Rapid Prototyping Materials Research Articles

Projection display technique utilizing three-color-mixing waveguides and microscanning devices

An integrated-optical three-color-mixing projection display system is demonstrated. This projection display system comprises an optical lens, two microscanners, and a 3×1 planar waveguide device using a new combination of SU-8 and JSR photoresists, which are suitable materials for rapid prototyping of integrated optical circuits. The three-color-mixer fabricated by using a low-cost process has been successfully used for color image generation. This study also demonstrates a surface-micromachined optical scanner using two stress-induced polysilicon plates to raise a horizontal mirror. The electrostatically driven mirror could be used for scanning projection display applications. Experimental data show that the optical scanner has a mirror scanning angle up to 18/spl deg/ using a low operating voltage of 25 V, a submillisecond switching time (<600 μs) and optical insertion loss of 0.85 dB is achieved for multimode waveguides. The development of the proposed project display technology could be promising for integrated optics.

Implementation of a New Adaptive Slicing Algorithm for the Rapid Prototyping Manufacturing System

Rapid prototyping is an automated manufacturing process that quickly builds physical models from three-dimensional (3-D) prototype computer-aided design files. It dramatically speeds up design and manufacturing processes and substantially reduces the cost. This paper presents a new adaptive slicing algorithm for rapid prototyping (RP) processes. The proposed adaptive slicing approach determines the layer thickness based on comparing the contour circumference or the center of gravity of the contour with those of the adjacent layer. Most commercial rapid prototyping systems use uniform slicing procedures with a fixed layer thickness to build parts. To implement the adaptive slicing algorithm, we developed a thermal extrusion based RP mechatronics system equipped with a linear planar servo motor. The RP material is wax. The XYZ table is controlled using a PC based multi-axis DSP motion controller. The RP material flow rate for the thermal extrusion head is controlled using a dc servo motor and motion controller. The Taguchi method was used to analyze the process parameters for the proposed RP system to improve the quality of the RP part. Based on the experimental results, the proposed RP mechatronics system can produce good quality RP parts with the adaptive slicing algorithm. The proposed RP system also implements the high-precision exterior, high-speed interior slicing strategy for STL models.

Modeling and processing of functionally graded materials for rapid prototyping

In this paper, we present an approach to model and process functionally graded material objects by integrating material information along with geometry information in the heterogeneous solid model. Geometry modeling of the objects is done in the CAD system and the STEP standard exchange format is adopted to exchange geometry information between the CAD system and heterogeneous solid modeling system. For material modeling, reference entities were selected and material distribution information in terms of distance functions were specified together. The material information was incorporated with geometry information by attaching distance functions to reference entities as their properties. In processing a heterogeneous solid model, the continuous material distribution is discretized in 2D space rather than in 3D space and only material distribution functions are saved in slice files. The slicing process goes along with the manufacturing process of heterogeneous objects concurrently. Therefore, much memory can be saved. Two examples are described.

Past, present and future of rapid prototyping

This paper provides an overview of the information published in Wohlers Report 2003, a 270-page market study. The report addresses many aspects of rapid prototyping, including: industries served; applications; revenues; unit sales; forecasts. It also provides current information on industry trends and developments in the areas of service providers, advanced approaches to tooling, system manufacturers and technology advances in the USA, Europe, Asia and other parts of the world. The report covers research and development activities, growth trends in CAD solid modelling, rapid prototyping materials, medical modelling, rapid manufacturing and reverse engineering. Wohlers Report 2003 concludes with a discussion of the future of rapid prototyping – where it is headed and what is expected – to assist in strategic and tactical planning.

Application of Rapid Prototyping to Operative Dentistry Curriculum

Computers are becoming an integral part of dental education and dental practice. Rapid prototyping is a technique for the production of solid objects from computer models. The variety of rapid prototyping devices and materials that can be processed is increasing all the time. In this article, the authors present a discriminative learning device and associated exercises for developing visual recognition skills and examine the potential for the application of rapid prototyping to the operative dentistry curriculum. Other rapid prototyping technologies as applied in dentistry are also discussed.

Can rapid prototyping ever become a routine feature in general dental practice?

