c = clearance between die and punch = [r.sub.d] - [r.sub.p] [(dy).sub.1] = distance between upper surface of the blank element and blank holder [(dy).sub.2] = distance between lower surface of the blank element and die surface dy = distance maintained by blank element from both blank holder and die surface [[tau].sub.1] = shear stress acted by fluid on upper surface of the blank element [[tau].sub.2] = shear stress acted by fluid on lower surface of the blank element du = velocity of the blank element relative to blank holder and die surface [mu] = dynamic viscosity or absolute viscosity or Viscosity of fluid [[tau].sub.A] = 2 [tau], the total shear stress acting by the fluid on the blank element h = height of the gap = thickness of fluid Acknowledgement
The experimental stand used for measuring the rheological parameters of the lubricants is a cone and plate viscometer, which offers absolute viscosity determination with precise shear rate and shear stress information.
The company's relative viscometer is said to provide fast, accurate and precise analyis of dilute polymer solutions for relative, intrinsic, inherent, specific and absolute viscosity, as well as molecular weight.
High-shear viscosity data from capillary rheometers and low-shear data from dynamic rotational rheometers can be compared because they both measure "true" or absolute viscosity. That is not true of torque rheometers, which provide only a relative measure of viscosity through correlation with torque.