Is a father's expulsion of his son for not entering the desired specialization, and his subsequent failure to visit him, considered a severing of kinship ties, especially given that the father is hard-hearted and may hit the son, and is telephone communication with the mother considered maintaining kinship ties?

The child must obey his father in matters that are beneficial to the father and do not harm the child. However, if there is no benefit for the father in the matter, or if it results in harm to the child, then obedience is not obligatory. It is always better for the child to earn his father's pleasure whenever possible. A child abandoning his father and ceasing to visit him constitutes cutting off kinship ties and disobedience (disrespect). However, if visiting might lead to unbearable harm, then there is no sin in refraining from it, while still being obligated to maintain ties with the father through whatever means are possible. The definition of maintaining ties (silah) is determined by custom.