On a 20x5 rectangular right screw thread the screw made of Nylon 66 is exactly the same as the female thread made of Ck60 steel. The radial gaps of the two threads are all 0.1mm and the total thread height 2.7mm. As is common in all plastic threads, the screw has a slightly greater thread thickness, ie 2.51 mm instead of 2.5 mm with the hole. Considering the elasticity measures of the laminar material E1 = 3.2GPa and the steel E2 = 205GPa, calculate the torque required to screw and unscrew 7 coils from the thread. As a friction factor, consider 0.08 in all positions.