A helical compression spring, made of circular wire, is subjected to an axial force, which varies from 4 kN to 5.5 Kn. Over this range of force, the deflection of the spring should be approximately 6 mm. The spring index can be taken as 4. The spring has square and ground ends. The spring is made of patented and cold-drawn steel wire with ultimate tensile strength of 1180 N/mm2 and modulus of rigidity of 82140 N/mm2. The permissible shear stress for the spring wire should be taken as 40% of the ultimate tensile strength. Design the spring and calculate (i) wire diameter; (ii) mean coil diameter; (iii) number of active coils; (iv) total number of coils; (v) solid length of the spring; (vi) free length of the spring; (vii) required spring rate; and (viii) actual spring rate