R.I. Campbell

Surface roughness visualisation for rapid prototyping models

Abstract When considering the use of rapid prototyping (RP), there are many questions a designer might ask. One such question is “what build orientation should be used to minimise the adverse effects of surface roughness?” At present, this decision is often made in an intuitive way or sometimes overlooked completely. This paper describes a methodology and software implementation that provides the designer with a computer graphics based visualisation of RP model surface roughness. This enables the build orientation to be determined as a result of increased designer knowledge. The surface roughness values were obtained through an extensive empirical investigation of several RP techniques. These are used as the database for a visualisation algorithm that represents varying surface roughness of the RP model as colour shading within a CAD image. The nature of the empirical measurements is analysed and the functionality of the software algorithm is described. Examples are given that demonstrate the use and benefits of the methodology. Finally, conclusions are drawn as to the significance of the work and future research directions are outlined.

A Taxonomic Classification of Visual Design Representations Used by Industrial Designers and Engineering Designers

ABSTRACT In the context of new product development (NPD), research has shown that not having a common understanding of visual design representations (VDRs) has affected collaboration between industrial designers and engineering designers. The aim of the research presented in this paper was two-fold. Firstly, to identify the representations employed by industrial designers and engineering designers during NPD from a literature survey. Secondly, to define and categorize these representations in the form of a taxonomy that is a systematic organization of VDRs that are presently dispersed in the literature. For the development of the taxonomy, four measures encompassing orthogonality, spanning, completeness and usability were employed. It resulted in four groups consisting of sketches, drawings, models and prototypes. Validation was undertaken by means of an interview survey and further, presenting the taxonomy at an international conference. The results showed that no issues were raised by the respondents concerning the structure of the taxonomy or its components.

Creating a database of rapid prototyping system capabilities

Abstract Rapid prototyping (RP) potentially offers great benefits when used during the design and manufacturing process. It can help shorten time-to-market, improve quality and reduce costs. However, RP must be used in an effective manner if these benefits are to be fully realised. It should only be used when appropriate, the most suitable system must be selected, data transfer must be optimised and the correct choice of secondary process is essential. For any designer considering the use of RP this is a daunting task, given the range of RP systems and secondary processes that are now available. This paper presents work being undertaken to develop a capability database to assist the designer in making the most effective use of RP. The work is part of a research project whose overall aim is to develop a decision support system (DSS) for RP. The main objective for the database element of the DSS is to represent the capabilities of various RP systems in a logical structure which can be accessed easily. A relational database has been developed which can store a wide range of information about individual RP systems. The database structure facilitates the use of queries which will help the designer to decide on how to use RP. The database has been designed to allow easy expansion, both in terms of new RP systems and new types of information. The implementation of this database is discussed in detail together with some of the queries that can be used. An example of its use is presented to show how it can be of benefit to the design process. Finally, the paper draws conclusions about the usefulness of the database as a stand-alone tool and describes how it will be integrated into the complete DSS.

Additive Manufacturing in South Africa: Building on the Foundations

Purpose – In a previous Rapid Prototyping Journal paper, the authors reviewed the first decade of rapid prototyping (RP) use within the Republic of South Africa (RSA). The paper analysed its strengths, weaknesses, opportunities and threats, and proposed a “road map” for future development. Much has happened in the intervening years since that article was published and this paper seeks to update readers on the current situation in RSA. In particular, it reports the extensive development of research in the field of RP and additive manufacturing (AM).Design/methodology/approach – The paper uses a literature review approach combined with reflective analysis to distill the most important developments within the RP community in RSA since 2004. These are compared to the previous road map to ascertain if there are any required actions that have been overlooked or any additional lessons that have been learnt.Findings – The paper shows that there has been good progress against the previous road map and that current...

Entry level RP machines: how well can they cope with geometric complexity?

Purpose – The purpose of this paper is to examine the limitations of entry‐level rapid prototyping (ELRP) machines when fabricating objects with high complexity.Design/methodology/approach – The literature review provides an overview of RP technologies, followed by a discussion on the different levels of complexity in objects. The paper continues with a discussion on the definition of ELRP, followed by a number of experiments to explore the limitations of an ELRP system when fabricating complex models, and to compare the results obtained with those from a professional RP machine using standardised build parameters and the same acrylonitrile butadiene styrene material.Findings – Of the five complex models that were produced from the Rapman machine, four of them were affected by warping; also, support structures were difficult to remove due to the interwoven build pattern. The study also found that the Rapman parts were coarsely built as opposed to the Dimension parts that were less coarse. The Rapman parts...

