4.9.1 Background
 
 

Once again the geometry was required that was used to produce injection mould tooling. The rubber seal was taken to Krugersdorp Hospital to capture the geometry. One millimeter thick slices were required to obtain sufficient detail of the seal’s geometry. Three data sets of sixty slices each were made due to the maximum amount of slices that can be scanned at one time. The limitations are related to the computer processing capabilities, hard drive space and X-ray tube cools down periods. The seal was aligned in two axis with the visual aids available on the CAT scanner. A flat section of foam was used to suspend and separate the seal from the scanner’s table. This would help in later during the data conversion and processing stages. CAT scanning took place at 130kV.
 
 

4.9.2 Conclusion
 
 

The threshold, type of material and material cross sectional wall thickness here plays a cardinal role. One can easily adjust the threshold to vary the wall or cross section. Any imperfection will also be captured with this method. A fair amount of editing can be applied to solve this problem. If the material cross section is to thin or if the material density is too low, a poor CAT image will be generated. To improve the poor data that was captured, the threshold can be increased. The threshold can be increased to such an extent that the 2mm-wall thickness can be thickened to 3.5mm. It is therefor important that some form of reference or verification is implemented every time. It is also required by the ISO 9000/1 standards, that results and processes can by traced and verified. It was again clear that the correct tools are still not in place at the TCT, CSIR, to perform the tasks. STL data manipulation tools are requited that can perform boolean operations, section 3D STL geometry, fix and verify STL data, tools that can generate machine tool paths from STL data. STL format is one of the easiest data format obtainable from RE, and it is therefore important to have the correct software programs that can manipulate STL format files.

4.9.2.1. Images
 
 
 

Figure 4.9.2 .1 3D reconstructed image of the motorcar door window rubber.	Figure 4.9.2 .2 3D reconstructed motorcar door window rubber.
Figure 4.9.2 .3 3D reconstructed motorcar door window rubber.	Figure 4.9.2 .4 3D reconstructed motorcar door window rubber.

 

4.9.3 Rubber Seal Data Sheet:
 

	Description	Options (Default)	Data
1	CT Image Names		mirror.00
2	Patient/Project Name		spiel.pat
3	Number of First Input Image		mirror1.000 @ 34.5
4	Number of Last Input Image		mirror1.147 @ 179.8
5	Number of First Output Image		000
6	CT or MRI	CT, MRI	CT
7	Horisontal Nr. Of Image Pixels	0 to 65535 (265,512,1024)	512
8	Vertical Nr. Of Image Pixels	0 to 65535 (265,512,1024)	512
9	Number of Images per File	(1)	1
10	File Swap Format (0,3)	0,3	CCELSC
11	Pixel Type	B,UB,S,US,L,UL,F	-
12	Header Size	*see formula below	-
13	Inter Image Header Size	0	-
14	Add Value	0 to 4095	-
15	Scale Value	0 to 4095	-
16	Table Position	(mm)	34.5
17	Distance Between Slices	(mm)	1
18	Slice thickness	(mm)	1.2
19	Pixel Size SQ.	F.O.R./Nr. Hor. Pixels (mm)	0.684
20	Gantry Tilt Angle	Degrees	0
21	Field of Reconstruction/View	(mm)	350
22	Number of Images		147
23	File Size of CAT Image	kb	27
24	File Size of Converted Image	kb	19-22
25	.3dd file size	Mb	0.234
26	.STL file size	Mb	8.9
27	RP Method	(SLA,FDM,OTHER)	-
28	.IGS file size	Mb	-
29	RP Slice file size	Mb	-
30	RP Download File size	Mb	-
31	Grow Time	Hour	-
32	Tip size	(T12, T25)	-
33	Slice Thickness	(0.01", 0.014")	-
34	Finishing Time	Hour	-
35	Processing Time	Hour	1
36	Data Retrieval Time	Hour	3
37	Total Cost	Rand	600+800=1200