Prototype Techniques

Prototype tools, where small quantities (perhaps of 50-100 moldings) are needed for test and evaluation, can be made of materials such as mild steel, aluminum, or epoxy resin tooling compounds. The tool Ufe is limited and there is no long-term alternative to having a correct production tool manufactured. 

Specialists, such as the UK Warwick Manufacturing Group and the German Fraunhofer Institute for Production Technology and Automation, identify three areas where rapid prototyping is now paying off  

Polyurethane board can include a low density foam block for applications from styling models to cutter path verification, and styling. Low density master models from which vacuum-consolidated RP tools and components can be produced. 

LSL has also developed Magnum Ceramics Composites, allowing it to mill a plug or master mold and spray up a production tool with ceramic 

Vacuum castings, the more basic processes, such as vacuum casting in silicone molds, also have their place and a range of gun-applied TS polyurethane resins introduced by Axson, France, avoids the need even for the casting machine. Martello Design has developed a polyurethane injection process, Thin-RIM, complementary to its existing vacuum casting method, which allows features and wall sections down to 0.5 mm to be produced. 

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A prototype is a 3-D model suitable for use in the preliminary testing and evaluation of a product (also used for modeling a die, mold and other tool). It provides a means to evaluate the product s performances before going into production. The ideal situation is for the prototype to be the actual product made in production. However machining stock material and using rapid prototype techniques can make prototypes (Chapter 4, BOOK SHELVES). 

Harrison C, Cabral J, Stafford CM, Karim A, Amis EJ (2004) A rapid prototyping technique for the fabrication of solvent-resistant structures. J Micromech Microeng 14 153-158... 

Cyclohexyl phenyl ketone was used by Johnson et al. (3) to photocure intermediates for three-dimensional articles using rapid prototyping techniques. The product exhibited stable tensile properties over time. 

Derived from standard desktop printers, drop-on-demand techniques, such as electrohydrodynamic jet (e-jet) printing, solid freeform fabrication (SFF), or piezoelectric inkjet printing, are among a few notable examples of rapid prototyping techniques that have been developed to pattern biomaterials. With the incorporation of a user friendly computer interface, these techniques have been employed to process a number of multiplexed, biomaterial constructs without the use of masks, stamps, or any other time consuming processing equipment. The design of such constructs with minimal feature sizes in the microliter to picoliter resolution has been demonstrated and will be discussed below. 

There are many classifications of rapid-prototyping techniques, but perhaps the simplest is the broad classification into liquid-based and solid-based techniques. Liquid-based techniques are focussed on systems that are initially in the liquid state and are controllably cured into a final product shape. Solid-based techniques involve an initial solid preform or powdered sample that is melted, fused or sintered together into a final product. 

Since this book is focussed on chemorheological processes, we will focus on rapid prototyping and manufacturing processes that include reactive processing (mther than the rapid-prototyping techniques involving only physical transformations, i.e. sintering of metals, ceramics or thermoplastics). 

Similar to other rapid prototyping techniques, ACR s EFF process begins with a 3D drawing (AutoCAD,. DXF, etc...) of the component to be fabricated. The file is imported into ACR proprietary software and sliced into the individual layers and fill patterns which will be utilized to build the part. The fill pattern in each successive layer ultimately becomes an extrusion path for the EFF machine to follow while extruding the chosen material in the shape of the component being fabricated. 

Pioneered first use of recent computer aided manufacture (CAM) prototyping techniques for tank manufacture employing XLS, VBA, TCW, DWG, and STL computer languages Developer wider, more fundamental flavor of analyses applicable to new systems (including hydrogen infrastructures), as well as motor vehicles... 

Near-net-shape processes for prototyping and smaU-batch production by means of rapid prototyping techniques can be characterised by the process chains listed in Figure 28. 

In principle, prototypes or patterns that in turn enable the manufacture of prototypes and small batches in combination with casting processes can be produced directly by means of rapid prototyping techniques. Rapid prototyping can also be applied to manufacturing primary shaping and forming tools to be used for the fabrication of prototypes. 

The choice of prototype technique is best determined by assessing what properties of the product are unknown at the time. What is of greatest interest stiffness, yield load, or heat distortion temperature This will help to determine the simplest and least expensive prototyping technique. Techniques for creation of a physical prototype product include the following ... 

Medical modelling the application of advanced design and rapid prototyping techniques in medicine Second Edition... 

Table 2.3 Description of rapid prototyping techniques [203, Linxe, 2002]...

Fig. 79 Principle of model generation by rapid prototyping techniques...

Chang-Yen DA, Gale BK (2003) An integrated optical oxygen sensor fabricated using rapid-prototyping techniques. Lab Chip 3 297-301... 

Cranial defects can be caused by injury, infection, or tumor invasion. Large defects should be restructured to protect the brain by using cranial implants. The conventional method is to cover the defect with bone cement. Nowadays, custom-made implants designed for the individual patient are available. Rapid prototyping techniques and medical-grade plastics allow surgeons to repair large holes in skulls. 

It would be desirable to manufacture lightweight articles from particles made from aluminum or magnesium or their alloys using the 3D-printing rapid prototyping technique (19). 

These techniques have several drawbacks, such as the extensive use of highly toxic organic solvents, and long fabrication periods. Therefore, more recent rapid prototyping techniques have been utilized by tissue engineers to produce three-dimensional porous scaffolds (38). 

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