RAPID PROTOTYPING

Rapid Prototyping (RP) is a technique for direct conversion of three dimensional CAD data into a physical prototype. RP allows for automatic construction of physical models and has been used to significantly reduce the time for the product development cycle and to improve the final quality of the designed product.

Advantages of rapid prototyping Builds complex 3D geometrical shapes Is automated based on CAD models Uses a generic fabrication machine that does not require part specific tooling Requires a minimum of or no human intervention Produces accurate prototypes in a short time at a minimum cost

Prototyping Technologies Base Materials Selective Laser Sintering (SLS) Thermoplastics, metal powders Fused Deposition Modeling (FDM) Thermoplastics, eutectic metals Stereolithography (SLA) Photopolymer Laminated Object Manufacturing (LOM) Paper 3D Printing (3DP) Various materials

Classification of RP techniques 1. Liquid-based techniques 2. Powder-based techniques 3. Solid-based processes

Selective Laser Sintering (SLS)

Advantages of SLS • It produces the toughest components compared to other RP techniques. • A wide range of materials can be used, including metal, plastic, ceramics, wax, nylon, elastomers • A relatively short production time (approximately 1 in/h) is possible. • No post curing processes are needed. • No additional support is required during the building process. • Leftover powder can be reused. • Different parts can be built right on top of others.

Disadvantages of SLS • A rough surface finish is produced due to the stair-step effect. • The time needed to heat up the powder and cool down the model after it has been completed is approximately 8 to 10 h. • Toxic gases are produced especially when plastic materials are fused. • Components are less detailed than those produced by stereolithography due to a high processing temperature and high shrinkage.

Fused Deposition Modeling

Advantages of FDM Quiet, nontoxic, and office-friendly process Fast for small, thin shapes Produces strong parts Cost-effective No need for part cleanup Able to produce multicolored parts using colored ABS

Disadvantages of FDM Slow when making large cross-sectional areas Has to use additional support material Relatively low accuracy and poor surface finish Unable to make complicated parts Limited number of materials available

Stereolithography

ADVANTAGES • High and better dimensional accuracy when compared with other RP techniques. • Unattended system LIMITATIONS • The technique requires support structure. • The components can get warped. • Resin is expensive. • Resins and solvents can be environmentally hazardous.

3D Printing

Laminated Object Manufacturing