Invention Journal of Research Technology in Engineering & Management (IJRTEM) ISSN: 2455-3689 www.Ijrtem. com Volume 3 Issue 6 ǁ September-October 2019 ǁ PP 43-49
Industrial Computed Tomography as an excellent tool for wall thickness investigation comparing CAD model and the real part made by EN AC-42100 aluminum Monika Barciewicz 1
(Laboratory of Coordinate Metrology, Faculty of Mechanical Engineering, Cracow University of Technology, Poland
ABSTRACT: This paper presents how industrial computed tomography can be used in the automotive world to quality control of aluminum alloys parts. For engineers in Research and Development Center working on the design and manufacturing process, it is essential to produce a real part with quality following customer requirements. The whole process takes time. New car parts are developed usually three to five years. Project Teams involved in designing process, production and logistic work parallel. Each team has to cooperate to create a car with all compatible systems. There are many repetitive steps in each project stage. The work as Mechanical/CAD Engineer is focused on designing CAD model, calculations, stack-ups, simulations analysis and the tests on real parts. All these activities are repeated until the final part will be produced. But even when serial parts are producing the changes come up and the whole re-designing process starts again. As mentioned, it is crucial to catch all internal and external defects. In this case was made initial sample test before design validation. The CT scan of the outlet tank (real part) was overlapped with its CAD model to compare wall thickness. The product is made by EN AC-42100 aluminum.
KEYWORDS: CAD model, cast aluminum part, industrial computed tomography, initial sample test, quality control
I.
INTRODUCTION
As Original Equipment Manufacturer (OEM) product development is a complicated process. Usually, it takes three to five years. Engineers working in Research and Development Centers has to first calculate and design mockup of the product. During the design development of each car system, the packaging and some customer requirements are changing. The Project Team consists of people working simultaneously on all calculations, 3d modelling, analysis stack-ups, simulations, tests and quality control of both - products and their forms necessary to manufacture. The mockup develops to prototype and this is the most important and intensive stage. At each development process stage, quality control is crucial to catch all internal and external defects. This is particularly important concerning cast components. Focusing on the prototype stage of the outlet tank, industrial CT helps to catch all problems with wall thickness and improve the design of the 3D CAD model and manufacturing process. As a cooling system part made by aluminum alloy, the outlet tank must meet the strict requirements needed for all performances. Computed tomography as a non-destructive testing method is an excellent tool for controlling and improving both the manufacturing process (casting) and the 3D modelling of tested components. More about technical aspects and application of CT in the automotive industry find in my previous work reference [1] and [2]. In this case was made initial sample test before Design Validation. Always before project stage - Design Validation, the first serial manufactured part must be checked before design approval. The initial sample test report (ISTR) is a documented evidence about the series-production readiness - the repeatability of your module inconsistent quality. For this purpose, a predefined quantity from the produced batch is used for the initial sampling. "Initial sample" refers to products which are manufactured for the first time under standard and realistic conditions. Any further production and product release of such a product has to take place under constant conditions, based on the initial sample [3]. The initial test purpose was the scan of outlet tank wall to compare wall thickness with the attached 3D model and approve calculated real weight of the sample.
II.
CASE STUDY - RESEARCH DATA OF INITIAL SAMPLE TEST
The 3D CAD model of the outlet tank was designed in Catia V5. Designing process was based on casting parts designing principles, company experience in designing of thermal systems’ parts, customer requirements and norms, and designer’s experience. The model fits to its cooling module and the car environment. All technical parameters meet automotive customer requirements of exchanger’s performance. The sample was produced by the casting process. Is made by EN AC-42100 aluminum. The initial sample test - quality control was done using CT scanning of the first produced outlet tank.