Rapid prototyping is a technique for the production of solid objects from computer models. The variety of rapid prototyping devices and materials that can be processed is increasing all the time. In this paper, the authors examine the potential for the application of current devices to general dental practice and speculate on developments that could make this technique an attractive prospect within the dental surgery.

Rapid Moulding Using Epoxy Tooling Resin

Rapid prototyping (RP) is fast becoming a standard tool in today's product design and manufacturing environment. Significant benefits in terms of lead time and cost savings have been reported with the use of RP technology. However, these benefits can be derived only during the design and planning stages of a new product where RP parts are produced in small quantities for design evaluation, form fitting, and marketing analysis. The high cost of raw material stock used in current RP systems makes them economically unsuitable even for small-batch production during the product evaluation and manufacturing stages. Further to this, the difference between the mechanical and physical properties of RP and traditional manufacturing materials limits the functionality of RP end products. Rapid tooling (RT) technology has opened up new cost-effective solutions for small-batch production. In this paper, a technique using a rapid soft-tooling approach, namely, aluminium filled epoxy resin tooling for injection mould preparation is successfully explored. An aluminium filled epoxy resin mould is evaluated and the characteristics of the injection-moulded end products are presented.

Rapid Harvest

Deere &amp; Co., the Moline, IL, agricultural equipment giant, has been using rapid prototyping (RP) for about a decade, and is now finishing a wider examination of its entire product development process. Deere is seeking to cut development time by as much as 50 percent, and is looking at how the different prototyping techniques can help that along. Using solid modeling software, as Deere did, is critical for engineering teams wishing to use RP technology. Deere has expended considerable effort recently developing a new product-delivery process (PDP). Such processes can be difficult to hammer out and then follow faithfully, especially in today’s work environment of lean staffs and greater profit pressure. Although RP materials have improved significantly since the first stereolithography machine came into use a little over 10 years ago, none of the current materials to date have the durability required for use on John Deere products sold to customers.

Shaping a thermoplastic object in the desired form without costly mechanical processing

In the field of RPT (rapid prototyping technologies), one of most limiting constraints is the restricted choice of possible materials. The state of the art is such that material choice is heavily dependent on process type, so that, except in a very few cases, the realized prototypes can only give, to the end-user, information about shape and design, or represent no more than a single step in a rapid prototyping process (as in the case of models in polycarbonate, produced with SLS techniques for quick casting). The problem is more acute for injection of plastic materials, because of the large number of available raw materials. In such cases, the only way to obtain a functional prototype, i.e. one produced both with the chosen material and injection method, consists of the realization of a test mold. Note that even though techniques such as high speed milling do indeed reduce the time-to-market, they however, weigh heavily on the budget. This project demonstrates that it is possible, for the case of thermoplastic products, to eliminate the intrinsic limitations that derive from the restricted choice of available materials for rapid prototyping. A process has been implemented which allows injection of different thermoplastic materials into a mold, realized with ceramic powder not yet sinterized. Practical results show that it is possible to shape a thermoplastic object in the desired form without costly mechanical processing.

Rapid Prototyping Materials Rheology

A new technology for printing three-dimensional solid objects from computer-generated images is described. The technology is based on extrusion of a thermoplastic polymer melt as small fibers that bond to form the solid object. This technology is referred to as thermoplastic melt extrusion rapid prototyping (RP). Polymer materials for thermoplastic melt extrusion RP must have the ability to form the structural building blocks of the part. These building blocks are walls, shelves, and bridges. The flow and deformation (rheology) of the melt as it is extruded through the circular die and adheres to the layers already in place govern the process. At this exploratory stage of development, there is no model to specify the extrusion conditions and materials properties relationship to RP performance. Ten marginally acceptable RP materials were identified through extensive RP testing. This study presents the preliminary rheological and thermal analytical characterization of these materials. Characterization of the melt properties is fundamental to the development of a constitutive equation for modeling and to an understanding of the process. The most promising RP materials were found to be crystallizing polymers. Isothermal rheometry and calorimetry measurements were performed to study the crystallization kinetics. Solidification due to crystallization during extrusion is expected to play a key role in RP materials performance.