5。2Rapid mass production

This is developed for the mass customization such as the mass production of dental appliance by Aligh Inc, and the mass production of hearing aid in the ear (ITE) by Phonak Group and Simens Hearing  Instruments。 The Aligh Inc。 used SL technics to produce invisible dental bracketless appliances according to the person- alized features of a certain patient。 They had produced 3 million appliances by Dec。 2002。 And the ITE was also designed and manufactured according to the fea- ture of each client。 This type of customized mass pro- duction will be an important application of RPM in the future。

5。3Going deep into nano-/micro-RPM

The nano-/micro- technology is one of the hottest spots in 21st century。 It is believed that many important ap- plicable techniques will derive from this field。 As an advanced forming method, RPM is very competent in manufacturing complicated 3-D nano-/micro- struc- tures that other traditional methods can not afford。 It will play an important role in nano-/micro- structures such as micro electronic mechanical system (MEMS), biochip, nano circuit, molecule motor, sensitive chemi- cal test system, and high-throughput drug screening systems。

5。4Application in direct metal forming

Metal remains the main material in industry, and the direct metal forming based on RPM is one of the most concerned problems in science and industry field。 At the conference in Frankfurt, Germany in Dec。 2000, Terry Wohlers, the president of GARPA, Dr。 Roger Spielman  from Boeing,  and  Dr。  Philip  Dickens from

YAN Yongnian (颜永年) et al：Rapid Prototyping and Manufacturing Technology … 11

De Montfort University all agreed that it was the time to emphasize rapid part manufacturing。

At present, direct accumulated forming parts  made of ferrous metals, non-ferrous metals, and other high- temperature alloys are still difficult in application。 However, the rapid metal forming techniques will be- come the mainstream of the progressive laser netshap- ing technics such as high-power laser sintering, laser coaxial powder feeding, and 3-D welding。 And there are already 12 manufacturers that are able to provide direct metal forming equipments。

This powerful technique can directly manufacture special-property and functional metal parts with   such as titanium, tungsten, and high-temperature  alloy。  It can be applied in aerospace, national defense, and medical fields。 For example, functional precious metal pieces such as impeller blades and the turbine disk can be directly formed with special alloys, high- temperature alloys or other advanced materials。 The Boeing has already tried to use RPM to manufacture parts for space station and F18 warplanes。 These parts such as in satellites are mostly of composite materials, have freeform surface, and are produced in small batch, which are especially for RPM。

5。5Application in biomanufacturing

It is known that there is a great worldwide demand for kinds of artificial alternatives。 BM based on RPM is a very useful technique in this field。

The design and manufacturing of prosthesis are al- ready mature。 There were lots of reported clinical sur- geries about orthopedic prostheses, artificial joints, and craniofacial prosthesis。 We succeeded in artificial hip arthroplasty repair and implanted skull prosthesis re- pair。 Polyurethane (PU) ear prosthesis was also proved to be potential in clinic。

Based on indirect cell assembling, now biomanufac- turing of structural tissues such as skin, bone, cartilage, large vessel, and muscle tendon have made great pro- gress。 Some of them have been commercialized。 With LDM technics, 15 mm segmental rabbit radio bone de- fect, 20 mm segmental dog radio bone defect, and rab- bit articular cartilage defect had been successfully re- paired。 Based on a developed RP dissolving-depositing technology, we successfully created multi-branch, multi-layered vascular scaffolds and the results of dog femoral vein defect repair were good。