July/August 2020

| FEATURES | www.smartmachinesandfactories.com July/August 2020 | 11 | I njection moulding is the linchpin of plastics manufacture. It has improved immeasurably over the years, with inventions including soluble forms of cellulose acetate, screw injection machines, gas-assisted injection moulding process, and an extensive range of material options. It has progressed from simple objects such as buttons and combs, to the complex products now seen in industries such as automotive, aerospace, healthcare, consumer products and packaging. At the other end of the scale, despite the industry’s dislike of its original name of Rapid Prototyping, 3D printing or additive manufacturing has struggled to evolve beyond a prototyping method, or at best a manufacturing option for small batches. Nevertheless, some design features, such as hollow infill patterns, are too complex for traditional methods and are exclusive to AM. It is also possible to include multiple materials into a single object, which allows different colours, textures and mechanical properties to be mixed and matched. Digital texturing enables complex, aesthetically pleasing parts within a single run without extra design and processing time. 3D printing has been given a sizeable boost by digital manufacturing: a part can be designed, manufactured in-house on a professional 3D printer, and tested, in a few days. The CAD-to-production speed makes it a perfect candidate for Low Rate Initial Production (LRIP), getting to market much faster, with the option to switch to the mass manufacturing processes when tooling is ready or when higher volumes are needed. After the initial investment to create the appropriate tools and moulds, injection moulding can be automated and the part rapidly mass- manufactured. This significantly decreases the amount of time needed per part. For any specific part, there is a crossover “breakeven” point of production volumes. It may be as few as 150 units manufactured, or more than 1000. At these lower production numbers, the cost of each injection moulded part can be 10 to 100 times as much as it would be using tool-less digital production. But by its nature, 3D printing is a layer-by layer process with a fixed time per part, meaning that the first component will always take the exact same amount of time to create as the last. To move the crossover point to the right, away from small batch production towards a genuine mass production option, suppliers are coming up with better and smarter 3D printing machines, but these are unlikely to eliminate traditional methods of manufacturing. Larger 3D printers are available, but these are expensive, and there is a trade-off between size and cycle time. Improving part quality also means 3D printing using laser-based systems at extremely high resolutions, which means the parts will take a lot longer to manufacture. A developing approach is digitalising not only the main 3D printing process, but also the activities happening around it. This underlines 3D Systems’ Figure4 Technology. Much like digital photography, digital printing and digital video, direct digital production has come about through a confluence of complementary technologies that have been intelligently choreographed for speed, accuracy and efficiency. Based on stereolithography, Figure4 Technology is a tool-less, easily scalable, AM process which is built around discrete and automated modules for each step of direct production. It is offered in three configurations that vary in footprint, capacity and versatility and uses a range of proprietary polymeric materials.  Standalone: a single build unit for ultra-fast and affordable same-day printing of prototypes and low volume production parts.  Modular: a scalable, semi- automated 3D manufacturing process that permits users to add more printer modules to grow capacity as the need to scale arises. Digitisation pushes the boundaries of additive manufacturing 3D printing (additive manufacturing, or AM) has hit the headlines with its role in producing emergency ventilator parts and supplies of PPE. But is it a serious competitor to established mass manufacturing methods? Andy Pye looks at how the boundaries are being extended.