According to end geometry:
1) Flat end milling cutter
2) Flat bottom R angle end milling cutter
3) Ball end milling cutter
4) Indexable insert end milling cutter
The difference between cnc and computer gongs
General CNC machining generally refers to precision machining, CNC machining lathe, CNC machining milling machine, CNC machining boring milling machine, etc.
It can be seen that the relationship between computer gongs and CNC is very close. Computer gongs and CNC are actually the same thing, both called CNC machine tools, but different people in different places call them different. Numerical control machine tools, even if they adopt numerical control technology, or are equipped with numerical control systems. In terms of application, CNC machine tools are used to represent various operations (such as spindle speed change, loose workpiece, feed and withdraw, start and stop, tool selection, cutting fluid supply, etc.) and steps required in the processing process, as well as the relative displacement between tools and workpieces with digital codes. Digital information is sent to a special or general computer through the control medium, and the computer processes and calculates the input information, Sending various commands to control the servo system or other executive components of the machine tool is the way for the machine tool to automatically process the required parts.
NC machining is an advanced machining technology in today’s mechanical manufacturing, and it is an automatic machining method with high efficiency, high precision and high flexibility. It inputs the NC program of the workpiece to the machine tool, and under the control of these data, the machine tool automatically processes the workpiece that meets people’s wishes to create beautiful products. Numerical control processing technology can effectively solve such complex, precise and small batch changeable processing problems as molds, and fully meet the needs of modern production.
Arrangement principle of CNC processing sequence
The processing sequence shall be arranged according to the structure of the parts and the condition of the blanks, as well as the need for positioning and clamping, with the focus on ensuring that the rigidity of the workpiece is not damaged.
Generally, the sequence shall follow the following principles:
- The CNC processing of the previous process shall not affect the positioning and clamping of the next process, and the general machine tool processing process shall also be considered comprehensively.
- The internal shape and cavity processing procedure shall be carried out first, and then the external shape processing procedure shall be carried out.
- It is better to connect the CNC machining processes with the same positioning, clamping method or the same tool to reduce the number of repeated positioning, tool change and moving the pressing plate.
- For multiple processes carried out in the same installation, the process with little damage to the rigidity of the workpiece shall be arranged first.
Classification of CNC hardware surface processing
What are the common types of metal surface processing? According to the summary of our production experience for many years, it can be divided into several common processing methods: metal painting processing, electroplating, surface polishing processing and metal corrosion.
- Spray painting processing: now the hardware factory adopts spray painting processing when producing relatively large hardware products. Through spray painting processing, the hardware can be prevented from rusting, such as daily necessities, electrical enclosures, box type handicrafts, etc
- Electroplating: electroplating is also one of the most widely used processing technologies for hardware processing. Through modern process technology, the surface of hardware parts is electroplated to ensure that the products will not be mildewed and embroidered under long-term use. Common electroplating processes include screws, stamping parts, battery pieces, car parts, trinkets, etc,
- Surface polishing: surface polishing is generally a long-term method used in daily necessities. For example, we produce a comb, which is a metal part made by stamping. Then the edges and corners of the punched comb are very sharp. We need to polish the sharp parts of the edges and corners into a smooth face, so that the human body will not be damaged in the process of application.
The above are several common ways of metal surface processing.
CNC processing stage division stage
During the hardware processing, the production and processing stages of hardware processing are divided into the following stages:
(1) Ensure the processing quality of hardware accessories
During rough machining of hardware parts, the metal layer cut out is thick, the cutting force and tightening force are large, and the cutting temperature is high, which will cause large deformation. According to the processing stage, the processing error caused by rough processing can be corrected by semi finishing and finishing, so as to ensure the processing quality of parts.
(2) It is convenient to find the defects of hardware parts processing blanks in time
Various defects of the blank (such as porosity, sand inclusion and insufficient allowance of the casting) are found after rough machining, which is convenient for timely repair or scrapping to avoid unnecessary waste caused by further processing.
(3) Easy to arrange heat treatment process
After rough machining, stress relief heat treatment shall be arranged to eliminate internal stress. Before finishing, final heat treatment such as quenching shall be arranged. The deformation caused by heat treatment can be eliminated by finishing.
