Rapid Prototyping Versus Virtual Prototyping in Product Design and ManufacturingC. K. Chua1, S. H. Teh1 and R. K. L. Gay2School of Mechanical & Production Engineering; and 2Gintic Institute of Manufacturing Technology, Nanyang Technological University, SingaporeAbstractRapid prototyping (RP) is the production of a physical model from a computer model without the need for any jig or fixture or numerically controlled (NC) programming. This technology has also been referred to as layer manufacturing, material deposit manufacturing, material addition manufacturing, solid freeform manufacturing and three-dimensional printing. In the last decade, a number of RP techniques has been developed. These techniques use different approaches or materials in producing prototypes and they give varying shrinkage, surface finish and accuracy. Virtual prototyping (VP) is the analysis and simulation carried out on a fully developed computer model, therefore performing the same tests as those on the physical prototypes. It is also sometimes referred to as computer-aided engineering (CAE) or engineering analysis simulation. This paper describes a comparative study of the two prototyping technologies with respect to their relevance in product design and manufacture. The study investigates the suitability and effectiveness of both technologies in the various aspects of prototyping, which is part and parcel of an overall design and manufacturing cycle.Keywords: Product design; Rapid prototyping; Virtual prototyping1. IntroductionRapid prototyping (RP) is emerging as a key prototyping technology with its ability to produce even complicated parts virtually overnight. It enables product designers to shorten the product design and development process. The coming-of-age of this technology is clearly reflected in the inclusion of a stereolithography (STL) file generator in most, if not all, CAD. systems today. The STL file is the de facto standard used by RP systems in the representation of the solid 3D CAD models.While RP is a relatively young technology, virtual prototyping (VP) has been in steady development since the 1970s in many guises. Virtual prototyping is taken to mean the testing and analysis of 3D solid models on computing platforms. Today, VP is often tightly integrated with CAD/CAM software and sometimes referred to as CAE packages. It provides the ability to test part behaviour in a simulated context without the need to manufacture the part first 1.2. Definitions of RP and VPRapid prototyping (RP) is a widely used term in engineering, particularly in the computer software industry where it was first coined to describe rapid software development.This term has also been adopted by the manufacturing industry to characterise the construction of physical prototypes from a solid, powder, or liquid in a short period of time when compared to “traditional” subtractive machining methods. This technology has also been variously referred to as layer manufacturing, material deposit manufacturing, material addition manufacturing, solid freeform manufacturing and threedimensional printing 2.Virtual prototyping (VP) refers to the creation of a model in the computer, often referred to as CAD/CAM/CAE. Virtual or computational prototyping is generally understood to be the construction models of products for the purpose of realistic graphical simulation 1. In this paper, VP will refer to thesimulation, virtual reality and manufacturing process design domains 3.Nevertheless, there are many areas where the distinction between RP and VP is blurred. As RP systems rely on CAD systems to generate the files needed to produce the prototype, it would seem that RP is a downstream process from VP in the product or part development cycle. Indeed, Pratts definition of VP reveals the fact that VP is a term which is loosely used in the prototyping community. As such, it would be appropriate to clearly define both RP and VP.Rapid prototyping will be taken to mean, as above, the production of a physical model from a computer model without the need of any jig or fixture or NC programming. This also includes other related processes and applications which use RP-produced objects, such as rapid tooling.Similarly, VP is defined as the subsequent manipulation of a solid CAD model as a substitute for a physical prototype for the purposes of simulation and analysis, and is not inclusive of the construction of the solid 3D model. VP includes the following functions:1. Finite element analysis.2. Mechanical form, fit and interference checking.3. Mechanical simulation.4. Virtual reality applications.5. Cosmetic modelling.6. Assemblability.The relationships between RP and VP are shown in Fig. 1.Fig. 1. Classification of RP and VP3. Prototyping in SingaporeTwo selected multi-national companies (one American and one French) based in Singapore with significant product deve