Rotational motion testing service

Rotational Motion Testing Service – Comprehensive Evaluation of Torque, Speed, Efficiency and Mechanical Performance of Rotating Machinery and Components

As an ISO/IEC 17025 accredited independent testing laboratory, we offer specialised rotational motion testing services to manufacturers, engineering contractors, and quality assurance teams across the automotive, aerospace, power generation, marine, industrial equipment, and consumer goods sectors. Rotational motion – the angular displacement, velocity, and acceleration of rotating components – is a fundamental performance parameter for a vast range of products, from electric motors and gearboxes to shafts, couplings, bearings, turbines, and fans. Accurate characterisation of rotational motion parameters (torque, speed, power, efficiency, vibration, and torsional vibration) is essential for ensuring the reliability, efficiency, and safety of rotating machinery under both steady‑state and transient operating conditions. Our test platform combines high‑precision torque transducers, speed encoders, vibration analysers, and thermal monitoring systems to deliver comprehensive rotational performance data under controlled and simulated service conditions. All methods are aligned with ISO, IEC, SAE, ASTM, and GB/T standards, including ISO 1918 (Measurement of torque on rotating shafts), ISO 1940‑1 (Mechanical vibration – Balance quality requirements), IEC 60034‑2‑1 (Rotating electrical machines – Efficiency measurement), SAE J1349 (Engine power test code), ASTM E1876 (Dynamic Young's modulus), GB/T 15752 (Rotational motion testing), and GB/T 22036 (Dynamic testing of rotating machinery). Our inspection and test reports are recognised by the National Medical Products Administration (NMPA), the State Administration for Market Regulation (SAMR), the Ministry of Industry and Information Technology (MIIT), and international certification bodies for product registration, type approval, and quality assurance.

Rotating Machinery and Components We Regularly Test

Our rotational motion test facilities accommodate a wide range of rotating machinery, components, and assemblies. Typical test articles include:

Electric motors and generators – AC induction motors, synchronous motors, DC motors, servo motors, and stepper motors
Internal combustion engines – automotive, marine, and industrial engines for power and torque characterisation
Gearboxes, transmissions and differentials – for automotive, industrial, and aerospace applications
Turbines – steam turbines, gas turbines, wind turbines, and turbochargers
Pumps, compressors and fans – centrifugal and positive displacement types
Shafts, couplings, and flexible drive systems – for power transmission and torsional vibration assessment
Bearings and bearing assemblies – ball bearings, roller bearings, plain bearings, and air bearings
Rotating electrical components – slip rings, resolvers, encoders, and tachometers
Flywheels and energy storage devices – for energy storage and smoothing of rotational motion
High‑speed and high‑precision spindles – for machine tool and precision engineering applications

Torque, Speed and Power Characterisation – Measuring the Core Rotational Parameters

Torque and speed measurement – ISO 1918 / ISO 1940‑1 / SAE J1349 – We use a high‑precision in‑line torque transducer (capacity 0.1‑100 000 N·m, accuracy ±0.1 %) and a high‑resolution speed encoder (resolution 0.001 RPM, accuracy ±0.01 %) to measure the torque and speed of the rotating component under a defined load condition. The torque transducer is installed between the test article and the load machine (dynamometer or brake). The speed encoder is attached to the shaft (or integrated into the torque transducer). The torque and speed are recorded simultaneously, and the power (in W or kW) is calculated from the torque and the rotational speed: P = ω × T, where ω is the angular velocity (in rad/s) and T is the torque (in N·m).
Torque pulsation and ripple measurement – for assessing the torque stability of variable‑speed drives – For applications with variable speed or variable load, we measure the torque pulsation (the variation of torque over a full revolution) and the torque ripple (the high‑frequency torque variation). The torque pulsation is measured using a high‑speed data acquisition system (sampling rate ≥ 1 kHz) and is reported as the peak‑to‑peak torque variation (in N·m) and the torque ripple factor (the ratio of the peak‑to‑peak variation to the average torque). A high torque ripple (> 5 %) indicates a problem with the motor control or the mechanical design.
Speed stability and speed regulation – for assessing the speed control performance – We measure the speed stability (the variation of speed over time) and the speed regulation (the change in speed as a function of load) by applying a step change in load and recording the speed response. The speed stability is expressed as the percentage speed variation (typically < 1 % for good speed control); the speed regulation is expressed as the percentage speed droop (typically 2‑5 % for droop‑controlled systems).
Power measurement – for assessing the mechanical power output – The mechanical power (in kW) is measured directly from the torque and the speed. The power is measured at multiple load points (typically 10‑20 points from zero load to full load) to generate a power curve (power vs. speed). The peak power and the power curve are used for performance evaluation and for compliance with the manufacturer's specification.
Efficiency measurement – for assessing the energy conversion efficiency of motors, generators, and engines – For electric motors, we measure the input power (electrical) and the output power (mechanical) to calculate the motor efficiency (η = P_out / P_in × 100 %). The efficiency is measured at multiple load points (typically 25 %, 50 %, 75 %, 100 %, and 125 % of the rated load) and the efficiency map is plotted. The test is performed in accordance with IEC 60034‑2‑1 (for motors) and ISO 14396 (for engines).

