Selective Laser Sintering (SLS) or Laser Sintering (LS) allows functional parts to be produced in a wide range of powdered materials using a dedicated machine, and is thus gaining popularity within the field of rapid prototyping. Two current manufacturers of LS equipment and materials are EOS GmbH and 3D Systems. The PA2200 semi-crystalline polyamide powder studied here was developed by EOS and was processed using the 3D Systems Sinterstation 2500 HiQ LS machine. One of the advantages of employing LS is that the loose powder of the building chamber can be recycled. However, the properties of some recycled powders such as polyamide 12 (PA 12) deteriorate by comparison to those of fresh powder. Fabricating parts using only new powder, although providing the best quality, is considerably more expensive than using recycled powder. On the other hand, using recycled powder creates the problem of the coarse, rough, and uneven surface texture. This thesis examines LS fabricated parts which are affected by the "orange peel" phenomenon due to the usage of recycled PA 12 powder. This problem must be addressed before the technology can be widely accepted. This thesis presents the problematic areas and proposes solutions to manage and utilise the recycled powder. Further, the thesis discusses experimental work on the deterioration or ageing of PA 12 powder properties in the LS process, the microstructure of "orange peel" texture and the improvement of part surface finish to avoid the "orange peel" problem.
| Identifer | oai:union.ndltd.org:bl.uk/oai:ethos.bl.uk:584021 |
| Date | January 2007 |
| Creators | Yusoff, Wan Ahmad Yusmawiza |
| Publisher | Cardiff University |
| Source Sets | Ethos UK |
| Detected Language | English |
| Type | Electronic Thesis or Dissertation |
| Source | http://orca.cf.ac.uk/54575/ |
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