(4) Reasonable use of hardware accessories processing equipment
The rough machining allowance is large and the cutting amount is large. The machine tool with high power, good rigidity, high efficiency and low accuracy can be used. The precision machining has small cutting force and little damage to the machine tool. High precision machine tools are adopted. This gives full play to the respective characteristics of the equipment, which can not only improve productivity, but also prolong the use of precision equipment
Explanation of over cutting reasons of CNC machining parts
There are many reasons for over cutting of workpieces in CNC machining. If the workpieces are over cut, they can be processed after repair welding. If the workpieces are over cut, they can be directly scrapped. In particular, over cutting of workpieces during large-scale mold processing is the most troublesome thing. How to deal with it? Let me share with you the work experience summarized in CNC machining
Hardware processing
If the workpiece is over cut, it is caused by carelessness and forgetting to take the tool radius into account in the programming. If it is software programming, it may be caused by the centering of the selected tool rather than tangency. These two programming methods will lead to the workpiece over cut.
- There is also a fault in the selection of cutting tools. For example, a milling cutter with a diameter of 16mm is used in the program, but a milling cutter with a diameter of 20mm is used. Although the difference of 4mm is not large with the naked eye, all the machined parts will be smaller. This requires that you carefully check whether the tool diameter is reasonable before processing, and do not take chances.
- Another reason for over cutting of workpieces is the input error of workpiece coordinate system when zeroing. Remember to offset the radius value of a zero bar. The input error of tool compensation, tool length and tool radius compensation must be input correctly. If the input length of tool length is 0.5mm, the workpieces will be 0.5mm longer. Large workpieces cannot be used directly. Whether the tool radius compensation is positive or negative should also be considered before machining, If the tool is not directly cut, the workpiece will be over cut.
The above are the reasons for over cutting of several common machining parts. Other reasons include looseness of the spindle and low precision of the ball screw, which will cause over cutting in the machining process. After over cutting, check the reasons in time to prevent similar situations from happening again.
Causes of over cutting of CNC machining parts
There are many reasons for workpiece overcutting in CNC processing. If the workpiece is overcutted, it will be processed after repair welding, or it will be directly invalidated. In particular, if the workpiece is overcutted during large mold processing, let’s share with you the work experience summarized in CNC processing
Hardware processing
If the workpiece overcut is programmed manually, it is caused by forgetting to take the tool radius into account in the programming. If it is software programming, it may be the selected tool alignment rather than tangency. These two programming methods will lead to the workpiece overcut.
- There is also a fault in tool selection for over cutting of machined parts. For example, a milling cutter with a diameter of 16mm is used in the program, but the result is a milling cutter with a diameter of 20mm. Although the difference between 4mm and 4mm is not big to the naked eye, all the machined parts will become smaller. This requires carefully checking whether the tool diameter is reasonable before machining, and don’t take chances.
- Another reason for workpiece overcutting is that the workpiece coordinate system input is wrong when zeroing. Be sure to remember to offset the radius value of a zero bar. The input error of tool compensation, tool length and tool radius compensation must be input correctly. If the input length of tool length is 0.5mm, the workpiece will be 0.5mm more. For large workpieces, they can’t be used directly. Whether the tool radius compensation is positive or negative should also be considered before tool compensation, Otherwise, it will also lead to over cutting of the workpiece.
The above are the reasons for overcutting of several common machining parts. Others, such as loose spindle and low precision of ball screw, will cause overcutting in the machining process. After overcutting, check the reasons in time to prevent similar situations from happening again.
ken. tang@chengcg.com
How to improve surface finish in CNC machining
In terms of size, the parts meet the blueprint specifications, but the surface finish and overall appearance are not ideal? What should we do?
Consider the following options:
- Control chip: chip evacuation is the key factor to produce good surface finish. Control chip may be the first thing you should consider. If the produced chips come into contact with the workpiece during machining, or if you are re cutting the chips, it is likely to affect your surface finish in a negative way. Consider the possibility of changing the style of the chip breaker you are using to help disassemble the chip for better control.
Although using air and coolant is a good choice to control chip removal, pay attention to coolant. Avoid using coolant when cutting intermittently. Hot cracks on the cutting edge will occur Due to intermittent heating and rapid cooling of cutting edges And it can lead to premature blade failure, or at least start to affect your surface finish because of over stressed cutting edges and failure.
