Modelling and Prototyping Aims: To be able to DESCRIBE the process of SKETCH MODELLING and BLOCK MODELLING. To be able to EXPLAIN the reasons for using rapid prototyping in the development of graphic products To be able to DESCRIBE the advantages of using virtual modelling/ virtual ‘walk through’

Communicating with models Sketch models can be used to explore ideas These models are sometimes called concept models They are usually made quickly using easily worked material such as card, polystyrene or clay By making a very simple model you can quickly see weather your design Looks right Is it the right size and proportions Do the colours work These can easily be tried and changed if necessary. Designers often use sketch models at the initial design presentation, together with the design layout. They help the customer to understand the ideas being proposed

Block Models Usually the next step in modelling More accurate than a sketch model Outward appearance must be exactly as the finished product would be Made from a solid block of material with no internal details or moving parts Block model allows you to see all external details of the design, including colour, texture screws and joints. It must be as faithful a representation of your design as possible. Time, patience planning and attention to detail are needed to build a successful block model Making changes to block models is tricky, extra time spent at the sketch stage, finalising choices will save wasting time In industry accurate models are used, not only to evaluate the design, but also for photographs for advertisements and brochures before the final product is ready

MDF can also be used for the production of moulds for vacuum forming: For example, to produce the transparent ‘blister’ in blister packaging. A mould can be cut and shaped to create interesting shapes in much the same way as producing a product model. MDF is the most suitable wood because it has no grain, so the mould will not leave an imprint on the vacuum-formed plastic shape. It is important that the completed mould is very smooth, has slightly angled sides (usually 5 degrees) and rounded or ‘radiused’ corners and edges. This will ensure that the mould can be easily removed once vacuum formed. BLOCK MODELLING of MDF The most important role that medium density fibreboard (MDF) has to play in a graphic product is in the manufacture of three-dimensional (3D) models and moulds for vacuum forming. MDF is an ideal material for producing a high-quality model because it: can be cut and shaped easily with a range of hand tools, as it has no grain has an excellent surface finish when sanded smooth ~ can be spray-painted, once sealed, to achieve a high- quality, professional finish.

Rapid prototyping using stereolithography Stereolithography involves the creation of 3D objects using laser technology to solidify liquid polymers or resins. Specialist software applications can be downloaded onto a stereolithography machine, so that 2D CAD drawings can be converted into 3D models. The process is based on the computer ‘slicing’ the virtual 3D object into hundreds of very thin layers (typically mm thick) and transferring the data from each layer to the laser. The laser draws the first layer of the shape onto the surface of the resin, causing it to solidify. This layer is supported on a platform that moves down, enabling the next layer to be drawn. This process of drawing, solidifying and moving down quickly builds the shape up, one layer on top of another, until the final 3D model is achieved. Stereolithography prototypes are often delivered within three to five days of receiving the client’s data, so this process saves both time and development costs. So far only a few companies have this technology

Rapid prototyping using CAD/CAM Stereolithography Manufacturing needs to reduce time and costs in developing a new product

Advantages of using RPT in the development of products: Fast entry to market due to a reduction in lead time (the time between the initial design ideas and the actual product being sold) Reduced development time, which saves money Produces complex, intricate shapes accurately directly from CAD data Accurate testing of models as materials are more representative of the final product: for example, this process produces an actual polystyrene casing rather than a MDF or StyrofoamTM block model of one. Two RPT processes commonly used by manufacturing industries are stereo lithography (SLA) and 3D printing (3DP).

3D printing 3D printing gives designers and product development teams rapid prototyping technology in the office, so that they can produce 3D models in minutes. 3D printers have become financially accessible to small and medium-sized businesses, including some schools, taking prototyping out of heavy industry and into the office environment. CAD software sends the 3D image to the 3D printer and the item is ‘printed’ layer by layer in a range of materials. Concept models can be produced quickly and with working parts using a desktop-size 3D printer. 3D printers offer speed, low cost and ease of use, which makes them suitable for visualizing designs during the development stage of the design process.

Like stereolithography, 3D printing works by converting a 3D CAD tile into thin cross- sections. This information is then sent to the 3D printer, which starts to deposit material layer by layer, creating a 3D object. One variation of 3D printing involves an inkjet printing system. Layers of a fine powder are bonded by ‘printing’ an adhesive from the inkjet printhead in the shape of each layer, as sliced up by the CAD file. This system allows the printing of full-colour prototypes and is also a fast method of producing a complex prototype.

Visual Modelling TASK: Virtual tours by architects when showing a client a new building or interior is important before construction starts. **Can you think of and write down as many advantages of this as possible ** Product design teams can significantly decrease the time taken to design and develop a new product with 3D modelling, saving development costs and reducing time to market. ‘Virtual products’ can be tested and evaluated without actually bring manufactured