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An electrochemical machining (ECM) is to be used to cut a through hole into a 12 mm thick aluminium plate. The hole has a rectangular cross- section, 10 mm × 30 mm. The ECM operation will be accomplished in 2 minutes, with efficiency of 90%. Assuming specific removal rate for aluminium as 3.44 × 10–2 mm³/ (A s), the current (in A) required is _____ (correct to two decimal places).
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- 988
- 962
- 968.992
- 868
Correct Option: C
Volume of metal to be removed.
= (10 × 30) × 12 mm³ = 3600 mm³
Ideal energy required.
| = | = 104651.163 As. | |
| 3.44 × 10-2 mm³/as. |
| Actual energy required = | As. | |
| 120 |
= 116279.07 As.
Time is 2 min = 120 s
| ∴ Current = | = 968.992 A. | |
| 120 |
