Leeb surface roughness testers for machined parts
A surface roughness tester measures the microscopic peaks and valleys on a finished surface and reports them as numbers such as Ra and Rz, in micrometres. A diamond-tipped stylus travels a few millimetres across the part, and the instrument turns that trace into a pass or fail against the finish on your drawing.
Ecotao supplies the Leeb range of portable roughness testers, the Leeb432, Leeb400 and Leeb451, together with the SSR100 pocket tester from our online store. Supplied from our Cape Town base across South Africa and neighbouring countries.
What the roughness parameters mean
Every reading comes from the same trace. The instrument filters out waviness and form using the selected cut-off length, then calculates each parameter from what remains. The four parameters that all of the testers on this page measure are below.
- RaArithmetic mean roughness. The average distance of the profile from its mean line. The most widely specified value on engineering drawings. It describes typical texture but smooths over isolated scratches.
- RzMean peak-to-valley height. The highest peak to the lowest valley, averaged over five sampling lengths. Reacts to burrs, chatter and tool marks that Ra hides.
- RqRoot-mean-square roughness. Like Ra but weighted toward larger deviations. Used in optics and in specifications written to older RMS conventions.
- RtTotal height of profile. The single largest peak-to-valley distance over the whole evaluation length. The strictest check for a deep scratch on a sealing face.
The Leeb432 adds nine more, including Rp and Rv (peak height and valley depth, useful for bearing and sealing faces), RSm (average spacing of profile elements) and Rmr (material ratio, which indicates how much of the surface carries load).
Surface roughness testers available from Ecotao
The three Leeb models are supplied to order; contact us for configuration and lead time. The SSR100 is listed on the Ecotao store.
Leeb432 Surface Roughness Tester
The most capable model in the Leeb roughness range, built for QC rooms and inspectors who need more than an Ra number. It calculates 13 parameters, draws the measured profile on its 128 × 64 dot-matrix display, and prints or sends results over USB. Four filter types (RC, PC-RC, Gauss and D-P) let you match the filter named in older or customer-specific specifications, and it complies with ISO, DIN, ANSI and JIS.
- ParametersRa, Ry, Rq, Rz, Rt, RSm, RS, Rp, Rv, R3z, RSk, Rmax, Rmr
- Resolution0.001 µm
- AccuracyWithin ±6%; repeatability under 6%
- Cut-off lengths0.25, 0.8 or 2.5 mm
- Evaluation length1.25, 4 or 5 mm
- MemoryMore than 100 sets of results and waveforms
- Battery3.7 V Li-ion; over 20 h continuous use
- Size / weight119 × 47 × 65 mm; 440 g
- Supplied withMain unit, standard sensor, multi-standard groove reference sample, power adapter
- OptionsMeasuring platform, printer, PC analysis software
Leeb400 Surface Roughness Tester
A 200 g metal-cased tester for quick checks at the machine. The metal housing shields the sensor from electromagnetic interference near motors and VFDs, and the OLED colour display stays readable at wide viewing angles in a bright workshop. It measures outer diameters, flat and conical surfaces, and grooves larger than 80 × 30 mm, which covers shafts, faces and most fixture work.
- ParametersRa, Rz, Rq, Rt
- Resolution0.01 µm
- AccuracyWithin ±8%; repeatability under 12%
- Cut-off lengths0.25, 0.8 or 2.5 mm
- Evaluation length1.25, 4 or 5 mm
- Tracing length6 mm
- StandardsISO, GB
- Power3.7 V Li-ion, charged via USB
- Weight200 g
Leeb451 Surface Roughness Tester
A pocket tester with the probe built into the body and a single measurement button, so operators with no metrology background can check a finish in seconds. The metal shell suits production lines and site work on large workpieces that cannot go to a lab. It reports the same four core parameters as the Leeb400 and follows ISO, DIN, ANSI and JIS.
- ParametersRa, Rz, Rq, Rt
- Resolution0.1 µm (as listed by Leeb)
- AccuracyWithin 15%; repeatability under 12%
- Cut-off lengths0.25, 0.8 or 2.5 mm
- Evaluation length1.25, 4 or 5 mm
- Tracing length6 mm
- Power3.7 V Li-ion
- Size106 × 70 × 24 mm
- Supplied withMain unit, standard sensor, multi-standard groove reference sample, power adapter
- OptionCalibration block
SSR100 Pocket Type Surface Roughness Tester
A die-drawn aluminium pocket tester with host and sensor in one unit, and the only model here with Bluetooth. Readings appear live in a mobile app and download from there, and PC software is included for reporting. It runs on a single AA battery, so a flat cell on site is an easy fix. Measures metal and non-metal machined surfaces.
