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Fig 2.11 an example of a sliced CAD file The main exercise of the slicing process would be to get the intersection points, as all the curves are made up of small sections of lines and planar triangles put together form the facets of the solid model. These intersection points are used in generating the tool path cutter information later on. The rapid prototyping machine is not able to point out which part is solid, because the resultant of the intersection just gives a set of lines. Lin et all in 2002 mentions that the counter clockwise and clockwise direction represent the outer and inner loops respectively. In simple terms, the contours of layers are what the rapid prototyping machine works on as a basis. The solid part is recognized as the left hand side of the contour and the positive direction of the contours follow the counter clockwise direction. The model is ready for processing and tool path generation once the solid part is identified. 2.2.4 Cutter path generation Depending upon the rapid prototyping machine and software the part may require a support material as a base over which the Actual part is made. Small machines like Fab@home, Reprap due to their form factor have limited capabilities and so have to be given the stl model of the support unit if the main model requires a base for its existence. The tool path, which the machine will then use to build the model layer by layer, is dependent on the user. Depending upon the requirement of desired properties of the model in terms of surface finish, strength and build time the users also have a number of options in tool path to chose from. 52
At the very outset of generating the tool path information, it has been found that a number of vectors which are in unsorted state are available. These vectors are not necessarily in sequence and are also not connected. Because of which the layers cannot be identified by the rapid prototyping machine. These vectors need to be arranged in a form which can be then easily read by a rapid prototyping machine. The triangular facets containing a number of vectors in the same plane are connected with straight lines to each other. The stl file contains triangular facets who share edges with other similar triangular facets. Lines are used to connect all the section points which makes the outer surface smoother and then forms the cutter path of the slice. The tool path pattern is dependent upon the choice of the user; it can both be set at 90Degrees or 45degrees and set the same pattern automatically for every layer. The tool path is created with larger air gap in the middle if the parts are to be hollow inside. Fig 2.12 A model being printed with perpendicular tool path However in between adjacent layers tool path patterns are usually set perpendicular to each other for better strength and performance. Fig 2.12 shows a model being printed with perpendicular tool path. When the deposition nozzle is filling in the patterns or tracing the cutter path contours, the output condition is set to be “on”. When the deposition nozzle is moving from one layer to another or is in some kind of transitional state like either travelling home or safe position, the output condition is set “off” so that there is no 53
Page 1 and 2: An Investigation into curved layer
Page 3 and 4: Contents Abstract..................
Page 5 and 6: 3.5.2 Fabepoxy.....................
Page 7 and 8: methodology to print simple curved
Page 9 and 10: List of Figures 1.1 The Rapid proto
Page 11 and 12: 4.3 Parts being tested with Hounsfi
Page 13 and 14: List of Abbreviations 3D: Three dim
Page 15 and 16: Fig 1.1 The Rapid prototyping Cycle
Page 17 and 18: 1.1.1 Stereolithography Stereolitho
Page 19 and 20: The object to be made is first mode
Page 21 and 22: 1.1.5 Laser Engineered Net Shaping
Page 23 and 24: 1.2 Fused Deposition Modeling A det
Page 25 and 26: Fig 1.8 Deposition Head Different t
Page 27 and 28: 900mc is capable of producing parts
Page 29 and 30: noted that the parts built in this
Page 31 and 32: structure. Honeycomb scaffold archi
Page 33 and 34: optimal direction to build a part t
Page 35 and 36: processing treatment was analyzed w
Page 37 and 38: The actual influence of the curved
Page 39 and 40: Separating the Main part with its s
Page 41 and 42: limited to simple models. It could
Page 43 and 44: Fig 2.2 Faces, Edges and Vertices o
Page 45 and 46: 2.1.5 Constructive Solid Geometry C
Page 47 and 48: A STL file is a triangular represen
Page 49 and 50: Fig 2.8 A sample Binary STL File Sl
Page 51: Different processes may either vary
Page 55 and 56: and correction of each point to sat
Page 57 and 58: apid prototyping machine are remove
Page 59 and 60: Fig 2.13 Main Part Fig 2.14 Support
Page 61 and 62: As this text file is to be used wit
Page 63 and 64: mounted to the axes carriage. Timin
Page 65 and 66: Fig 3.1 The deposition head At the
Page 67 and 68: 3.2.3 Assembling Electronics and ca
Page 69 and 70: microcontroller is now disconnected
Page 71 and 72: The relationship between test point
Page 73 and 74: on the mechanical properties and po
Page 75 and 76: 3.5.1 Silicone with other materials
Page 77 and 78: Fab@home machine. Since our require
Page 79 and 80: are printed using the two suitable
Page 81 and 82: The support structure‟s dimension
Page 83 and 84: machine Fig 3.13 Flat and curved la
Page 85 and 86: 4.1 Experimental conditions Chapter
Page 87 and 88: have many factors from contention a
Page 89 and 90: 4.3 Taguchi methods There are two t
Page 91 and 92: Such steps usually identify the nee
Page 93 and 94: Nominal is best Larger is better S
Page 95 and 96: Control of material flow - The lead
Page 97 and 98: Fig 4.3 Parts being tested with Hou
Page 99 and 100: values in all cases are almost doub
Page 101 and 102: level. The other parameters were in
Page 103 and 104:
The finite element method has had a
Page 105 and 106:
performance of finished FDM parts [
Page 107 and 108:
ehaviour with failure occurring at
Page 109 and 110:
Fig. 2 (a) is the thin curved part
Page 111 and 112:
Table 5.1 Property data: Fabepoxy M
Page 113 and 114:
optimum number. The final finite el
Page 115 and 116:
Fig. 5.11 Load and boundary conditi
Page 117 and 118:
overall deflection pattern of two s
Page 119 and 120:
Fig. 5.13 Variation of compressive
Page 121 and 122:
Fig. 5.15 shows the overall deforma
Page 123 and 124:
The effectiveness of the deposition
Page 125 and 126:
[11] M. Greul, T. Pintat, M. Greuli
Page 127 and 128:
[32] Philip J. Ross, 1988, “Taguc
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