Apparent Viscosity Analyzer at High Temperature And High Shear Rate

Balancing Flow and Film Formation with the Apparent Viscosity Analyzer at High Temperature and High Shear Rate

Introduction
In modern engines and transmissions, lubricants operate under high temperatures and intense shear rates, where apparent (kinematic) viscosity does not fully predict film‑forming capability. The Apparent Viscosity Analyzer at High Temperature and High Shear Rate from Changsha Friend Experimental Analysis Instrument Co., Ltd. measures viscosity under combined thermal and shear conditions, offering insight into boundary‑film stability.

Testing Principle
Building on ASTM D4683, the instrument uses a capillary or concentric‑cylinder viscometer housed in a programmable oven (up to 150 °C). A high‑shear rotor or piston applies shear rates from 1,000 s⁻¹ to 1,000,000 s⁻¹. Pressure drop or torque is recorded continuously; software calculates apparent viscosity (mPa·s) at each shear rate and temperature.

Technical Design Features

• High‑Shear Drive System: Brushless motor and precision gearbox maintain shear rates to within ±1 %.

• Temperature‑Controlled Oven: PID‑regulated heating provides uniform sample temperature within ±0.1 °C.

• Pressure and Torque Transducers: High‑resolution sensors capture transient and steady‑state resistance signals.

• Automated Sample Loading: A syringe module injects defined sample volumes (0.5–5 mL) into the measurement cell, reducing handling error.

• Data Visualization: Real‑time plots of viscosity vs. shear rate and temperature generate shear‑thinning curves for formulation analysis.

Key Applications

• Engine Oil R&D: Correlate high‑shear film strength with wear protection under hot‑start conditions.

• Transmission Fluid Testing: Optimize friction modifiers for shift‑quality performance at elevated temperatures.

• Industrial Gear Oils: Ensure proper film retention in heavy‑duty gearboxes under high load and temperature.

Best Practices

1. Sample Preparation: Degas at 80 °C for 30 minutes to remove air bubbles that can distort shear measurements.

2. Cell Cleaning: Flush the viscometer capillary or cylinder with solvent followed by test oil to prevent cross‑contamination.

3. Calibration: Verify shear‑rate accuracy using Newtonian standard oils at multiple points.

4. Shear History Control: Pre‑condition each sample with a low‑shear ramp to establish a consistent starting structure.