- Ra, Rq range0.05 to 10.00 µm
- Rz, Rt range0.10 to 50.0 µm
- AccuracyIndication error within ±10%
- StylusPiezo sensor, 10 ± 1 µm tip, 90°
- Sample lengths0.25, 0.8 or 2.5 mm
- Evaluation length1.25 or 4 mm; stroke 5.6 mm at 1 mm/s
- Display / memory1.14″ IPS colour; 500 results
- PowerOne 1.5 V AA alkaline battery
- Size / weight73 × 28 × 62 mm; about 220 g
- Supplied withStorage box, calibration block, battery, manual
Leeb surface roughness tester comparison
Side by side, the main differences are the number of parameters, resolution, stated accuracy and how results leave the instrument.
← Scroll to see full table →
| Feature | Leeb432 | Leeb400 | Leeb451 | SSR100 |
|---|---|---|---|---|
| Parameters | 13 | 4 (Ra, Rz, Rq, Rt) | 4 (Ra, Rz, Rq, Rt) | 4 (Ra, Rq, Rz, Rt) |
| Measuring range | Ask Ecotao | Ask Ecotao | Ask Ecotao | Ra 0.05–10.00 µm; Rz 0.10–50.0 µm |
| Resolution | 0.001 µm | 0.01 µm | 0.1 µm | Ask Ecotao |
| Stated accuracy | Within ±6% | Within ±8% | Within 15% | Within ±10% |
| Cut-off / sample length | 0.25, 0.8, 2.5 mm | 0.25, 0.8, 2.5 mm | 0.25, 0.8, 2.5 mm | 0.25, 0.8, 2.5 mm |
| Evaluation length | 1.25, 4, 5 mm | 1.25, 4, 5 mm | 1.25, 4, 5 mm | 1.25, 4 mm |
| Filters | RC, PC-RC, Gauss, D-P | Ask Ecotao | Ask Ecotao | Ask Ecotao |
| Profile graph on screen | Yes | Ask Ecotao | Ask Ecotao | Ask Ecotao |
| Data output | USB to PC and printer | USB to PC | Ask Ecotao | Bluetooth app; PC software |
| Power | 3.7 V Li-ion | 3.7 V Li-ion | 3.7 V Li-ion | 1 × AA alkaline |
| Weight | 440 g | 200 g | Ask Ecotao | About 220 g |
| How to buy | Quotation | Quotation | Quotation | Ecotao store (backorder) |
"Ask Ecotao" means the manufacturer's listing does not state the value. We will confirm it with the configuration we quote.
How to choose a surface roughness tester
Work through these four questions in order. The first one usually decides the model.
1. Which parameters does the drawing call for?
If the drawing or customer specification only states Ra (or Ra and Rz), any of the four testers will do. If it calls for Rp, Rv, RSm, Rmr or Rmax, or names a specific filter, you need the Leeb432.
2. How fine is the finish?
Ground, honed and lapped surfaces often sit below Ra 0.4 µm. At that level, resolution and accuracy matter: the Leeb432 (0.001 µm, within ±6%) or the Leeb400 (0.01 µm, within ±8%) are the better choices. For turned and milled surfaces in the Ra 0.8 to 6.3 µm band, all four models are suitable.
3. Do you need records?
Audit trails and customer reports favour the Leeb432 (printer and PC) or the SSR100 (phone app and PC software). If the operator only needs a go/no-go check at the machine, the Leeb400 or Leeb451 is quicker.
4. Where will it be used?
On the production floor or on site, size and robustness count: the Leeb400 and Leeb451 have metal housings, and the SSR100 has an aluminium body and runs on an AA cell. For large or awkward parts, ask about the Leeb432 measuring platform.
Selecting the cut-off length (ISO 4288)
The cut-off separates roughness from waviness. Choose it from the Ra you expect, unless the drawing states one.
← Scroll to see full table →
| Expected Ra | Cut-off (sampling length) | Evaluation length (5 cut-offs) | Typical surfaces |
|---|---|---|---|
| Above 0.02 up to 0.1 µm | 0.25 mm | 1.25 mm | Lapped, polished, superfinished |
| Above 0.1 up to 2 µm | 0.8 mm | 4 mm | Ground, fine-turned, reamed, honed |
| Above 2 up to 10 µm | 2.5 mm | 12.5 mm | Rough-turned, milled, shaped |
A 12.5 mm evaluation length is longer than the stroke of these portable testers, which offer up to 5 mm. For rough surfaces in the 2.5 mm cut-off band, they measure over fewer cut-offs, which is standard practice for handheld instruments.
How to measure surface roughness with a portable tester
- Check calibration. Measure the reference specimen supplied with the tester. If the Ra reading is outside the tolerance printed on the specimen, run the calibration routine and measure again.
- Clean the surface. Remove coolant, oil, swarf and dust. A single chip under the stylus will spike Rz and Rt.
- Set the cut-off and parameter. Use the value on the drawing, or pick from the ISO 4288 table above.