Rotational Speed and Acceleration Testing – Simulating Transient and Steady‑State Conditions

Start‑up and shut‑down testing – for assessing the transient performance – We record the speed, torque, and temperature during the start‑up phase (from zero speed to rated speed) and the shut‑down phase (from rated speed to zero speed). The acceleration time (the time to reach rated speed) and the deceleration time (the time to stop) are measured and compared to the specification.
Speed‑ramp testing – for assessing the performance during speed changes – We apply a defined speed‑ramp profile (e.g., 0‑1 000 RPM in 10 seconds, then 1 000‑2 000 RPM in 5 seconds) and measure the torque, speed, and power during the ramp. The test assesses the response of the control system to speed changes.
Overspeed testing – for assessing the mechanical integrity and safety margin – We accelerate the rotating component to a speed exceeding the rated maximum (typically 110‑120 % of the rated speed) and hold it at the overspeed for a specified time (typically 1‑5 minutes). The test assesses the mechanical strength of the rotor, the shaft, and the bearings. The test is performed in a protective enclosure and is followed by a visual and dimensional inspection.
Low‑speed and high‑speed testing – for assessing the performance across the entire speed range – We test the rotating component at low speed (e.g., 10 % of rated speed) and at high speed (e.g., 110 % of rated speed) to assess the performance at the extremes of the operating range.
Reversing and bi‑directional testing – for components that operate in both directions – For components that are capable of reversing (e.g., reversible pumps, servo drives), we test the performance in both the forward and the reverse direction, and we measure the torque and the speed in each direction.

Vibration and Torsional Vibration Analysis – Assessing the Dynamic Behaviour

Shaft vibration measurement – ISO 10816‑1 / GB/T 11348 – for assessing the vibration levels of the rotating shaft – We install accelerometers (or proximity probes) on the bearing housings (or on the shaft itself) to measure the vibration displacement, velocity, and acceleration. The vibration is measured in three orthogonal axes (radial and axial) at multiple speeds (from zero to rated speed). The vibration levels are compared to the alarm and trip limits (as defined in ISO 10816).
Torsional vibration measurement – ISO 14839 / GB/T 19843 – for assessing the torsional resonance of the shaft system – We install a torsional vibration transducer (or use a laser vibrometer) to measure the torsional vibration (angular displacement) of the shaft. The torsional vibration is measured at multiple speeds (from zero to rated speed) and the frequency spectrum is analysed to identify the torsional natural frequencies. The presence of torsional resonance (a coincidence between the excitation frequency and a natural frequency) is reported as a potential risk.
Modal analysis – for identifying the natural frequencies and mode shapes – ASTM E756 / ISO 7626 – We perform a modal analysis (using a hammer impact test or a shaker excitation) to determine the natural frequencies, damping ratios, and mode shapes of the rotating assembly. The modal data is used to validate finite element models and to identify potential resonance issues.
Bearing vibration analysis – for assessing the condition of the bearings – ISO 10816‑3 / GB/T 11348 – We measure the vibration at the bearing housings and analyse the vibration spectrum to identify bearing‑related defects (e.g., inner race defects, outer race defects, ball defects, or cage defects). The defect frequencies are calculated from the bearing geometry and the rotational speed, and the presence of peaks at the defect frequencies is reported as a bearing defect.
Unbalance measurement – ISO 1940‑1 / GB/T 9239 – for determining the rotor unbalance – We measure the rotor unbalance (the amount of unbalance, in g·mm, and the unbalance phase angle) using a balance machine. The unbalance is measured at the specified speed (typically the operating speed or the balancing speed). The measured unbalance is compared to the allowable unbalance (as defined in ISO 1940‑1).

Friction, Wear and Lubrication Performance Testing – Assessing the Condition of Rotating Interfaces

Friction torque measurement – for assessing the frictional losses in bearings and seals – We measure the friction torque (the torque required to overcome the friction in the bearings and the seals) at multiple speeds (from zero to rated speed). The friction torque is measured using a torque transducer (with the component running at a steady‑state speed) or by measuring the power loss at the no‑load condition.
Wear debris and oil analysis – for assessing the condition of the lubricant and the wear of the components – ASTM D7684 / ISO 4406 – We take oil samples from the lubricating oil sump (or from the oil line) and analyse the oil for the presence of wear debris (particle size and concentration), the water content, the acid number (AN), and the viscosity. The results are compared to the specified limits.
Lubrication effectiveness test – for assessing the oil film formation – For oil‑lubricated bearings, we measure the oil film thickness (using an eddy current probe or a capacitive probe) at various speeds and loads. The test assesses the effectiveness of the lubrication system in maintaining a stable oil film.
Seal leakage test – for assessing the integrity of shaft seals – We measure the leakage rate (in mL/min or drops/min) of the shaft seal at various speeds and pressures. The test is performed with the seal operating under the specified service conditions.

