Rapid Prototyping or Layered Manufacturing
Design and Rapid Prototyping Laboratory
Associate Professor Ashok V. Kumar
Department of Mechanical and Aerospace Engineering
Layered Manufacturing, also known as Rapid Prototyping or Solid Freeform Fabrication is a new class of manufacturing technologies that has recently emerged. They are characterized by a layer-by-layer build-up of parts. These technologies promise to revolutionize manufacturing in many ways. Due to the layer-by-layer building approach, it is possible to create significantly more complex parts in one fabrication step than was previously possible. In addition, due to the relatively simple process planning required, the potential has been demonstrated to automatically fabricate a part under computer control given a solid model of the part. While early applications were to make prototypes of design, more recently these technologies have been applied to directly produce real parts or the tools / molds necessary to mass produce real parts.
We are developing a novel Layered Manufacturing method called Electrophotographic Layered Manufacturing (ELM) which uses electrophotography to deposit powder layer by layer to construct parts. The department also has a rapid prototyping facility based on Fused Deposition Modeling technique.
Electrophotographic Layered Manufacturing (ELM)
- A novel powder based Layered Manufacturing technique
- Uses two different types of powder
- Part powder and
- Support powder
- Powders are deposited using electrophotography
- Part powder is consolidated by fusion, compaction and / or sintering
Advantages of electrophotography
- very fine powder can be used (5-20micron size)
- possible to print in gray scales
- allows mixing of powder in a controlled fashion
- can create composition gradients within the part (gradient materials)
- possible to embed electronics into parts by printing circuits
Deposition of powders and consolidation of part
- Powders deposited layer by layer
- Two powders are used in each layer
- Part powder is deposited in the shape of the part cross-section
- Support powder surrounds the part powder
- Part powder consolidated by compaction / sintering / fusing
- Support powder has relatively high melting point and does not easily consolidate
Advantages of the two powder method
- Applicable to a wide range of materials
- No special support structures required
- Compacting and sintering the two-powder layers
- can produce fully-dense parts
- significantly improve strength and toughness
- be an alternative to Hot Isostatic Pressing (HIP)
- Composite material parts possible (including metal matrix composites)
- Special surface treatments possible by adding appropriate additives to support powder
Acknowledgment
This research is sponsored by the Office of Naval Research (ONR) under grant no. N00014-98-1-0694