Supporting conceptual design with multiple VR based interfaces

Conventional computer aided design (CAD) systems have not provided enough support for conceptual design partly due to the lack of natural and intuitive human–computer interaction. Currently emerging virtual reality (VR) based techniques offer new ways to overcome these obstacles. In this paper, new CAD user interfaces including two-handed operation, haptic interaction, stereoscopic display and auditory feedback are investigated. The contribution of this work is to develop a new direct, natural and intuitive interaction paradigm required to support conceptual design. This paradigm enables designers to take fuller advantage of their visual, auditory and tactile sensorial channels to create, view, touch, hold, manipulate and listen to computer-generated virtual models. This is done more easily and freely in a more realistic three-dimensional (3D) environment through convenient interface device operation. A new conceptual design system called the LUCID system that fully integrates and implements these VR-based innovative interfaces into one design application is presented. As an approach to the next generation of human–computer interfaces for use in the design activity, the LUCID system has shown particular human computer interface benefits to designers during conceptual design based on the outcome from the user evaluation test.

A review of research into the effects of rapid tooling on part properties

Rapid prototyping technologies have introduced a new generation of rapid tooling processes. Many of these rapid tools have been used for injection moulding where the thermal properties of the tool material are critical to the quality of parts produced. Rapid tools are often made from materials with substantially different thermal properties than conventional metal tools. Engineers wishing to make use of these technologies to produce technical prototypes must be aware of the effect this will have on final part properties. Some previous research has been undertaken in this area. Reviews the work done in the field of rapid tooling used for injection moulding. The review shows that, whereas a range of techniques and final part materials has been studied, the results obtained are incomplete and often unexplained. The authors draw conclusions as to why this is so and go on to identify areas for further work that will be pursued.

Monomer transfer moulding and rapid prototyping methods for fibre reinforced thermoplastics for medical applications

Abstract The development of biodegradable materials for surgical applications is a growing area, especially in the area of fracture repair. A fully biodegradable composite has been developed for the manufacture of surgical implants tailored to the patients injury. This composite consists of a poly-ϵ-caprolactone matrix and a biodegradable glass fibre reinforcement. This paper describes two approaches to the manufacture of such implants using geometries derived from patient scan data: a variant of structural reaction injection moulding or resin transfer moulding, and a rapid prototyping method based upon material deposition modelling.

A review of existing anatomical data capture methods to support the mass customisation of wrist splints

Anatomical data acquisition methods used within medicine exhibit various strengths and weaknesses, particularly with regards to accuracy, resolution, patient comfort and safety. Difficulties with data acquisition of wrist and hand geometry are often underestimated, and a suitable method is yet to be identified and standardised to capture skin surface topography to support the mass customisation of wrist splints. The aim of this investigation is to identify a suitable data acquisition method, capable of digitising collected data of the wrist and hand, for manipulation and conversion into a suitable file format to create customised wrist splints using additive manufacturing. Literature suggests that scanning inanimate objects such as plaster casts using multiple three-dimensional laser scanners can provide adequate quality scans with suitable accuracy and resolution, with low cost and low risk to the patient. However, post processing would be required to create a “watertight” digital model suitable for additive manufacturing.

Rapid prototyping in South Africa: past, present and future

Purpose – This paper aims to provide a comprehensive overview of the development of rapid prototyping (RP) within the Republic of South Africa (RSA).Design/methodology/approach – The paper is a general review of the RP research and development effort within South Africa. It begins by looking at the progressive development of RP in the RSA to date. Next, the current situation is appraised in terms of the facilities that are now available, important emerging research areas and the development of human resources. Future prospects are then evaluated through a SWOT analysis.Findings – The main lessons have been learnt in South Africa are as follows: it is never too late to get involved in RP; strong governmental support can enhance the growth of RP; an effective RP association can help to co‐ordinate HE and industry activities leading to a pooling of scarce resources rather than wastage through duplication of efforts; research must be aimed at local priorities to ensure industrial support and government fundin...