Abstract: The rapid prototyping and manufacturing technology (RPM), is an integration of many different disciplines。 It is based on an advanced dispersed-accumulated forming principle and originated from 1980s。 It generates an entity by first forming a series of layers according to the dispersed section information of the digital model, and then piling the formed layers sequentially together。 It is capable of forming parts with complicated structures and non-homogeneous materials。 Traditional RPM techniques are mainly used as prototypes in product invention process, such as stereolithography, three-dimensional printing, laminated object manufacturing, and fused deposition modeling。 Later, with the progress of material and enabling tech- nology, many new RPM techniques emerged out and have been already applied in the fields such as rapid tooling/moulding, direct formed usable part, nano-/micro-RPM, and biomanufacturing。 This high flexible digi- tal manufacturing method has a likely ability to become an almighty forming technology。83138

Key words: rapid prototyping; rapid manufacturing; dispersed-accumulated forming; rapid tooling; rapid moulding; biomanufacturing

Introduction

From thousands of years of humankind history, we can see that most of our civilization was founded on the base of forming/shaping technology, and actually the history of humankind civilization has been  propelled by the evolvement of forming/shaping technology。 And we can conclude that our beautiful future will benefit a lot from the frontier field of modern forming technol- ogy which we are now devoting in, such as rapid pro- totyping and manufacturing (RPM) and its derivative techniques。

Received: 2008-11-09; revised: 2009-03-03

* Supported by the National Natural Science Foundation  of China (No。 50575118)

** To whom correspondence should be addressed。

E-mail: dmeyyn@mail。tsinghua。edu。cn; Tel: 86-10-62783565

Modern forming/shaping science is the science that researches  on  orderly  organizing  the  materials  into a  three-dimensional  (3-D)  part  with determined shape and functions。 According to the method for organizing the materials, it can be pided into four basic categories:

(1)Removal forming an ancient method to form a part by orderly removing redundant materials from primal rough model, such as traditional lathing, milling, planing, drilling, grinding, laser cutting, and electrical discharge machining (EDM)。 It is now the most impor- tant processing method。

(2)Forced forming an ancient method to form a part by imposing external constraints like a cavity or exerting pressures onto the material stuff, such as tradi- tional forging, casting, and powder metallurgy。 It is mostly used for roughcast while some like precision casting   and   precision   forging   are   aslo   for direct

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end-forming of net or near net shape。

(3)Dispersed-accumulated forming (as shown in Fig。 1) a novel method to form a part by first dispers- ing the materials (gas, liquid or solid state) into  points or lines, and then piling up them into layers and bodies。

(4)Growth forming the forming process of all natural organism bodies (plants, animals, etc), mostly relied on the proliferation and self-assembly process of materials like cells; for example, the spiral fractal ge- ometry of a trumpet shell is developed from its natural growth process。 It is now the most complicated and highest forming level。

Fig。 1    Illustration for dispersed-accumulated forming

Since the late of 20th century, the original removal and forced forming methods have been hard to meet all demands in increasingly competitive manufacturing market of globalized economy, and a personalized and flexible forming method has been required。 On the other side, computer-aided design (CAD) technology, laser technology, numerical control technology, and material technology have been rapidly developed。