Precision workpiece roughness is in line with international standards (ISO), and the term surface roughness should be used for formal and rigorous expressions.
Surface roughness refers to the small spacing and small peaks and valleys of the machined surface. The distance (wave distance) between its two crests or two troughs is very small (below 1mm), which is a microscopic geometric shape error.
Specifically, it refers to the level of the tiny peaks and valleys Z and the distance S. Generally divided by S:
S＜1mm is the surface roughness
1≤S≤10mm is the waviness
S＞10mm is f shape
02. Factors forming surface roughness
Surface roughness is generally formed by the machining method used and other factors, such as the friction between the tool and the surface of the part during the machining, the plastic deformation of the surface layer metal when the chips are separated, and the high-frequency vibration in the process system, electrical machining The discharge pits and so on. Due to the difference in machining methods and workpiece materials, the depth, density, shape and texture of the traces left on the processed surface are different.
03. Evaluation basis for surface roughness
1) Sampling length
The unit length of each parameter, the sampling length is the length of a reference line for evaluating the surface roughness. Generally use 0.08mm, 0.25mm, 0.8mm, 2.5mm, 8mm as the reference length under the ISO1997 standard.
Selection of sampling length L and evaluation length Ln of Ra, Rz, Ry
2) Evaluation length
Consists of N reference lengths. The surface roughness of each part of the component surface cannot truly reflect the true roughness parameters on a reference length, but N sampling lengths are needed to evaluate the surface roughness. Under the ISO1997 standard, the evaluation length is generally N equal to 5.
3) Baseline
The baseline is the contour centerline used to evaluate the surface roughness parameters.
04. Surface roughness evaluation parameters
1) Height characteristic parameters
Ra contour arithmetic mean deviation: the arithmetic mean of the absolute value of the contour deviation within the sampling length (lr). In actual measurement, the more the number of measurement points, the more accurate Ra is.
Rz Maximum profile height: the distance between the top line of the profile peak and the bottom line of the valley.
In the commonly used range of amplitude parameters, Ra is preferred. Before 2006, there was also an evaluation parameter in the national standard, which was "the ten-point height of micro-roughness" represented by Rz, and the maximum height of the contour was represented by Ry. After 2006, the national standard canceled the ten-point height of micro-roughness and adopted Rz. Indicates the maximum height of the contour.
2) Spacing feature parameters
Rsm The average width of the contour element. Within the sampling length, the average value of the microscopic unevenness of the contour. The microscopic unevenness distance refers to the length of the contour peak and the adjacent contour valley on the midline. In the case of the same Ra value, the Rsm value is not necessarily the same, so the reflected texture will also be different. Surfaces that value texture usually pay attention to the two indicators of Ra and Rsm.
The Rmr shape characteristic parameter is expressed by the contour support length ratio, which is the ratio of the contour support length to the sampling length. The profile support length is the sum of the length of each section of the profile obtained by intercepting a straight line parallel to the center line and a distance of c from the top line of the profile within the sampling length.
05, VDI3400, Ra, Rmax comparison table
The Ra indicator is often used in actual domestic production; the Rmax indicator is commonly used in Japan, which is equivalent to the Rz indicator; the European and American countries often use the VDI3400 standard to indicate surface roughness. When doing European mold orders, the VDI indicator is often used, such as often heard from customers. "The surface of this product is made according to VDI30."
Keywords：Precision parts
What is the difference between precision cnc machining and sheet metal machining...
The density of magnesium and magnesium alloys is low, only 1.74g/cm3, which is t...
The accuracy of CNC machining center mainly includes geometric accuracy, positio...
In our precision CNC hardware machining, the machining allowance is too small to...
CNC turning is mainly used to make round parts and is also the first choice for ...
Computer numerical control CNC milling is generally a metal fabrication process;...
Magnesium parts are easily oxidized by air after CNC milling, so how should anti...
Aluminum precision parts machining technology are the most widely used non-ferro...
CNC machining is a process method for machining parts on a CNC machine tool, and...
How to improve the efficiency and quality of CNC machining ? This is a commonpla...
What does 7:24 in CNC MACHINING BT handle mean? What are the standards of BT, NT...
Ordinary CNC machining generally refers to precision machining, CNC machining la...
Various casting methods including sand casting magnesium alloy, metal casting ma...
In our precision parts machining industry, the most commonly used machining meth...
There are many kinds of aluminum parts processed by CNC machine tools, among whi...
Aluminum and aluminum alloy cnc machining can be divided into rolling, extrusion...
CNC machining operation specification, mainly divided into 10 parts of CNC machi...
Many previous production and CNC machining methods and machining equipment have ...
