Waviness is the measurement of the more widely spaced component of surface texture. It is a broader view of roughness because it is more strictly defined as "the irregularities whose spacing is greater than the roughness sampling length". It can occur from machine or work

deflection Deflection or deflexion may refer to: Board games * Deflection (chess), a tactic that forces an opposing chess piece to leave a square * Khet (game), formerly ''Deflexion'', an Egyptian-themed chess-like game using lasers Mechanics * Deflection ...

s, chatter,

residual stress In materials science and solid mechanics, residual stresses are stresses that remain in a solid material after the original cause of the stresses has been removed. Residual stress may be desirable or undesirable. For example, laser peening i ...

vibration Vibration is a mechanical phenomenon whereby oscillations occur about an equilibrium point. The word comes from Latin ''vibrationem'' ("shaking, brandishing"). The oscillations may be periodic, such as the motion of a pendulum—or random, su ...

s, or

heat treatment Heat treating (or heat treatment) is a group of industrial process, industrial, thermal and metalworking, metalworking processes used to alter the physical property, physical, and sometimes chemical property, chemical, properties of a material. ...

.. Waviness should also be distinguished from flatness, both by its shorter spacing and its characteristic of being typically periodic in nature.

Parameters

There are several parameters for expressing waviness height, the most common being Wa & Wt, for ''average waviness'' and ''total waviness'', respectively. In the lateral direction along the surface, the ''waviness spacing'', Wsm, is another parameter that describes the mean spacing between periodic waviness peaks. There are numerous measurement settings which influence these resultant parameter values, which are mentioned below. One of the most important is the ''waviness evaluation length'', which is the length in which the waviness parameters are determined. Within this length the ''waviness profile'' is determined. This is a surface texture profile that has the shorter roughness characteristics filtered out, or removed; it also does not include any profile changes due to changes in workpiece geometry that are either unintentional (flatness) or intentional (form). Waviness is included in the

ISO standards The International Organization for Standardization (ISO ) is an international standard development organization composed of representatives from the national standards organizations of member countries. Membership requirements are given in A ...

ISO 4287ISO 4287
Geometrical Product Specifications (GPS) -- Surface texture: Profile method -- Terms, definitions and surface texture parameters and ISO 16610-21ISO 16610
Geometrical product specifications (GPS) -- Filtration -- Part 21: Linear profile filters: Gaussian filters as well as the U.S. standard ASME B46.1,ASME B46.1
Surface Texture (Surface Roughness, Waviness, and Lay). and it is part of the

surface texture symbol Surface finish, also known as surface texture or surface topography, is the nature of a surface as defined by the three characteristics of lay, surface roughness, and waviness.. It comprises the small, local deviations of a surface from the perf ...

used in

engineering drawing An engineering drawing is a type of technical drawing that is used to convey information about an object. A common use is to specify the geometry necessary for the construction of a component and is called a detail drawing. Usually, a number o ...

Measurement

The measurement of the waviness can be done with a variety of instruments, including both surface finish profilometers and roundness instruments. The nature of these instruments is continually progressing and now includes both stylus-based contact instruments as well as optical & laser-based non-contact instruments. In earlier instruments, the measurement output was inherently linked to the instrument itself, whereas there is now emerging some divergence between the instrument that collects the surface profile data and the analytical software that is able to evaluate this data. Examples of two earlier generation instruments are the waveometer or a microtopographer. A waveometer uses a plastic tip that is connected to an electronic pickup which then measures the surface variations. The measurement is recorded as an electronic signal which is amplified and split into two signals: a high band and a low band. For measuring a

ball bearing A ball bearing is a type of rolling-element bearing that uses balls to maintain the separation between the bearing races. The purpose of a ball bearing is to reduce rotational friction and support radial and axial loads. It achieves this ...

, the low band signal records variations that occur every four to seventeen times per revolution and the high band signal records variations that occur seventeen to 330 times per revolution; the low band is the waviness. These bands are transmitted to an

oscilloscope An oscilloscope (informally a scope) is a type of electronic test instrument that graphically displays varying electrical voltages as a two-dimensional plot of one or more signals as a function of time. The main purposes are to display repetiti ...

for analysis.

Use

Waviness measurements are not as common as roughness measurement however there are important applications. For example, waviness in bearing balls and bearing races is one of the reasons for vibrations and noise in ball bearings. Other application examples are waviness in flat milled sealing surfaces, "orange peel" on painted surfaces, and chatter on round shaft surfaces.

External links

Surface Metrology Guide

Related standards

* ANSI/ASME B46.1 *

ISO 4287 ISO is the most common abbreviation for the International Organization for Standardization. ISO or Iso may also refer to: Business and finance * Iso (supermarket), a chain of Danish supermarkets incorporated into the SuperBest chain in 2007 * Is ...

References

Bibliography

*. *. *{{Citation, last1 = Oberg, first1 = Erik, last2 = Jones, first2 = Franklin D., last3 = Horton, first3 = Holbrook L., last4 = Ryffel, first4 = Henry H., title =

Machinery's Handbook ''Machinery's Handbook'' ''for machine shop and drafting-room; a reference book on machine design and shop practice for the mechanical engineer, draftsman, toolmaker, and machinist'' (the full title of the 1st edition) is a classic reference ...

, place = New York, publisher = Industrial Press Inc., year = 2000, edition = 26th, isbn = 0-8311-2635-3. Engineering mechanics Materials science de:Welligkeit fr:Cambrure