4.11 Gearbox Housing - Industrial
 
 

Capturing the geometry of an existing part can play a critical role if this data can successfully be used for a FEM or process analysis. The computer modeling and analysis method can the be applied to assist in the manufacturing process. A 3D electronic format of the part is required to perform an analysis or process modeling of a manufacturing process. 3D CAD and STL files existed, but these files proved to be unacceptable for FEM analysis. The STL file was generated from the 3D CAD file. A new STL file generated from the CAT scanning data may solve the problem.
 
 

4.11.1 Background
 
 

The quarter scale SLA prototype was CAT scanned using the GE. CAT scanner at Hydromed Hospital based in Bloemfontein. The 2D CAT slices were again stored on 4mm DAT magnetic tape. 2D CAT images of various positions were stored on film for record.
 
 

4.11.2 Conclusion
 
 

2D CAT images were checked during scanning. The window settings were optimized on the CT computer. It is again clear that the material what the part is made of plays a major role. The SLA prototype in made of an epoxy polyester. Measurements were taken of the partís wall thickness and compared to measurements taken from the CAT scan images. In general, the CAT scan images proved to be 0.4 to 2mm thinner than the actual part. Again, the threshold was set to the optimum. Clearly, the SLA material was not suitable to CAT scanning. Referring to an earlier section (3.6), materialís density and atomic number are important factors to obtain an acceptable CAT scan image. A lot of detail was lost at the thinner wall sections and can be seen from the generated 3D images. Due to the material, the process could not be fully evaluated.

4.12.2.1. Images
 
 
 

 

 

Figure 4.11.2 

3D Reconstructed Gearbox housing.
 
 

 

Figure 4.11.2 

3D Reconstructed Gearbox housing.

 
Figure 4.11.2 

3D Reconstructed Gearbox housing.

 

 

4.11.3 Gearbox Housing Data Sheet:
 
 
 
  Description Options (Default) Data

 

1 CT Image Names   1s6I.*
2 Patient/Project Name   1s6I
3 Number of First Input Image   E6281S6I1.CT
4 Number of Last Input Image   E6281S6I79.CT
5 Number of First Output Image   1S6I1_1.000
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 CCGEADVA
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) 0
17 Distance Between Slices (mm) 1
18 Slice thickness (mm) 1
19 Pixel Size SQ. F.O.R./Nr. Hor. Pixels (mm) 0.47
20 Gantry Tilt Angle Degrees 0
21 Field of Reconstruction/View (mm) 240
22 Number of Images   79
23 File Size of CAT Image kb 270-280
24 File Size of Converted Image kb 11-23
25 .3dd file size Mb 3.2 *.srf
26 .STL file size Mb 17
27 RP Method (SLA,FDM,OTHER) SLA
28 .IGS file size Mb -
29 RP Slice file size Mb 19
30 RP Download File size Mb 16
31 Grow Time Hour 6
32 Tip size (T12, T25) -
33 Slice Thickness (0.01", 0.014") 0.01"
34 Finishing Time Hour 3
35 Processing Time Hour 2
36 Data Retrieval Time Hour 2
37 Total Cost Rand =8*250=2000

 

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