Modification of a Cone-Plate Viscometer for Direct Recording of Flow Curves

Abstract

Using a concentric‐cylinder rotational viscometer, Weltmann has shown that automatic recording of flow curves in accordance with a predetermined program is important in the study of materials whose flow properties are shear‐dependent and time‐dependent. When the flow of such materials as greases was studied using the Ferranti‐Shirley cone‐plate viscometer, advantages of small sample size, ease of loading with minimum deformation, and uniform shear rate across the sample were apparent. However, time‐dependent properties of the grease could not be adequately described from data obtained in manual operation of the cone‐plate viscometer. An automatic control device for shear rate acceleration of the cone‐plate viscometer has been designed so that flow curves can be obtained automatically using an X‐Y recorder. Flow curves of typical greases and other materials exhibiting non‐Newtonian and time‐dependent properties have been successfully obtained using this automatic control device. The cone‐plate viscometer as modified has distinct advantages for the study of non‐Newtonian and time‐dependent materials.