3D Design for Rapid Prototyping

Converging trio of technologies enables 3D design for rapid prototyping

Three-dimensional (3D) design is fast becoming an essential ingredient of the electronics design process – and especially so with the increased coupling of electronics and mechanical design. However, there have been major barriers to the adoption of 3D design in many fields, primarily the prohibitive costs of 3D solid modelling software – and also 3D printing – meaning that 3D design has largely been the preserve of specialist mechanical engineering departments within larger companies.

However, the confluence of free and easy-to-use 3D design software, the availability of component 3D CAD models and the increasing accessibility to 3D printing, has formed an enabling triumvirate of key constituents bringing 3D design capability within the reach of a much larger engineering universe. This evolution in 3D software and ‘additive-manufacturing’ technologies is allowing increasing numbers of engineers and companies to take advantage of the benefits offered by 3D design – particularly for the creation of quick-turn-around prototypes, which can potentially save months or even weeks in the product design and development cycle.


3D Design Software

The first of these three key elements is the 3D solid modelling software. Estimates vary, but there are millions of engineers worldwide that could benefit from the use of professional quality 3D design software. While traditional 3D design software has certainly been increasingly powerful, it can also be rather expensive. Licences for the latest highly sophisticated tools from the leading CAD vendors can cost anything from $5,000 to $30,000 and beyond, and also usually come with high-priced annual maintenance fees. A second impediment has been the significant learning curve sometimes associated with these tools: entry-level users may take many months before they become fully productive with an advanced 3D tool. Both of these factors are likely to have given pause for thought in many companies considering investment in 3D design. A common result has been the outsourcing of 3D design to specialist CAD companies, which can lead to bottlenecks in product development with the processing of even simple changes to a design taking many weeks.

While free or very low cost 3D design software packages have been available in the past, most have been fairly limited in their functionality. DesignSpark Mechanical is a new 3D solid modelling tool from RS that has the potential to change the situation. It is totally free-of-charge for engineers to download and use with no licence limitations. Developed in conjunction with SpaceClaim, the new DesignSpark tool is based on ‘direct modelling’ technology and enables users to create geometry easily with powerful and intuitive gesture-based modelling techniques. The availability of a free and fast-to-learn tool can offer significant advantages to industrial designers and electronics engineers, especially with the increasing integration and overlap of the worlds of electronics and mechanical design. It also means that others such as those working in sales, marketing and production can use this common platform to contribute and collaborate at the early stages of product and concept development before the creation of a physical model or prototype.

This type of tool can enable engineers to be more creative and will also support a more efficient product development process, allowing the production of professional concepts for RFQs (Request-for-Quotation) right through to delivering highly detailed and dimensioned manufacturing blueprints. And the tool can remove bottlenecks in the early design process by making amendments and additions rather than having to wait for the CAD department using advanced and sophisticated 3D design tools to rework a design. Importantly, DesignSpark Mechanical also exports designs in STL file format to enable rapid prototyping builds on 3D printers.


3D CAD Models

The second piece in the jigsaw is the availability of 3D component models. Engineers want to spend time differentiating their product rather than spending hours, days or weeks entering component dimensions before they can actually start designing and creating a concept. In addition, there is the human factor in creating these 3D models: errors can be made, which potentially could put back the design cycle by many weeks.

An extensive library of 3D models is therefore a highly valuable repository for an engineer. For example, the DesignSpark ModelSource library is an free online database of more than 38,000 2D and 3D CAD models covering key technologies including electronics, electromechanical, mechanical, pneumatics and automation and control. The 3D CAD models are also available in many proprietary file formats from leading CAD vendors.


3D Printing

The third element is 3D printing or additive manufacturing, which is creating many headlines these days in some extremely diverse applications. Various different technologies are being used by printers including Stereo Lithography (SLA), Electron Beam Melting (EBM), Laminated Object Manufacturing (LOM), along with Fused Disposition Modelling (FDM), which is probably the most common process used today in low-cost 3D printing machines. Although 3D printing machines are already being used as manufacturing tools to produce specific low-volume customised parts, perhaps the biggest advantage for many electronics companies is to use it in rapid prototyping. The technology has the capability to revolutionise product development – machine skills are not required to deliver prototypes, enabling huge time-to-market benefits as well as delivering a significant increase in design freedom.

3D printers are now becoming increasingly attractive with substantial reductions in price and some models now being priced at less than $2,500, making the technology affordable to a much greater range of companies and users. One extremely interesting development in the industry has been the RepRap project, which is an open-source self-replicating 3D printer initiative, in that the machine can make most of its own components. The RepRapPro 3D printers employ Fused Filament Fabrication (FFF)[1] technology, which uses a computer-controlled plastic-glue gun and a spool of plastic fed into a heated chamber. The plastic material is squirted out via a small nozzle to make the first layer on a baseplate, which is then lowered by a small amount ready for the second layer, and so on. An overview of the process used in the RepRap printers is shown in figure 1.

Figure 1 – RepRap 3D printer process, courtesy of reprap.org

The latest RepRap printer is the self-build Ormerod and is one of the most versatile 3D printers available today. Although the Ormerod is actually a monochrome 3D printer that has been configured to work with one type of plastic at a time – currently either compostable PLA or recyclable ABS filament, each of which have their advantages – the machine’s head is fundamentally designed to work with three-colour deposition. Key metrics of the Ormerod include a build volume of 200 x 200 x 200mm; build speed of 1800mm per minute and deposition rate of 33cm³ per hour. It offers a layer resolution of 0.0125mm, which is the resolution of how fine a step can be made by the machine’s motors; and an accuracy of 0.1mm, which is how accurately the machine can position things. The resolution is significantly finer than the accuracy, which is influenced by other factors such as the manufactured quality of the timing belt, for example.

A further range of low-cost 3D printing machines available are those from 3D Systems.  These products are fully assembled and are designed for the home, education and professional market. The range includes the Cube, Cube X and CubePro, and can deliver up to 3 colour print in 3 different materials: Nylon, PLA or ABS. They offer respective build volumes of 152x152x152mm and 273x273x241mm, and layer resolutions of 70 microns.


The Power of Three for Rapid Prototyping

In summary, freely available and professional-grade direct-modelling based 3D design tools such as DesignSpark Mechanical, in conjunction with free libraries of 2D and 3D component models, and increasingly high-performance yet low-cost 3D printers, now mean that 3D modelling and rapid prototyping are available to a much wider universe of users and not just CAD specialists within larger companies. This combination can truly empower electronics and mechanical engineers to embark upon end-to-end designs and significantly speed the concept development process.


[1] FFF is essentially equivalent to Fused Deposition Modelling (FDM)