it saved them compromising on the tool. They could not afford to go for the maximum flow on the pump and then have problems as there was no way back. So what they would have had to have gone half way and compromise performance." Plastic producer Solvay has also been able to boost its materials offerings by using 3D printing as a prototyping process to aid in the design and procurement of products and components. It has been particularly useful for the company as it enters new markets such as the automotive industry. "We are doing a lot of work in terms of confidence building by 3D prototyping," says Peter Browning, automotive market director at Solvay Engineering Plastics. "We can print out functional prototypes of the products. What is novel and innovative is not that you can print this stuff out, but that the material you are printing is the same materials as you use for serial production. So what you are getting is a functional prototype, so you can actually run application tests on it rather than just look at the thing." Solvay prints out in a polyamide 6, which is virtually the same material as you would use in an injection moulding process.?The biggest notable difference is the use of glass beads instead of glass fibre. Due to the nature of the process, the reinforcement is not quite as good – though it is close. "But the performance is correlatable with moulded materials," says Browning. "So you can put the pieces in an application test bed, see what happens, and have a very good idea of what the moulded piece will do and how it will perform." And it is also opening up unforeseen opportunities all the time. Lovett explains: "We use a lot of jigs and fixtures in the company for machining, and assembly, and these have traditionally been manufacturered out of wood or aluminium, which can be expensive and time consuming. And because it is multi-material, you can have the hard jig and then a soft surface on the ends, which was never easy with traditional manufacture. We are now printing jigs with the rubber surface on the contact areas so that it protects the part when it is being held. It saves us about 60% of cost. That is another area we are now exploring as offering as service to other companies."