If we purchase a machine by using loan from the bank, what is the treatment to the interest expenses regarding ias 23 borrowing cost?

IAS23 allows Capitalization of interest cost in case of Qualifying Asset, and Qualifying Asset defined by the IAS/IFRS is that asset which takes substantial time for completion. Ready made plant and Machinery does not qualify as Qualifying asset and such interest cost can not be made part of the machine unless the machine is a complete plant and requires substantial time for completion.

In your case the interest cost on the loan for purchase of machine shall be expensed out and can not be capitalised.

IAS23 allows to capitalize interest payment of loan obtained specifically for the purpose of acquiring a non-current asset. If you acquire a non-current asset from pool of financing than IAS23 allows interest payment to capitalize at weighted average rate.

If you obtain a loan for construction of building than IAS23 specifically state that capitalization should stop when construction process is being stopped for any reasons.