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Sugawara Labs SMT-2 Stepper Motor Torque Tester

Sugawara Laboratories Inc.
Type: Motor Test System, Torque Tester
Supplier / Manufacturer: Sugawara Laboratories Inc.
Model: SMT-2

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Automatic Pull-In and Pull-Out Torque Measurement for Stepper Motors

The Sugawara SMT-2 is a precision stepper motor torque tester designed for automatic measurement of pull-in torque and pull-out torque using a Prony braking method.

The tester applies load to the motor through a brake thread wound around a pulley on the motor shaft. Two force sensors detect thread tension, allowing motor torque to be calculated without coupling loss and with minimal influence from rotational inertia.

±1% Torque measurement accuracy within the selected torque range
16–50,000 Hz Programmable motor drive pulse-frequency range
0.2–50 N Eight available force sensor ratings for different torque ranges
<0.1 mN·m Micro-stepper torque measurement supported with the SS-R2N sensor set

When combined with the SMC-2 controller and an appropriate SS Series sensor set, the SMT-2 automatically determines step-out and evaluates pull-in and pull-out torque over the programmed operating-frequency range. Measurement results can be displayed and stored on a Windows PC.

Pull-In Torque Measurement

Automatically determines the maximum load torque at which the stepper motor can start and maintain synchronized rotation from the holding state.

Pull-Out Torque Measurement

Gradually increases load at the programmed operating frequency and records the torque immediately before step-out occurs.

Prony Braking Method

Applies load through a brake thread and pulley, avoiding coupling loss and reducing the influence of rotational inertia on torque measurement.

Wide Sensor Selection

Eight available sensor ratings from 0.2 N to 50 N provide flexible torque ranges for motors of different sizes and output levels.

Micro Stepper Motor Measurement

The supersensitive SS-R2N sensor set enables stable measurement of very low torque from miniature stepper motors, including lead-screw motors.

Automatic Step-Out Detection

The measurement system detects the characteristic torque fluctuation that occurs when synchronized motor rotation is lost.

Automatic Performance Graphs

Measurement results can be automatically plotted to visualize pull-in and pull-out torque characteristics across drive frequency.

PC-Based Operation

Measurement control, data display, graphing, and result storage are performed from a compatible Windows PC.

Stepper Motor Development Characterization of pull-in and pull-out torque across operating frequency for stepper motor design and validation.
Micro Stepper Motors Low-torque measurement of miniature stepper motors using the supersensitive SS-R2N sensor set.
Lead Screw Motors Torque evaluation of compact lead-screw stepper motors used in positioning and motion-control mechanisms.
Camera Mechanisms Evaluation of small stepper motors used in mechanisms such as network-camera positioning systems.
Printer & Scanner Motors Pull-in and pull-out torque characterization of small motors used for paper handling and positioning mechanisms.
Motor Quality Evaluation Repeatable comparison of torque-frequency characteristics during development and quality-control testing.

SMT-2 Specifications

Load Method Prony braking
Force Detection Head Ratings 0.2 / 0.5 / 1 / 2 / 5 / 10 / 20 / 50 N
Torque Measurement Accuracy Within ±1% of torque range
Maximum Allowable Sensor Load 200% of sensor rating
Drive Frequency Range 16–50,000 Hz
Motor Drive Signal Square wave, duty 1:1; TTL-level voltage signal or open-collector signal
Torque Analog Output 2 VDC at torque rating from SMC-2
Communication RS-232C
Power Requirement 100–120 VAC or 200–240 VAC, 50/60 Hz
Power Consumption 50 VA or less
SMT-2 Dimensions 450 × 200 × 370 mm
SMT-2 Weight 12 kg
SMC-2 Dimensions 430 × 132.6 × 360 mm
SMC-2 Weight 9 kg

SS Series Sensor Selection

Sensor Set Rated Force Typical Use
SS-R2N 0.2 N Ultra-low torque and micro stepper motors
SS-R5N 0.5 N Very small stepper motors
SS-1N 1 N Small stepper motors
SS-2N 2 N Small to medium stepper motors
SS-5N 5 N General-purpose torque measurement
SS-10N 10 N Medium-torque stepper motors
SS-20N 20 N Higher-torque stepper motors
SS-50N 50 N Highest torque range supported by the standard sensor lineup

Actual torque range depends on both the selected sensor set and the effective pulley radius. Select the sensor and pulley combination according to the expected motor torque and required measurement resolution.



System Configuration

The SMT-2 system combines the torque tester, SMC-2 controller, an SS Series sensor set, the motor under test, its motor driver, and PC-based measurement software.

A brake thread is wound around a pulley attached to the motor shaft. Force is measured on both sides of the thread, allowing motor torque to be determined from the tension difference and pulley radius. This Prony-brake arrangement minimizes additional mechanical loss in the torque measurement path.

SMT-2 Tester

Mechanical platform for mounting the motor, pulley, brake thread, and force-sensor assembly.

SMC-2 Controller

Controls the measurement sequence and supports motor drive, torque measurement, and step-out detection.

SS Series Sensor Set

Interchangeable force sensors allow the measurement range to be matched to the torque characteristics of the motor under test.

PC Measurement Software

Supports measurement control, torque-frequency graphing, data display, and result storage.