Rheology is the study of the effects experimented in a substance when a mechanical force is applied on a it (flow and deformation) under different external conditions. It is used to describe the consistency of different products and is normally defined by the components: viscosity and elasticity.
Measuring viscosity is determined by the tangible force required to displace the materials particles with a specific deformation-flow i.e. velocity.
The relationship between the tangible force and the deformation flow obtains the viscosity result. Ambient conditions such as temperature and pressure also have an effect on viscosity.
The measurement of viscosity is not just limited to the research laboratory, it has progressively entered the field of industrial quality control.
PRINCIPLES OF VISCOSITY
These instruments operate by means of a cylinder or disk (spindle) that is submerged into the material to be analysed and by measuring the resistance of the substance at a selected known speed. This resistance results is the measurement of the viscosity according to the flow characteristics of the reference spindle; the instrument calculates the result and directly displays the viscosity that is reported in cP (CGS) or mPa-s (SI).
A wide range of viscosity can be measured using viscometers that are equipped with different types of spindles and speed ranges. The design of the spindles and the principals of measurement principles are regulated by ISO 2555 and ISO 1652 standards. All spindles are made of AISI 316 stainless steel. Each spindle can be identified by a letter and a number.