Chapter 6 Extrusion-Based Systems PDF

Chapter 6 Extrusion-Based Systems  Extrusion-Based Systems Objectives: – Discuss on: Extrusion-based systems Basic principles – Material loading; Liquification; Extrusion; Solidification; Positional control; Bonding; and Support...

Chapter 6 Extrusion-Based Systems  Extrusion-Based Systems Objectives: – Discuss on: Extrusion-based systems Basic principles – Material loading; Liquification; Extrusion; Solidification; Positional control; Bonding; and Support generation Plotting and path control Fused deposition modeling (FDM) from Stratasys – FDM machine types Materials Limitations of FDM Bioextrusion – Gel formation; Melt extrusion; and Scaffold architectures Other systems – Contour crafting; Nonplanar systems; FDM of ceramics; and Reprap and Fab@home  Extrusion-Based Systems Assignment: – Read Chapter 6, Pages 147 - 173 Homework: – Exercises: 1-6 Videos – METROM PM1000 - SEAM screw extrusion additive manufacturing at Fraunhofer IWU » https://www.youtube.com/watch?v=aTJ5OwluGhk – Design Dictionary: Extrusion 3D Printing » https://www.youtube.com/watch?v=2P1DjilPBS4 – How A 3D Printer Extruder Works » https://www.youtube.com/watch?v=52chDT-IAxw  Extrusion-Based Systems Two primary approaches when using an extrusion process: – Use temperature as a way of controlling the material state Molten metal is liquefied inside a reservoir so that it can flow out through the nozzle and bond with adjacent material before solidifying. This approach is similar to conventional polymer extrusion processes, except the extruder is vertically mounted on a plotting system rather than remaining in a fixed horizontal position. – Use a chemical change to cause solidification A curing agent, residual solvent, reaction with air, or simply drying of a “wet” material permits bonding to occur. Parts may therefore cure or dry out to become fully stable. This approach may be more applicable to biomedical applications where materials must have biocompatibility with living cells and so choice of material is very restricted. Industrial applications may also exist, perhaps using reaction injection molding- related processes rather than relying entirely on thermal effects. Extrusion: where: m represents flow exponent;  represents fluidity. Position Control: 6.3 Plotting and Path Control: Melt Extrusion: Other Systems: Contour Crafting