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Today digital data from a 3D model, produced predominantly using a CAD system, is exported to CAM software, which is used to convert that model into a file format that can be sent to a fabrication tool that will then produce a physical replica of that digital model. Fabrication tools are computer-controlled manufacturing processes and are either additive or subtractive. The additive process is 3D printing, which builds a product up by adding material layer-by-layer, whereas the subtractive process, which includes CNC machining and laser cutting, removes material from a solid block or sheet to create a product.
This workflow of turning digital data into physical objects is referred to as digital modelling and fabrication. Used as part of the prototyping process, its aim is to enable designers and engineers to evaluate the shape and function of a design before it goes into production.
Advent of 3D printing
Following the widespread availability of the personal computer and subsequently the accessibility of CAD, the next big revolution in this workflow was the advent of 3D printing technology. Mike Harvey, director of Bristol-based Amalgam Modelmaking, said: “I’d been in modelmaking for about nine or 10 years when the first 3D printer was shown in the 1980s on a television programme called Tomorrow’s World. Somewhere in the back of my mind I thought that this technology is going to put me out of work. But about 15 years later I was actually employing that machine to do work for me.”
Today Amalgam uses a variety of fabrication tools to create its life-size or scaled physical models and prototypes, and often more than one tool is used in a single project. “Recently we did a project that had a beautiful wood effect but actually used a combination of CNC, laser cutting and 3D printing to make it look like wood. It gave a crafted artisan feel which is still really valued by many of our clients,” said Harvey.
The accessibility of software and hardware tools within digital modelling and fabrication is a trend that has been growing in recent years. Not only has CAD and CAM software become more user-friendly and intuitive to use but so has the hardware with the widespread availability of increasingly cost-effective yet high-quality 3D printers. With the barriers to the technology lowering, it’s becoming easier for all users, rather than just those with specialist skills, to design and fabricate a product.
So while 3D printing has become a vital part of the product development process in evaluating designs intended to be mass produced by injection moulding, the technology is now also increasingly being used for the production of end-use parts. But it’s not a technology that will simply replace injection moulding, because as Dr Phil Reeves, who is the managing director of Reeves Insight and a leading consultant on additive manufacturing business strategy, explained the economics don’t add up as additive technology is still comparatively expensive. “Where AM offers the most benefit to users is for the production of low-volume, high-value and highly customised products,” he said.
Optimised solutions
Unlike designing for traditional manufacturing techniques, with 3D printing designers and engineers can take full advantage of the possibilities available in making a product or part layer-by-layer. However, the user does still need to understand the additive process in terms of the machine and material being used so as to best design for that process. This includes considerations such as 2D slicing, build angles, orientation, support structures and the surface finish required.
Additionally, now with the help of software tools such as topology optimisation and generative design, which are increasingly featured in many of the main CAD programs, as well as CFD and FEA simulation tools, users can take full advantage of the additive process and achieve optimised design solutions that are highly efficient, extremely strong yet lightweight.
For instance, HiETA Technologies, a Bristol-based product development company specialising in metal AM, has produced end-use parts that exploit the benefits of AM. Taking its high-temperature compact heat exchangers (up to 800°C) as an example, it features a weight and package reduction of up to five times that of conventional products and is produced in corrosion-resistant materials.
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Content published by Professional Engineering does not necessarily represent the views of the Institution of Mechanical Engineers.