GAOTek Surface Roughness Tester with Wide Measuring Range

This surface roughness tester with wide measuring range is designed to test the ex-circle, flat surface, conical surface of all types of metals and non-metals.




GAOTek surface roughness tester with wide measuring range is designed to test the ex-circle, flat surface, conical surface of all types of metals and non-metals. It has four parameters Ra, Rz, Rt and Rq with large measuring range. It adopts a high speed DSP processor for data processing which gives high accuracy in measurement and computation speed. The battery provides less charging time and has long life. This device comes with pull aluminum mold design, durable, anti-electromagnetism interference with modern appearance. It is mainly used in production sites.

Key Features

  • Dot matrix OLED display
  • Supports common interface for charging and communication.
  • High Speed DSP chip for data processing and calculation.
  • Supports calibration function and simple operation
  • Two ways charging: Special charger or USB port
  • Sensor probe with protective door
  • Optimized electric circuit design with transducer structure-design, high integrate power, driver and display.
  • Select freely with Ra, Rz, Rq, Rt parameters.
  • Test can be performed in ex-circle, flat surface, conical surface and also test groove with length and width larger than 15 in × 1.18 in (80 mm × 30 mm).
  • Wide measuring range suitable for all materials
  • Measurements are highly accurate
  • Automatic shut down and low power consumption

Technical Specifications

Test parameter Ra, Rz, Rq, Rt (μm)
Test range Ra, Rq: 0.05 μm ~ 10.0 μm
Rz,  Rt: 0.1 μm ~ 50 μm
Sampling length 0.0098 in (0.25 mm), 0.0314 in (0.80 mm), 0.098 in (2.50 mm)
Evaluation length 0.049 in (1.25 mm), 0.157 in (4.0 mm)
Stroke length 0.236 in (6 mm)
Indicating accuracy 0.01
Indication error ± 15 %
Variability of indication <12 %
Transducer contacting pin round
diameter and angle
Pin Tip arc radius:10 μm (±1 μm)
Sensor needle static force and  its rate of change Static force ≤ 0.016 N

Rate of change :≤ 800 N/m

Groove Length and Width 3.15 in × 1.18 in (80 mm × 30 mm)
Temperature -4 °F ~ 104 °F (-20 °C ~ 40°C)
Relative humidity <90 % No vibration and coercity around
Battery 3.7 V lithium ion battery
Overall size 4.17 in × 2.75 in × 0.94 in (106 mm × 70 mm × 24 mm)
Weight 7.05 oz. (200 g)

Additional Information

Working Principle

When the pickup driven by a driver is making a linear uniform motion along the test surface, the contact stylus in perpendicular with the work surface is moving up and down on the work surface. Its motion is converted into electric signals, which are amplified, filtered and transformed into digital signals through A/D. The signals are then processed by the DSP into Ra and Rz values before displayed on the screen.

Name of Each Components

5.2 Switch on, Switch off

Press this button for second boot, after a voice of di, the device goes into measurement state. Measuring parameters and sampling length will keep the last time before the shutdown of the state.

Press this button for second shutdown. The instrument will go into the low consumption status. In 3 minutes, without pressing, the operating instruments will be turned off.

Selecting Parameter

Before measuring the user should set up these parameters such as Ra Rz Rq Rt, the appropriate sampling length and metric/ imperial conversion. Touch keys, choose the sampling length 0.0098 in (0.25 mm), 0.0314 in (0.80 mm), and 0.098 in (2.50 mm).

Long press  key 2 seconds for metric/imperial conversion.

Touch keys, chose the measurement parameters Ra, Rz, Rq, Rt.


When the parameters are set up and the cut-off samples length is decided, it will come to measurement. Point the Stylus mark to the measured area stably and then press the Start Key on the top to start measurement, liquid crystal display as “Waiting”. At this time, it will be invalid to press the start button.

After the “Waiting “disappeared with two “d.d”, the measurement has been finished, and the screen will show the measured value.


Before use, calibration should be done with the standard sample plate. For example, there is a standard sample plate pointed to 3.14.

In shutdown condition, Press the start button boots, as shown below, release the start button. The tester will enter the status of Calibration.

Press the Up Key and Down Key to adjust the displaying value to the value 3.14.

Put the instrument in the scribed line area. Sensor taxiing direction perpendicular to the scribed line of texture direction. Press the Start Key to exit the status of Calibration. Repeating multiple times of calibration could evidently improve precision. After measuring, the new standard sample plate value will be stored to the memory instead of the old one. At the meantime, shutdown and restore, the instrument start work normally. If the user has multi-reticle sample plate, he can choose suitable sample plate to calibrate the tester against his measuring range in common use. By this way, the tester’s precision can be improved greatly.

Battery Recharge

Plug the charger into the tester’s recharge socket and have the tester recharged together with the battery symbol lighting (if no lighting, plug it again). Three hours recharging-time is enough. Filled animation end.

Even in shutdown condition may also start charging interface display.

Daily Maintenance


  • Protect the tester from collision, violent shock, heavy dust, dampness, oil stain, and strong magnetic field etc.
  • Please switch off in time after each measurement to save the energy, and have the battery recharged promptly when necessary.
  • The sensor is the precision part of the tester and particular care should be taken of After each use, put on the protective sheath gently to avoid violent shock to the sensor.
  • Standard sample plate provided with the tester should be given special protection to avoid scratch that may make the calibration inaccurate.

Terminology Definition

  • Surface Roughness is the microcosmic geometric form on the work-piece surface composed by peak and valley with small interspaces.
  • Sample Length is the benchmark’s length used to be distinguished its surface roughness.
  • Evaluation Length is the necessary length for evaluating the roughness profile. It may include one or more sampling lengths.
  • Ra: Arithmetical Mean Deviation of the Profile is arithmetic mean value of the deviation of the profile within sampling length.
  • Rz: The maximum Height of Irregularities is the distance between maximum depth of the profile peaks and maximum depth of the profile valley within the sampling length.
  • Rq: Root-mean-square Deviation of Profile
  • Rq is the square root of the arithmetic mean of the squares of profile deviation (Yi) from mean within sampling length.
  • Rt: Total Peak-to-valley Height Rt is the sum of the height of the highest peak and the depth of the deepest valley over the evaluation length.


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