Product Category
Form & Surface Roughness Measurement
Roundness/cylindricity testers, contour and form measuring systems, and Ra/Rz surface roughness testers from Mahr, Mitutoyo, Taylor Hobson, and Zeiss. New, Refurbished, Absolute Certified, or Surplus, for bearings, engine components, and machine tool building.
What is Form & Surface Roughness Measurement?
Form measurement quantifies how closely a manufactured feature matches its intended geometric shape — roundness, cylindricity, flatness, straightness — independent of size. Surface roughness (texture) measurement instead characterizes the fine-scale peaks and valleys left on a surface by the manufacturing process, reported as parameters such as Ra (arithmetic mean roughness) and Rz (mean peak-to-valley height). Both are essential where function depends on more than a single diameter or length: bearing races, seal journals, cylinder bores, and gears all rely on tight form and finish control to perform correctly and wear predictably.
Form & Surface Testers We Supply
Roundness & Cylindricity Testers
- Rotating spindle roundness testers: A precision air-bearing spindle rotates the part (or the probe arm) while a stylus tracks radial deviation, plotting a polar trace of out-of-roundness. Adding a Z-axis column enables cylindricity, coaxiality, and perpendicularity measurement along the part's length (e.g. Mitutoyo Roundtest, Taylor Hobson Talyrond).
Contour & Form Measuring Systems
- Contour tracers / form measuring instruments: A stylus traces a 2D profile of a complex shape — turbine blade edges, gear tooth flanks, cam profiles, radii, and angles — and compares the trace against the nominal CAD contour (Mahr MarSurf, Taylor Hobson Form Talysurf).
Surface Roughness Testers
- Portable/handheld roughness testers: Battery-powered gauges for quick shop-floor Ra/Rz checks directly on the machine or part (Mitutoyo Surftest SJ series, Mahr MarSurf PS).
- Bench-top / lab roughness testers: Higher-precision stationary units for full profile analysis, filtering, and parameter reporting to ISO 4287/25178 (Mahr MarSurf, Zeiss).
- Non-contact optical roughness systems: White-light interferometry or confocal microscopy for delicate or very fine-finish surfaces where a stylus would risk damage.
Accuracy & Specification Considerations
Roundness testers are specified primarily by spindle accuracy (the residual error of the reference rotation itself, often sub-0.02 µm on precision spindles), radial and axial measuring range, and stylus/tip type. Roughness testers are specified by traverse length, vertical range and resolution, stylus tip radius (typically 2 µm or 5 µm, per ISO 3274), and the filtering cut-off wavelength (λc) applied — the cut-off setting materially changes the reported Ra value, so matching it to your drawing callout matters as much as the instrument's raw resolution. Environmental vibration isolation is important for both instrument types, since they resolve features at the micron and sub-micron level.
Form & Surface Testing Brands We Supply
| Brand | Parent / Origin | Key Products | Typical Application |
|---|---|---|---|
| Mahr | Mahr GmbH, Germany | MarSurf (roughness/contour), MMQ (roundness) | Bearings, engine components, gauges |
| Mitutoyo | Mitutoyo Corporation, Japan | Roundtest, Formtracer, Surftest | General manufacturing, machine shops |
| Taylor Hobson | Ametek Inc., UK | Talyrond (roundness), Form Talysurf (contour) | Aerospace, turbine components, gears |
| Zeiss | Carl Zeiss AG, Germany | Surface & form measurement systems | Automotive, precision manufacturing |
Condition Tiers for Form & Surface Testers
Factory New
Latest spindle, stylus, and software technology direct from the manufacturer, with full OEM warranty.
Refurbished
Air bearing spindle serviced, stylus and arm mechanism inspected, drive motors and electronics function-tested against factory specification.
Absolute Certified
Full requalification using traceable master rounds and roughness reference specimens, with a calibration certificate issued at handover.
Surplus / As-Is
Decommissioned units sold as-is, mechanically functional but not requalified — a low-cost route to a second station or a stylus/parts source.
Frequently Asked Questions
What's the difference between a roundness tester and a CMM for checking circularity?
A CMM samples a limited number of discrete points around a circle and fits a best-fit circle to them, which is adequate for many tolerances but can under-report true form error if lobing or waviness falls between sampled points. A dedicated roundness tester rotates the part continuously against a precision reference spindle, capturing a dense, continuous polar trace — the correct tool when roundness, cylindricity, or lobing itself is the critical characteristic, such as on bearing races and seal journals.
Does the roughness cut-off (λc) setting affect the Ra value I get?
Yes, significantly. The cut-off wavelength filters out longer-wavelength waviness from the roughness result, so the same surface measured with different λc settings can report different Ra values. Always match the cut-off to the value specified on your drawing or the applicable ISO 4288/21920 default for the measured Ra range — our team can help confirm the correct setting for your specification.
Can a refurbished roundness tester still meet its original spindle accuracy spec?
In many cases yes, since the air-bearing spindle itself is a very stable, low-wear component when properly maintained — the more common wear items are the stylus arm mechanism, drive electronics, and column ways. For a documented guarantee against traceable master rounds, choose our Absolute Certified tier, which includes full requalification and a calibration certificate.