There are several parameters that have significant influence in metal forming process. One of the most important of them is friction coefficient. Friction can change the pattern of metal flow and the force needed for deformation. It is necessary to determine the friction coefficient to study the effect of friction on metal forming process. This study is concerned with numerical and experimental...

The two well-known numerical radius inequalities for the tensor product $$A \otimes B$$ acting on $${\mathbb {H}} {\mathbb {K}}$$ , where A and B are bounded linear operators defined complex Hilbert spaces $$ {K}},$$ respectively \frac{1}{2} \Vert A\Vert B\Vert \le w(A B) w(A)w(B) \min \{ w(A) w(B) \}. In this article, we develop new lower upper bounds $$w(A B)$$ of study equality conditions th...