Turntables are key equipment for precision testing and automated production in fields such as aerospace, autonomous driving, and consumer electronics. Their performance directly determines testing accuracy and production efficiency. During the selection process, many users fall into the misconception that "the higher the parameters, the better," leading to wasted costs or equipment mismatch with requirements. This article focuses on the three most crucial selection parameters for turntables— load , angular rate , and resolution —and provides a quantitative selection method based on application scenarios to help companies accurately match their needs.

I. Load Parameters: Load-bearing capacity determines equipment stability; it is by no means "the larger, the safer".

Load is the most fundamental selection criterion for turntables, directly affecting their structural strength, drive system lifespan, and operational stability. Here, "load" refers not only to the weight of the object being supported, but encompasses three core dimensions: static load , dynamic load , and eccentric load . All three must be met simultaneously; none can be omitted.

1. Static load: Calculated based on "actual load capacity + safety redundancy".

Static load refers to the maximum weight that the turntable can stably bear when stationary, and it serves as the benchmark for equipment structural design. When selecting a turntable, the actual weight of the workpiece to be tested/processed must first be determined, followed by the weight of fixtures, tooling, and other auxiliary components, ultimately reserving a 20% to 30% safety margin . For example, if the total weight of the workpiece and tooling is 80 kg, a turntable with a static load of at least 100-104 kg should be selected to avoid deformation of the mechanical structure due to long-term full-load operation.

Special note: The "maximum load" marked by some manufacturers is the instantaneous peak load. You need to confirm its "continuous working static load" parameter, which is the key indicator for long-term operation.

2. Dynamic load: Matching force transmission requirements under motion conditions.

When the turntable is in motion such as starting, accelerating, or decelerating, it generates inertial force, and the load requirement at this time is called dynamic load. Dynamic load is usually positively correlated with angular acceleration (rate of change of angular velocity), and the calculation formula can be simplified to: Dynamic load = Static load × (1 + angular acceleration × radius / gravitational acceleration) (applicable to low-speed to medium-speed scenarios).

In high-frequency motion scenarios such as automated production lines, neglecting dynamic load can easily lead to problems such as turntable start-stop jamming and decreased positioning accuracy. For example, for a certain electronic component testing turntable, the total weight of the workpiece is 50kg, the angular acceleration is 10rad/s², and the turntable's bearing radius is 0.2m. Therefore, the dynamic load is approximately 50×(1+10×0.2/9.8)≈60.2kg, and a model with a dynamic load ≥60.2kg should be selected.

3. Off-center Load: Solving the Hidden Risks of "Center of Gravity Shift"

If the workpiece's center of gravity does not coincide with the turntable's rotation center, an off-center load will be generated, leading to problems such as vibration and accelerated wear during turntable operation. When selecting a turntable, attention should be paid to the "maximum allowable off-center distance" parameter provided by the manufacturer. If the actual off-center distance exceeds the standard, a turntable with an off-center distance compensation structure should be selected, or the center of gravity position should be adjusted through tooling design.

Typical scenario: In the testing of aerospace components, the workpiece has an off-center distance of 50mm due to its irregular shape. In this case, it is necessary to select a turntable with an off-center load bearing capacity greater than or equal to the actual off-center torque to avoid distortion of test data.

II. Angular velocity: Dynamically matching "accuracy requirements" and "efficiency goals"

Angular velocity determines the operating efficiency of the turntable, but its selection must be based on the premise of "meeting accuracy requirements," rather than simply pursuing high speed. It is necessary to make a comprehensive judgment based on the "motion mode" of the application scenario (uniform motion/variable motion/intermittent motion), combined with three major indicators: maximum angular velocity , angular acceleration , and uniform motion accuracy.

1. Maximum angular velocity: Distinguish between "instantaneous peak value" and "continuous operating value"

The "maximum angular velocity" listed by manufacturers is often an instantaneous peak value, while in practical applications, the "continuous operating angular velocity" should be considered. For example, a certain lidar test turntable can reach a peak angular velocity of 300°/s, but if it exceeds 150°/s during continuous operation, the motor is prone to overheating. Therefore, it is necessary to select a suitable continuous angular velocity model based on the daily continuous working time (8 hours/12 hours).

Low-speed scenarios (<10°/s) : such as the inspection of precision optical components, priority should be given to ensuring angular velocity stability, and a turntable with a uniform velocity error ≤ ±0.1°/s should be selected;

Medium-speed scenarios (10°/s~100°/s) : such as automated assembly lines, it is necessary to balance efficiency and precision. Select models with angular acceleration ≥50°/s² to avoid excessive start-up and shutdown time.

High-speed scenarios (>100°/s) : For inertial navigation testing, attention should be paid to the dynamic balance level of the turntable (at least G4 level or above) to reduce vibration interference during high-speed rotation.

