META

Rapid prototyping (RP) pertains to a class of related technologies that are used to fabricate physical models directly from computer-aided design CAD) data sources. These methods are unique in that they add and bond materials (e.g. liquid or powder based) in layers to form objects. Such systems are also known by the general names of freeform fabrication (FFF), solid freeform fabrication (SFF) and layered manufacturing. Today's additive technologies offer advantages in many applications compared to classical subtractive fabrication methods such as milling or turning:

• 1. Objects can be formed with any geometric complexity or intricacy without the need for elaborate machine set-up or final assembly.
• 2. Rapid prototyping systems reduce the construction of complex objects to a manageable, straightforward, and relatively fast process.

In addition to prototypes, RP techniques can also be used to make tooling (rapid tooling) and even production-quality parts (rapid manufacturing). For small production runs and complicated objects, rapid prototyping is often the best manufacturing process available. This has resulted in their wide use by engineers as a way to reduce time to market in manufacturing, to better understand and communicate product designs, and to make rapid tooling to manufacture those products. Surgeons, architects, artists and individuals from many other disciplines also routinely use the technology.

RP models have been found to be particularly useful in many applications such as diagnostics, treatment planning, procedure practice/simulation, and consultation. There are of course limitations associated with every technology. RP isn't a solution to every part fabrication problem. After all, CNC technology is economical, widely understood and available, offers wide material selection and excellent accuracy. However, if the requirement involves producing a part or object of even moderately complex geometry, and doing so quickly - RP has the advantage. However, the reference to "rapid" has to be taken in relative terms. Typically, RP processes require from three to seventy-two hours to build, depending on the size and complexity of the object. RP does not produce perfect parts and requires some form of finishing process. Part volume is generally limited to 0.125 cubic meters or less, depending on the RP machine. It's very easy to look at extreme cases and make a determination of which technology route to pursue, CNC or RP. For many other less extreme cases the selection crossover line is hazy, moves all the time, and depends on a number of variably-weighted, case-dependent factors. While the accuracy of rapid prototyping isn't generally as good as CNC, it's adequate today for a wide range of exacting applications.

Project: Assembly-based Rapid Prototyping

Description:

Various forms Rapid Prototyping (RP) technologies are being employed extensively in fields ranging from scientific to entertainment. Despite its diversity, the basic underlying principle is that parts are built gradually by adding materials layer-by-layer. RP is often slow and have limited build materials. An ideal RP system would be able to create prototype components from a wide range of materials (e.g. MDF, plastics and metals) and produce objects in hours rather than days.

RPBloX is a novel assembly-based RP technique proposed to prove the feasibility of a system that has the potential to deliver this ideal performance. The system can supplement current RP techniques or function as a standalone. The methodology involves a cellular approach to build prototypes. Rather than slicing up the CAD model into numerous thin sheets, RPBloX segments the model into 3D cells (or BloX) of varying sizes. In contrast to current RP technology, conventional machine tools such as CNC machines and robots are used to manufacture and assemble the cells. Consequently, production costs could be significantly reduced without forfeiting accuracy and timeliness.

This project seeks to combine sophisticated CAM software and automated assembly technologies to demonstrate that a non-layered method of rapid prototyping can be engineered. Crucial to the feasibility of the assembly based manufacturing system envisaged are the software algorithms required to support several different forms of geometric reasoning and the robotic technology needed to precisely locate variable shapes. The programme of research addresses both of these fundamental issues.

Scope:

The research aims to integrate conventional shop floor technologies (CNC, Robots) via intelligent software for RP. The software objectives are to develop intelligent subdivision and assembly planning algorithms to automatically generate machining and assembly codes. The hardware objectives involve manufacturing and robotic assembly of BloX.