CNC machining, also known as CNC machine tool machining, refers to the machining...
Aluminum alloy precision parts have high strength, good plasticity, excellent el...
Many people want to know what is the process of aluminum machining? In fact, the...
Nowadays, there are more and more, and the machining of precision parts is the s...
During the welding process of aluminum plate, if the atmosphere is in direct con...
There are generally two processes for mirror aluminum machining. One is to polis...
When looking for aluminum alloy precision parts machining plants, we need to cho...
Aluminum alloy machining technology is obtained by adding other metal elements t...
magnesium and aluminum Comparison In terms of technology, the current production...
CNC machining is still one of the cost-effective methods of on-demand production...
What are the Precision parts cnc machining skills characteristics of precision m...
Generally, the traditional Magnesium micro-arc oxidation film of magnesium alloy...
magnesium Micro-arc oxidation is a new technology for in-situ growth of ceramic ...
CPCI Rugged Chassis Shell is a customized chassis of our company. It has sturdin...
ATR chassis case machining was drafted by the American Avionics Technical Commit...
Aluminum alloy welding heat input is easy to quickly lose to the base metal, and...
Break through the technical difficulties of magnesium alloy machining,This techn...
The CNC machining process of magnesium alloy must be operated continuously, and ...
3D printing is a new type of rapid prototyping technology that integrates cuttin...
Compared with the equivalent material manufacturing process 3D printing has many...
Many people want to know what the aluminum profile machining process is like? In...
In the investment Precision casting production process, the reason for the burrs...
The structural parts with magnesium alloy as the base material are mainly used i...
Cutting fluids are generally divided into two types: oil-based and water-based. ...
The connection parts of the aluminum alloy body frame structure are formed by ca...
Aluminum forming The internal high pressure forming technology is a new type of ...
The solid shell protects the board, power supply and storage equipment, and can ...
Aluminum alloy is obtained by adding other metal elements to metal aluminum to o...
Aluminum shells are various shells made of aluminum alloys. It is highly flexibl...
Magnesium alloys are more and more widely used in modern society. Due to their u...
A lathe is a machine tool that mainly uses a turning tool to turn a rotating wor...
Usually five-axis linkage refers to the linear interpolation movement of any 5 c...
Four-axis: Generally, when the workpiece is not positioned in space, there are s...
Welding, also known as welding, is a manufacturing process and technology for jo...
For mechanical precision machining of gears and shaft parts, it is necessary to ...
CNC machining center is an automatic processing equipment developed by CNC milli...
Castings obtained by casting methods are called castings. So do you know what th...
Three-axis machining is processed by linear feed axes X, Y, and Z. Used for gene...
Precision workpiece roughness is in line with international standards (ISO), and...
There are many Parts machining technology, and the types of workpieces to be pro...
The role of the Precision parts Roving frame is to guide the yarn, and then guid...
Today I will talk about the general inspection and maintenance methods when the ...
In the near future, this project, known as the first unmanned CNC machining fact...
How will the tension in Ukraine affect China's manufacturing industry? This art...
Under the COVID-19 pandemic, China's manufacturing industry has resumed work on...
CNC machining quotations include material costs, machine depreciation costs, lab...
Because of the differences in aluminum materials, different machining processes,...
Chinese precision machining plants are high-end in many fields and in the world....
Aluminum alloy has better physical and mechanical properties than pure aluminum,...
Now every step of the mobile phone we hold in our hands is inseparable from prec...
Precision machining in China，China's machining industry, which is gradually grow...
Aluminum alloy forging production technology has developed by leaps and bounds, ...
In 2020, my country's total casting production has reached 51.95 million tons, ...
CNC machining can be said to be a more popular machining method at present. Comp...
CNC machining is a method of controlling machine tool movement and machining pro...
manufacturing machining 4.0 development was first proposed by Universal Robots o...
The United States has put forward the concept of smart manufacturing, which is g...
In recent years, the equipment manufacturing industry has achieved rapid develop...
In German manufacturing, there is a very interesting and crucial point: don't b...
The quality of the finished parts directly affects the quality of the mold, and ...
How are many things in daily life made from small springs to large cars? In fact...
Magnesium alloys have always attracted designers due to their low density. In th...
For a military case, it is very important to have a solid appearance, but when w...
Latest news
What is the difference between precision cnc machining a ...
The density of magnesium and magnesium alloys is low, on ...
The accuracy of CNC machining center mainly includes geo ...
In our precision CNC hardware machining, the machining a ...
Latest cases
The advanced equipment of the receiver housing can guara ...
The CPCI reinforced chassis is made of high-quality alum ...
Scan! Add WhatsAPP
Scan! Add WeChat
English