e-ISSN: 2582-5208 International Research Journal of Modernization in Engineering Technology and Science Volume:02/Issue:12/December -2020
Impact Factor- 5.354
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SELECTION OF SHEET METAL BASED ON CURRENT DENSITY FOR INDUSTRIAL APPLICATION Tanmoy Bera*1, Shiromani Dhar Diwedi*2, Yashika Joshi*3 *1PEC
University of Technology, Chandigarh(UT), India *2CIPET,
*3Graphic
Lucknow, India
Era Deemed University, Dehradun, India
ABSTRACT When it Comes to selection of Conducting material for electro-mechanical application we need to know the current density (J) of the conductor. As Current density is the measurement of current flowing through a specific cross-section area of a conductor. Therefore, we need to determine how much current (I) can pass through the specific cross-section (A) without reaching the melting point of the conductor. So, that the product is more reliable and robust. To set a criterion for selection we investigated by performing Design of Experiment with 4 Conductors used in automobile industry namely ETP-Copper (Cu-ETP), Phosphor Bronze (Pb), Brass and Steel. Various values of Current were made to flow through each material and temperature rise reading was recorded. We analyzed the observation and plotted a graph of Temperature Change (ΔT) Vs Current (I) which helps to determine the Current Density value w.r.t Temperature Change. Using the Current Density value an engineer can further research and calculate the Maximum Current that can flow the minimum cross-section of the Conductor.
I.
INTRODUCTION
We see many Market Quality problem reported due to heat generated in a conductor and melting the thermoplastic associated with it through Injection Molding. The root cause for the failures is the material selection was not as per the current carrying capacity requirement. A materials Current Carrying capacity is defined by its property of Current Density (J), which depends upon Current (I) and Area of Cross-section (A). The empirical formula is:
To Calculate the maximum Current (I) which can flow through conductor, An Researcher/Designer must know the material property i.e., Current density (J) and Minimum area of Cross-section (A). Cross-section is controlled designed parameter can be reduced or increased as per the requirement. But Current Density of a material remains unknown as any amount of current can be passed through the conductor but leading rise in temperature. Hence, the Researcher cannot determine the allowable current that can flow through the Material for safe application. Therefore, through this experiment we were able to determine the Current Density as per the allowable temperature rise in the part or product.
II.
METHODOLOGY
To establish a criterion for selecting sheet metal based on current density we conducted Design of Experiment and analyzed the results. For this we made strips of Copper, Phosphor Bronze, brass and Steel were wire cut in dumbbell shape. And current was made to pass through it while recording the Temperature rise. Input Design Values: • Input voltage 12V • Input Current 11. 22, 33, 44, 55 and 66A • Copper Strip (as per IS 1897) /Brass Strip (as per IS 410)/Steel Strip (as per IS 513) of 3 mm2 cross-section & Pb Strip (as per IS 7814) of 2.4mm2 • wires with cross-section 4mm2
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e-ISSN: 2582-5208 International Research Journal of Modernization in Engineering Technology and Science Volume:02/Issue:12/December -2020
Impact Factor- 5.354
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Output Design Values required: • Maximum Temperature rise ∆T (°C) Vs Time (minutes) values obtained at different current values (11, 22, 33, 44, 55 and 66 A) Tools used: Power Supply, Multi-meter connected with laptop, Thermal Coupler, Relay, Ammeter, soldering equipment and connecting wires.
III.
MODELING AND ANALYSIS
Figure 1 graph is plotted from the experiment which will be used to determine the current density of the four materials. An example will illustrate the significance of this criteria. 120
109.6
111
TEMPERATURE CHANGE '∆T' (°C)
100 82.2
78.4
80 60.8 55.7
60 43.3 36.7
40 18.2
38.1
24.9
18.7 13
20
0 0
11
22
33
44
55
66
77
CURRENT (A)
Fig.-1: Current Density Determining Chart Experimental Data: 1. The area of cross-section of PB strip used is (3 X 0.8) 2.4 mm2. 2. The area of cross-section of Steel, Brass and ETP-Copper strip used is (3 X 1) 3 mm2. 3. Experiment was performed at ambient temperature but the graph above considers the ‘ΔT’ at specific current. 4. The experiment is carried out for a particular current till the temperature saturates as shown in Figure 2.
Fig.-2: Saturation of Temperature for ETP Cu at 33A
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e-ISSN: 2582-5208 International Research Journal of Modernization in Engineering Technology and Science Volume:02/Issue:12/December -2020
Impact Factor- 5.354
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Application of Current Density determining Chart: A researcher wants to calculate maximum current carrying Capacity of a specimen having area of Cross-section 4mm2 as shown in figure 3 & Material is ETP-Copper. Maximum Temperature change allowed is 30°C
Fig.-3: Specimen From Figure 1 we shall determine the Current Density for the ETP-Cu as per the ΔT = 30°C
30
50 Here, for the ΔT = 30°C the allowable current is 50A. The ETP-Cu strip use for the experiment is 3mm2. Therefore, Current Density (J) = 50/3 = 16.7A/mm2. Now, the maximum Current (I) = J X A = 16.7 X 4 = 66.7A So, Maximum current that can pass through the ETP-Cu with 4mm2 Cross-section is 66.7A with a ΔT = 30°C.
IV.
RESULTS AND DISCUSSION
The graph plotted can be used to determine the Current Density of the four material for temperature rise between 15< ΔT≥110. Table 1 Shows the current density for ΔT = 30°C. Table-1: Current Density @ ΔT = 30°C SN.
Material
Current Density (J) A/mm2
1
ETP-Cu
16.7
2
Brass
9.1
3
Phosphor Bronze
5.4
4
Steel
-
Thus the criteiria to select a conductor is based upon the allowed temperature rise in the system and can vary as per the systems requirement. For Example in a system Melting point a thermoplastic is 100°C. Than as an industrial designer must allow temperature rise (ΔT) of 40°C as ambient temperature (T) = 50°C. As Total temperature = 90°C (ΔT+T). To avoid failure of system.
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e-ISSN: 2582-5208 International Research Journal of Modernization in Engineering Technology and Science Volume:02/Issue:12/December -2020
Impact Factor- 5.354
V.
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CONCLUSION
Based on the investigation, this article studies about criteria to decide the Current Density of conducting materials in Automobile Industry. Ultimately contributing to more robust product design. The following conclusion we derive from the analysis: 1. 2. 3. 4.
At a particular current the conductor temperature rises initially but after certain it saturates. The criteria to calculate current density is how much Temperature rise is allowed in a system for robust design. Further a conductorâ&#x20AC;&#x2122;s current density cannot be constant but can be defined as per the requirement. Phosphorus Bronze has more Copper content than Brass but still is less conductive. As Phosphorus is often used to deoxidize copper, which can increase the hardness and strength, but severely affect the conductivity. Silicon can be used instead of phosphorus to deoxidize copper when conductivity is important.
VI.
REFERENCES
[1]
www.bluesea.com/resources/108/Electrical_Conductivity_of_Materials
[2]
By David| February 11th, 2017|Categories: Electrometallurgy, Refining Tags: 906|Comments Off on Factors Affecting Copper Electrical Conductivity: Effect of Impurities
[3]
For materials Bureau of Indian Standard-Government Ministry IS 1897, IS 410, IS 7814 & IS 513.
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