2. Angular acceleration: A key indicator affecting "response speed"

In intermittent motion scenarios (such as workpiece positioning and step-by-step testing), angular acceleration directly determines the turntable's response speed. For example, in a certain automotive sensor production line, the turntable needs to accelerate from rest to 50°/s within 0.5 seconds and then decelerate back to rest. The required angular acceleration is (50-0)/0.25 = 200°/s² (acceleration and deceleration each take 0.25 seconds). A turntable with an angular acceleration ≥ 200°/s² must be selected to ensure that the production cycle time meets the requirements.

3. Uniform speed accuracy: The "core threshold" for high-precision scenarios

In scenarios such as radar scanning and astronomical observation simulation, the uniform speed accuracy of the turntable directly affects the data acquisition quality. Uniform speed accuracy is usually expressed as "velocity fluctuation rate," which is the percentage of the maximum deviation between the actual angular velocity and the set angular velocity during operation. For example, if a radar test requires a uniform speed accuracy of ≤±0.05%, and the set angular velocity is 100°/s, then the actual angular velocity fluctuation needs to be controlled between 99.95°/s and 100.05°/s. In this case, a turntable using a servo motor and a high-precision encoder for closed-loop control should be selected.

III. Resolution: The "quantitative scale" of accuracy must be closely matched with the "measurement requirements".

The resolution of a turntable is divided into angular position measurement resolution and angular position control resolution . The former reflects the minimum rotation angle that the turntable can achieve, while the latter reflects the adjustment accuracy of the control system. The two must work together to meet application requirements and avoid increased costs caused by "excessive resolution".

1. Angular position measurement resolution: The selection criterion is based on the "smallest unit of measurement".

The resolution of angular position measurement is determined by the turntable's transmission mechanism (such as a harmonic reducer or ball screw) and the angular position measuring device (such as a photoelectric encoder or rotary transformer). When selecting a device, the "minimum angle measurement requirement" of the workpiece being tested must be clearly defined, and a 10% to 20% accuracy redundancy should be reserved.

2. Angular position control resolution: Avoiding a disconnect between "hardware precision" and "control precision".

Even if the angular position measurement resolution of the turntable meets the standard, high-precision positioning cannot be achieved if the control resolution of the control system is insufficient. Control resolution depends on the controller's computational accuracy and pulse equivalent. For example, a turntable using a 17-bit absolute encoder has a theoretical control resolution of...

360°/(2¹⁷) = 360°/131072 ≈ 0.0027°

It needs to be paired with a controller that supports 17-bit data processing to fully leverage the advantages of hardware precision.

3. The Coordination of Resolution and Angular Velocity: A Precision Balancing for High-Speed Scenarios

In high-speed operating scenarios, excessively high resolution can lead to response delays in the control system. Therefore, a balance must be found between resolution and angular velocity. For example, in a high-speed missile simulation test turntable with an angular velocity of 500°/s, choosing an ultra-high resolution of 0.0001° would require the controller to process 5,000,000 data points per second, easily causing lag. In this case, choosing a resolution of 0.001° satisfies both the testing accuracy requirements and ensures stable system operation.

IV. The Logic of Coordinated Selection of Three Major Parameters and Techniques for Avoiding Pitfalls

The load, angular velocity, and resolution of a turntable are not independent but interrelated and mutually restrictive. For example, increasing the load will reduce the turntable's maximum angular velocity and accuracy; increasing the resolution may limit high-speed performance. Therefore, selection should follow the principle of "demand first, coordinated matching," avoiding the following common misconceptions:

1. Tips to avoid pitfalls: Avoid "parameter stacking" and focus on "actual needs".

Some users blindly pursue "maximum load," "highest angular velocity," and "highest resolution," leading to a 30% to 50% increase in equipment procurement costs, while only 50% of the performance is actually used. The correct approach is to first clarify the core requirements (e.g., prioritize resolution for precision testing, and prioritize angular velocity and load for production lines), and then select parameters based on those requirements, rather than doing the reverse.

2. Verification method: Request the manufacturer to provide a "load characteristic curve".

Reputable manufacturers will provide load characteristic curves for their turntables, clearly indicating data such as the maximum angular velocity under different loads and the change in accuracy at different angular velocities. For example, a turntable may have a maximum angular velocity of 200°/s under a 50kg load, but the maximum angular velocity drops to 100°/s under a 100kg load. By observing the curves, one can intuitively determine whether the turntable matches their needs and avoid being misled by manufacturers' "single-parameter advertising."

V. Conclusion: The "Golden Formula" for Turntable Selection

Precise selection = Clearly define core requirements (accuracy/efficiency/load capacity) + Quantify three key parameters (20% load redundancy, angular velocity matching motion mode, resolution benchmarked against the smallest measurement unit) + Verify collaborative characteristics (load characteristic curve). Through the parameter analysis and selection logic presented in this article, enterprises can effectively avoid pitfalls and select a turntable that offers "performance matching and optimal cost," providing stable and reliable equipment support for production and testing.