Environmental and Durability Testing – Simulating Service Conditions

Temperature‑conditioned rotational motion test – for assessing the effect of temperature on performance – We perform the rotational motion test at elevated temperatures (e.g., 60 °C, 85 °C, 150 °C) and at reduced temperatures (e.g., -20 °C, -40 °C) using a temperature‑controlled chamber. The test assesses the effect of temperature on the torque, speed, efficiency, and vibration levels.
Humidity‑conditioned rotational motion test – for assessing the effect of moisture on performance – We perform the rotational motion test in a high‑humidity environment (e.g., 95 % RH, 40 °C) to assess the effect of moisture on the electrical insulation, the bearings, and the lubrication.
Salt spray and corrosion testing – ASTM B117 / ISO 9227 / GB/T 10125 – For components used in coastal or marine environments, we perform a rotational motion test in a salt spray environment (5 % NaCl, 35 °C) for 240‑500 hours and then assess the torque, speed, and vibration levels.
Endurance and fatigue testing – for assessing the long‑term reliability of rotating components – We run the component at a specified speed and load for a specified number of cycles (typically 1 000‑10 000 hours) and monitor the torque, speed, vibration, and temperature at regular intervals. The test assesses the long‑term reliability of the rotating components and identifies any degradation in performance.

Data Analysis and Interpretation – Quantifying Rotational Performance

Torque‑speed curve – the primary output of the rotational motion test – We plot the torque (in N·m) versus the speed (in RPM) to generate the torque‑speed curve. The curve shows the maximum torque (peak torque) and the torque at the rated speed. The torque‑speed curve is used to characterise the performance of the motor or engine.
Power‑speed curve – for assessing the power output – We plot the power (in kW) versus the speed (in RPM) to generate the power‑speed curve. The curve shows the maximum power (peak power) and the power at the rated speed.
Efficiency map – for assessing the efficiency over the entire operating range – For electric motors and engines, we generate an efficiency map (a contour plot of efficiency as a function of speed and load). The efficiency map is used for optimising the control strategy and for selecting the operating point for maximum efficiency.
Statistical analysis – for batch‑to‑batch consistency – For multiple components, we report the mean torque, the mean power, the mean efficiency, and the standard deviation. A CV of < 5 % is considered excellent.

Regulatory Compliance and Product Certification – Supporting Industry Standards

Our rotational motion testing services are performed in accordance with the most widely used international and national standards. The most commonly requested include:

ISO 1918 – Measurement of torque on rotating shafts – the primary standard for torque measurement
ISO 1940‑1 – Mechanical vibration – Balance quality requirements for rotors in a constant (rigid) state – for rotor balancing
IEC 60034‑2‑1 – Rotating electrical machines – Part 2‑1: Standard methods for determining losses and efficiency from tests – for motor efficiency testing
SAE J1349 – Engine power test code – for engine power and torque measurement
ASTM E1876 – Standard Test Method for Dynamic Young's Modulus, Shear Modulus, and Poisson's Ratio by Impulse Excitation of Vibration – for material damping and dynamic properties
GB/T 15752 – Rotational motion testing – the Chinese national standard for rotational motion testing
GB/T 22036 – Dynamic testing of rotating machinery – the Chinese national standard for dynamic testing
ISO 10816‑1 – Mechanical vibration – Evaluation of machine vibration by measurements on non‑rotating parts – Part 1: General guidelines – for vibration evaluation

Report Acceptance and Regulatory Recognition

All rotational motion tests are conducted under our ISO/IEC 17025 accreditation, using calibrated torque transducers, speed encoders, and vibration analysers, all traceable to national and international reference standards. Our final test reports include: a complete description of the test article (type, specifications, manufacturer), the test method and conditions (speed range, load range, temperature, humidity), the measured parameters (torque, speed, power, efficiency, vibration levels, unbalance), the torque‑speed and power‑speed curves, a statistical summary (mean, standard deviation, coefficient of variation), and a clear pass/fail verdict against your specified acceptance criteria. These reports are accepted by the National Medical Products Administration (NMPA), the State Administration for Market Regulation (SAMR), the Ministry of Industry and Information Technology (MIIT), and international certification bodies for product registration, type approval, and quality assurance. Bilingual (English/Chinese) versions are available to facilitate submissions to domestic and international authorities and to support your global market access.