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Industrial Computed Tomography as an excellent tool for wall… Research was conducted using Industrial CT Nikon XT H 225. Data analysis was carried out using software dedicated for the tomograph. CT scanned sample in STL format was compared with its 3D CAD model. Figure 1-4 refers to the general views of the sample. The main technical specification from the part’s drawing necessary for correct interpretation of test results: 1. The drawing takes priority over 3D model but dimensions not shown shall be taken from 3D model with tolerances according to general cast tolerance standard: PN ISO_8062:1997 CT9 for sandcore, PN ISO_8062:1997 CT8 for mold and general machining tolerance according to standard: PN ISO_2768-cK. 2. Approximate wall thickness according to 3D MODEL +1/-0.5mm. 3. Max flash allowed 0.5mm. 4. Part shall be clean, free of oil, machining chips. burrs and sharp edges are not allowed. 5. INTERNAL CLEANLINESS: • total debris mass not exceed 5mg • no single debris particle to be larger 3.175mm in any lineal direction • no single debris to be larger than 2.58mm2 in any single area • metallic particles may have dim. no greater than 0.5mm x 0.5mm x 0.5mm • non metallic particles not including glass fibers may have dim. no greater than 0.7mm x 0.7mm x 0.7mm • soft ( non-metallic) fibers greater than 20:1 length to width ratio are acceptable if the fibres are less than 5mm in length and the total count is less than 5 • individual glass fibers (minimum length to width ratio 20:1) must weight less than 0.3mg • particles for dimensional analysis include sand, scale, cleaning shot, machining chips, weld spatter, slag, or particles not easily broken with a probe. 6. Casting porosity according to VW 50097. 7. Sealing areas: F3/0.4/A5/P0.2. 8. Machined areas: F4/3/A4/P0.5. 9. Non machined areas according to ASTM E155 CLASS 3. 10. Thickenings and datums according to ASTM E155 CLASS 4. 11. Control of casting manufacturing process according to customer standard. EN AC-42100 aluminum is an aluminum alloy formulated for casting. 42100 is the EN numeric designation for this material. Additionally, the EN chemical designation is AISi7Mg0,3. The main advantage of used material is fact that, among cast aluminum alloys, the composition of EN AC-42100 aluminum is notable for containing a comparatively high amount of silicon (Si) approximately 6.5% to 7.5%. Silicon is used to improve casting fluidity and lower melting temperature. It also has a strengthening effect. EN AC-42100 has the highest electrical conductivity among Euronorm (EN) cast aluminums. In addition, it has a moderately high melting temperature and a moderately high thermal conductivity [4].
Fig.1. Front view of the outlet tank.
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Industrial Computed Tomography as an excellent tool for wall‌
Fig.2. Right view of the outlet tank.
Fig.3. Left view of the outlet tank.
Fig.4. Bottom view of the outlet tank.
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Industrial Computed Tomography as an excellent tool for wall‌ Analysis of the comparison of the real part scan with the 3D model : Figure 5 shows variance distribution of tested wall thickness. Next figure 6,7 and 8 presents the real part and CAD model comparison with sign variations measured in mm. Wall thickness measurements in mm are on the last three figures: 9, 10 and 11.
Fig.5. Real part of the outlet tank and CAD model comparison. Variance distribution.
Fig.6. Variance - real part and CAD model comparison. View no: 1.
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Industrial Computed Tomography as an excellent tool for wall‌
Fig. 7. Variance - real part and CAD model comparison. View no: 2.
Fig.8. Variance - real part and CAD model comparison. View no: 3.
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Industrial Computed Tomography as an excellent tool for wall‌
Fig. 9. Wall thickness analysis. View no: 1.
Fig.10. Wall thickness analysis. View no: 2.
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Industrial Computed Tomography as an excellent tool for wall‌
Fig.11. Wall thickness analysis. View no: 3.
III.
CONCLUSION
The initial sample test presents areas with wall thickness problems. According to dimensions and tolerances on the technical drawing and note: Approximate wall thickness according to 3D MODEL +1/-0.5mm, it shows that there are areas do not meet the specification. As it comes out of the graph and variances visualization the main problem is with the areas with variations greater or equal +1mm and between -0,5mm and -0,97mm. The technological process limitations cause inconsistencies in the wall thickness of the initial sample of the outlet tank due to the 3D CAD model. Calculated real weight of the sample - 1025,2g - approved.
REFERENCES Journal Papers: 1. M. Barciewicz, A. Ryniewicz, The application of computed tomography in the automotive world – how industrial CT works, Technical Transactions Vol. 9, 2018, 181-187 2. M. Barciewicz, A. Ryniewicz, Computed tomography as quality control technique in the 3D modelling of injection-moulded car system components, Technical Transactions Vol. 9, 2018, 189-199 Web sites: 3. https://www.kuttig.eu/en/company/quality/istr.html 4. http://www.reliablecastings.com/casting-design-principles_19.html
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