- Position the stylus across the lay. Trace at right angles to the machining marks (across the turning grooves on a shaft, for example). Tracing along the lay gives readings that are far too low.
- Keep the instrument still. Rest it on the part or a stand so the body does not move while the stylus travels. On small parts, use a V-block or measuring platform.
- Take several readings. Measure at three or more positions and record the spread, not just one value. Surfaces are rarely uniform.
What surface roughness testers do in practice
Engine and drivetrain components
Crankshaft journals, camshafts, cylinder liners and piston bores need a controlled finish so the oil film forms properly. Too rough and they wear; too smooth and they do not hold oil. A tester confirms the finish after grinding or honing, before assembly.
Shaft and seal refurbishment
Pump, gearbox and conveyor shafts rebuilt in workshops supporting mining, sugar and paper mills must meet the Ra window set by the seal maker. Measuring before fitting a new lip seal prevents early leaks and repeat call-outs.
Machine tool setting and tool wear
A rising Ra on the same operation is often the first sign of a worn insert or a loose setup. Checking the first-off part and then sampling during the run catches it before a batch is scrapped.
Hydraulic and pneumatic parts
Cylinder rods, valve spools and fuel injector mating faces rely on fine finishes to seal. Rz and Rt flag single scratches that would let pressure bypass a seal, which Ra alone can miss.
Electronics and non-metal parts
Contact surfaces, switch couplings and semiconductor components, as well as plastics and ceramics, can all be measured. A stylus tester gives a number where a visual check or fingernail test cannot.
Incoming inspection
Verifying supplier parts against the finish on the purchase drawing, with a printed or downloaded record, settles disputes with numbers instead of opinions.
Surface roughness tester FAQ
What is a surface roughness tester?
A surface roughness tester (also called a profilometer or roughness gauge) drags a fine diamond-tipped stylus across a surface at a constant speed. The stylus rises and falls over the peaks and valleys, the sensor converts that movement into an electrical signal, and the instrument filters it and calculates roughness parameters such as Ra, Rz, Rq and Rt in micrometres.
What is the difference between Ra and Rz?
Ra is the arithmetic average of how far the profile departs from its mean line, so it describes typical texture and hides isolated defects. Rz is the average height from the highest peak to the lowest valley across five sampling lengths, so it reacts to scratches, burrs and tool marks. Rz is always larger than Ra on the same surface. Most drawings specify Ra; sealing, bearing and coating work often specifies Rz as well.
Which cut-off length should I select on a roughness tester?
For ordinary non-periodic machined surfaces, ISO 4288 links the cut-off to the expected Ra: 0.25 mm for Ra above 0.02 up to 0.1 µm, 0.8 mm for Ra above 0.1 up to 2 µm, and 2.5 mm for Ra above 2 up to 10 µm. The evaluation length is normally five cut-offs, so 0.8 mm gives 4 mm. If the drawing states a cut-off, use that value.
Which Leeb surface roughness tester should I choose?
Choose the Leeb432 when you need more than the four basic parameters, a profile graph, printed reports or the tightest stated accuracy (within ±6%). Choose the Leeb400 for fast Ra, Rz, Rq and Rt checks on the shop floor with 0.01 µm resolution in a 200 g unit. Choose the Leeb451 for simple one-button checks with a built-in probe. Ecotao can confirm configurations and lead times for each model.
Can a portable roughness tester measure blast profile before painting?
ISO 8503-4 does describe a stylus method for blast-cleaned steel, but blast profiles are often deeper than the Rz range of compact pocket testers. The SSR100, for example, reads Rz up to 50 µm. For coating inspection work, surface profile comparators, replica tape or a profile depth gauge are the more common tools. Check the expected profile depth against the instrument range before relying on a pocket tester.
How do I calibrate a surface roughness tester?
Measure the reference specimen supplied with the instrument and compare the reading to the Ra value marked on the specimen. If the reading is outside tolerance, use the tester's calibration function to adjust it, then measure again. Check calibration at the start of each shift, after the stylus is changed or knocked, and whenever readings look inconsistent.
Where can I buy a Leeb surface roughness tester in South Africa?
Ecotao supplies Leeb surface roughness testers from its Cape Town base in Plattekloof, with delivery throughout South Africa, Namibia, Botswana, Zimbabwe, Mozambique, Lesotho and Eswatini. Contact sales@ecotao.co.za or +27 21 911 5835 for a quotation and lead time.
Get a quotation on a Leeb roughness tester
Tell us the part, the finish on the drawing and how you need to record results, and we will recommend a model and confirm the lead time. Delivery throughout South Africa, Namibia, Botswana, Zimbabwe, Mozambique, Lesotho and Eswatini.
- Zak: 086 142 8716
- Zaid: 082 390 3989
- Email: sales@ecotao.co.za · aqua@ecotao.co.za