Rotational Rheometer Geometry: Cone, Plate and Cylinder Need Their Own Rate Model

Identify the Deformation and Model

Brookfield’s primary manual distinguishes cone/plate and plate/plate rate factors, with plate/plate conversion depending on radius and gap. Rotor motion does not carry one universal shear-rate factor. Primary reference: geometry-dependent rate conversion.

Review a Hypothetical Comparison

For a hypothetical parallel-plate local model, rate is angular speed times radius divided by gap. At 1 rad/s, radius 0.010 m and gap 0.001 m give 10 per second at that radius. At radius 0.005 m the value is 5 per second. This spatial variation differs from the ideal small-angle cone model’s approximately uniform rate.

Keep the Evidence with the Decision

Record whether a plotted plate value is an edge rate, local rate or another reported convention. Keep radius, gap and angular-speed units with the calculation. For cone or cylinder results, request the applicable geometry relation and its assumptions, including truncation or narrow-gap approximations where relevant. Do not move a factor from one named fixture into another solely because RPM agrees.

The local calculation establishes no accepted geometry, maximum rate or material viscosity. Nonuniform rate also needs a suitable stress/viscosity interpretation rather than an arbitrary averaging rule. The useful output is a conversion-basis record for the actual report supplied to the equipment team. These invented dimensions are laboratory teaching inputs and specify no HM rotor or product-path clearance.

Which geometry-dependent shear-rate definition supports the comparison?

This blank worksheet is for your own project. It contains no H M machine trial result.

Customer Questions

Primary References

These references support the technical principles discussed in this guide. The worked examples and review questions are educational.

• Primary reference: geometry-dependent rate conversion
• Reference from hmpharmamachines.com