Stylus Surface Roughness Tester

What is the Stylus Surface Roughness Tester?

A portable instrument that drags a diamond stylus across a surface to measure roughness parameters such as Ra, Rz and Rq. It is the right choice for verifying machined, ground or polished surface finish against drawing requirements.

Overview

A stylus roughness tester moves a diamond tip of 2 or 5 micrometer radius across the surface at a constant speed, typically 0.5 mm/s, while an inductive or piezoelectric pickup records vertical displacement. The signal is filtered with a Gaussian filter at a defined cut-off, usually 0.8 mm, to separate roughness from waviness, and parameters such as Ra, Rz, Rq and Rt are calculated over an evaluation length of five sampling lengths. Typical vertical range is 160 to 350 micrometers with 0.01 micrometer resolution. Portable units weigh a few hundred grams and can measure on the shop floor, inside bores with special pickups, and on flat or cylindrical parts. Accuracy depends on calibration with a roughness specimen of known Ra and on a clean stylus.

How does it work?

Inspection instruments convert a physical feature of a part into a number or an image that can be compared with a tolerance. Optical instruments magnify and project the silhouette or surface onto a screen or camera and measure distances using calibrated scales or pixel calibration. Eddy current and magnetic induction gauges measure the change in a probe's field caused by a coating over metal. Ultrasonic flaw detectors send high-frequency sound into a material and display echoes from boundaries and discontinuities, locating defects by time of flight. Stylus profilometers drag a fine diamond tip across a surface to record vertical displacement as roughness. Accuracy depends on calibration with traceable standards such as gauge blocks, step standards and foil references, on temperature stability and on operator technique.

What are the key features?

• Diamond stylus with 2 micrometer tip radius resolves fine machined and ground surfaces.
• Gaussian filter and selectable cut-off follow ISO 4288 and ISO 16610 requirements.
• Multiple parameters including Ra, Rz, Rq, Rt and Rsm are displayed in one trace.
• Portable body with rechargeable battery allows measurement directly on the shop floor.
• Built-in memory and printer output document results for each batch.
• Interchangeable pickups and supports measure bores, grooves and curved surfaces.

What are the technical specifications?

A typical stylus surface roughness tester configuration offers measuring range (Z) of ±80 μm (160 μm total), resolution of 0.01 μm, ra display range of 0.005–16 μm, stylus tip radius of 2 μm, stylus force of ≤4 mN and traverse length of ≈17.5 mm. Values are indicative of the product class; the exact figures for each configuration are confirmed on the quotation and the calibration documents supplied with the instrument.

Which applications is it used for?

The Stylus Surface Roughness Tester is used in machined shaft and bore finish, ground and polished component control, sealing surface verification and turned and milled part inspection. Across the wider Inspection Instruments class, laboratories also deploy it for dimensional inspection of machined parts, paint and plating thickness verification and weld and casting flaw detection.

Which standards and certifications apply?

Relevant standards and methods include ISO 2178, ISO 2808, ISO 4287, ISO 9712, ASTM E114, ISO 10360-1 and ASTM D7091. Certification candidates for this model are CE, ISO 9001 manufacturing and GB/T 19001; each is to be confirmed for the specific configuration before shipment, and certificates are supplied only where they have been issued.

Keep inspection instruments in a temperature-controlled area when tolerances are tight, since thermal expansion affects dimensional results. Calibrate with traceable reference standards appropriate to each instrument, such as gauge blocks, coating foils, calibration blocks for ultrasonic testing and roughness specimens. Verify zero and span before each shift. Protect optics, probes and styli from damage, and store them in cases. Operators of ultrasonic equipment should be qualified to recognized levels such as ISO 9712. Document inspection procedures, acceptance criteria and measurement uncertainty, and keep records for customer audits. Schedule periodic recalibration at intervals defined in the quality system.

How do I select the right Stylus Surface Roughness Tester?

Choose a portable stylus tester for shop floor roughness checks of Ra and Rz on metal parts. Choose an optical or contour system for very soft, delicate or three-dimensional surface analysis. In an RFQ specify parameters and standards, Ra range, stylus radius, part geometry, pickup accessories and whether printouts or software export are needed.

How does it compare with other Inspection Instruments variants?

Choose by the feature to be verified. Use a profile projector or video measuring machine for two-dimensional outlines, holes and small parts. Use a coating thickness gauge for paint, plating or anodizing, selecting magnetic induction for steel substrates and eddy current for non-ferrous metals. Use an ultrasonic flaw detector for internal defects in welds, castings and forgings. Use a roughness tester when surface finish is specified in Ra or Rz. Compare measuring range, resolution, accuracy relative to tolerance, probe or objective options, and software for programs and reports. A good rule is that the instrument accuracy should be one tenth of the tolerance. Consider operator skill, since ultrasonic and manual optical methods depend strongly on technique and training.