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Surface Roughness Tester

The latest in state-of-the-art surface roughness testers, the SRG-4000 is designed with the shop environment in mind. These surface roughness testers are distinguished by a high level of accuracy, multiple parameters and simplicity of operation. Extremely sensitive and highly accurate readings from this Phase II surface roughness tester are offered via multiple surface roughness parameters, Ra, Rq(Rms), Rt and Rz.

The diamond stylus is hypersensitive and sophisticated enough to allow for a .001 (um) micron display resolution. The SRG-4000 surface roughness testers utilize an easy interface to allow for changes of in/mm (uin/um), cutoff length, sampling length, parameters, level of test(stylus position), digital filters and more! Measurement results are displayed as large characters on the LCD screen for easy recognition.

Battery powered portability allows the SRG-4000 surface roughness testers to mobilize productivity throughout the shop.

Optional accessories available for the SRG-4000 surface roughness testers include:
-2um Stylus
-Extension Rod
-NIST certified surface roughness standard


  • Menu driven operating system
  • 4 Different roughness parameters
  • Inside/Outside Diameters
  • Stylus position indicator
  • RS 232 output to printer/PC
  • Extended memory functions
Technical Specifications:
Roughness Parameters: Ra, Rz, Rq, Rt
Assessed Profiles Primary profile(p), Roughness profile(R) tp curve (Mr)
Conformance Standards: ISO/DIN/JIS/ANSI
Measuring System Metric μm,  Imperial μ inch
Display Resolution +/-20 μm  = 0.001 μm
+/-40 μm = 0.002 μm
+/-80 μm = 0.004 μm
Display Range Ra, Rq: 0.005 μm up to 16 μm
Rz, Rt: 0.02 μm up to 160 μm
Pick Up Measuring Range: +/- 80 μm
Sensor Specifications: 5 μm Diamond Tip Stylus
Sensor Angle: 90°
Contact Force: 4mN (0.4gf)
Display features Stylus position sensor
Battery level indicator
Direct display of parameters
Direct printing
Auto-off with auto store
Data output RS 232  to printer/PC
Cut-off lengths 0.25mm/0.8mm/2.5mm
Tracing length Lt 1.3mm – 17.5mm
Digital Filter RC, PC-RC, GUASSIAN, D-P
Detector Diamond tip radius 5 μm
Power Li-Ion battery
Working temperature 5-40 degrees C.
Dimensions 139mm x 56mm x 48mm
Weight 450g
Surface Roughness Tester Measurement Guide

Surface roughness, for purposes of this forum, is the result of some machining process and its effect on the material surface in question.

Skid type surface roughness testers are common instruments used on the shop floor. A diamond stylus is traversed across the specimen and a piezoelectric pickup records all vertical movement. Peaks and valleys are recorded and converted into a known value of a given parameter.

Parameters differ in how they approach looking at peaks and valleys. The most popular parameter is “Ra”. Ra is commonly defined as the arithmetic average roughness. While the Ra parameter is easy and efficient, there are other parameters that can be more specific and useful depending on the application requirements. It is the parameters that enable us to define surface roughness.

Today, for the purpose of checking Ra values, the use of portable, hand held, surface roughness testers are not only economical, but are digital and easy to use. These surface roughness testers are a given necessity for any shop floor that receives work with Ra requirements.

Surface Roughness Measurement Guide NIST Links
Surface Roughness Profile Parameters ASTM Links