Practical sharing | One article on roughness measurement-Nanjing Zhilian Optical Technology Co., Ltd

About Us

Certificates

Nanjing Zhilian Optical Technology Co., Ltd

E-mail
303924194@qq.com
Phone
13585156439
Address
Room 2302, Building 1, No. 5 Zhufeng Road, Zhuzhen Town, Liuhe District, Nanjing City

Practical sharing | One article on roughness measurement

Date: 2022-03-17Read: 0

Surface roughness（Surface roughness refers to the unevenness of small surface undulations (peaks, valleys) on the surface of a material.As early as 1920-1930, some researchers in Germany began studying surface roughness.Research has shown that the surface characteristics of materials have a significant impact on mechanical properties, and with the improvement of performance requirements and processing technology for mechanical components, the roughness of component surfaces has become particularly important.

The formation of roughness?

If you carefully observe the process of machining parts with a machine tool, you will notice that the surface of the part presents a complex shape under the action of the blade and the machine tool, which is mostly composed of a series of peaks and valleys of different heights, depths, and spacings. These peaks and valleys are very small, usually with a height difference of only a few tens of nanometers to a few micrometers.The size of roughness is mainly caused by the shape of the tool, feed rate, and rotational speed.In addition, due to the periodic vibrations generated by the machine tool during operation, periodic textures with slightly larger wavelengths, commonly known as waviness, will form on the surface of the product.

How to measure roughness?

Due to being a very microscopic parameter, roughness measurement was difficult in the early stages. In situations where roughness requirements were not high, roughness grades could usually be qualitatively evaluated by visual inspection, touch, or comparison with standard roughness samples. In the early days, quantitative analysis mainly used light cutting microscopes for measurement, but with the upgrading of measurement technology, this method has gradually been replaced. Now our measurement method isNeedle drawing method - contact typeorOptics - Non contactTwo main methods.

Needle drawing methodAs the name suggests, it is achieved by slowly tracing a fine needle with a precisely fixed needle tip shape and angle across the surface being measured. High precision sensors record the undulating movement trajectory of the needle tip, and then the micro profile of the surface being measured can be obtained for roughness evaluation. In order to increase the service life, the material of the needle tip is usually diamond.

Assessment of roughness?

The roughness parameter is different from some common length measurements. It does not directly measure the results, but analyzes and evaluates the contour curve of the material surface to ultimately obtain the roughness value we need.

Of course, the early roughness assessment standards were not unified, and each country and enterprise had their own set of standards. In order to facilitate mutual communication, the International Organization for Standardization (ISO) developed a set of standardsThe roughness standard and the unified calculation method for roughness parameters have been established.

The commonly used roughness parameters and calculation methods are as follows:

Average roughness value Ra-The arithmetic mean of the absolute values of the contour vertical axis

Root mean square roughness Rq-Root mean square average of roughness profile vertical axis

Average roughness depth Rz-The arithmetic mean of a single roughness depth Rzi over consecutive sampling lengths

Maximum roughness depth Rmax-Rmax is the maximum single roughness depth within the entire evaluation length

Average spacing RSm between contour elements-The arithmetic mean of the spacing between roughness contour elements

Core roughness depth Rk-Depth of roughness core contour

Minimum peak height Rpk-The average peak height generated by the roughness core contour

Minimum valley depth Rvk-The average valley depth generated by the roughness core contour

Mahr Company can provide customers with a full line roughness measurement solution ranging from portable to optical non-contact

Portable roughness meter

MarSurf Pocket Surf

MarSurf M 310

MarSurf M 400

Desktop roughness tester

MarSurf LD 260

MarSurf VD 280

Optical non-contact roughness measurement scheme

MarSurf CP select

MarSurf CM Explorer

Customized roughness measurement scheme

Measurement of inner hole roughness

If you have roughness measurement and testing needs, please contact Mahr's local sales or authorized dealer.