- Improve speed: This is especially true when using cemented carbide tools. Increasing the speed will ensure that the contact time between the material and the tool tip is shorter Therefore, the edge accumulation on the tool is reduced, which may lead to poor surface finish. Increasing the rake angle of the cutting tool also helps to reduce and control edge accumulation.
- Use the correct tip radius: a larger tip radius will be able to adapt to a faster speed. The insert can feed at about half of TNR per revolution and still produce good results. If you exceed this TNR to IPR ratio, the tool will create more “linear” surface finish than the glossy smooth surface you want. Therefore, the larger the TNR, the faster the feed speed it can accommodate and still produce the desired results. However, using a very large TNR can produce chatter – reduce cutting pressure – so be careful and consider the speed required to cut the material – use a TNR tool that meets your needs.
It is also worth mentioning that using a larger tip radius means that you must leave more material for completion. To ensure proper operation of the tool, you must set TNR equal to or greater than TNR in order to complete the removal of the tool.
When milling, try to use fillet or spherical end milling cutter instead of plane end milling cutter. Something with a rounded radius will give you a higher finish at sharp corners and will certainly help extend tool life.
- Try to insert the wiper: as far as possible. The wiper insert has a small flat area adjacent to the tip radius. When the tool is fed along the workpiece, this plane actually “wipes” the finish and helps eliminate the linear finish that may be encountered at a faster feed rate – this allows the use of a smaller TNR to help control chatter.
- Increase the lead angle of the tool. Higher lead angle and positive tilt blades produce better surface finish than tools with shallow cutting angles. For example, a face milling cutter with a 45 ° cutting angle will produce a better surface finish than a face milling cutter with a 90 ° cutting angle.
- Eliminate dwell and pause: every time the tool stops moving when it comes into contact with the surface of the part, it will leave traces. Change the process if necessary, but try to ensure that the tool never stops or hesitates during the cutting process.
ken. tang@chengcg.com
Machining and milling technology of CNC parts
Let’s take a look at CNC machining and milling technology!
- Feed line of precision CNC machining and milling plane parts: when milling plane mechanical parts, the side edge of end mill is usually selected for cutting. In order to reduce the tool receiving trace and ensure the appearance quality of parts, the cutting in and cutting out procedures of tools are carefully designed.
- In the machining process, when milling the surface, the cutting in and cutting out points of the cutter and milling cutter should cut in and cut out the surface of the part along the extension line of the part summary curve, rather than directly cutting in the part along the normal direction, so as to avoid scratches on the machined surface and ensure the general lubrication of the part.
- In the process of precision CNC machining and milling, if the inner generalization curve allows extension, it should be cut in and out along the tangent direction. If the inner generalization curve does not allow extension, the tool can only cut in and out along the normal direction of the inner generalization curve, and the cutting in and cutting out points are selected at the intersection of two or more elements of the generalization of mechanical parts. When a few internal elements are tangent without intersection, in order to avoid leaving a notch at the general corner when the tool compensation is cancelled, the cutting point of the tool should be far away from the corner.
The above is about the skills in the process of precision CNC machining and milling. For the machining of simple and complex precision parts, the CNC milling technology will be different, which can be based on the appropriate machining line.
ken. tang@chengcg.com
Precision parameter control of CNC machining
In the machining industry, the accuracy parameters of CNC machining are mainly the level that the specific geometric parameters (specification, shape and position) of CNC parts are consistent with the ideal geometric parameters. Learn the following parameters in detail:
In the process of machining mechanical parts and small batch parts, CNC machining accuracy usually includes three level parameters: specification accuracy, shape accuracy and position accuracy.
- Appearance specification parameters of CNC processing
The specific specification of the surface itself or the middle of the surface after machining of CNC parts is consistent with the middle of the ideal part specification. The ideal part processing specification refers to the median value of the specification indicated on the part drawing.
- Shape accuracy parameters of CNC machining
The specific shape of the machined surface of CNC parts is consistent with the ideal part surface shape. The ideal part surface shape refers to the definite surface geometry shape.
- Precision parameters of machining parts of CNC parts
After machining, the specific parts of each surface of CNC parts are consistent with the parts between the surfaces of ideal parts. The position between the surfaces of ideal parts refers to the certain position between the surfaces.
The above is the accuracy parameter control of CNC machining. For different shapes, shapes, simplicity and complexity, it is necessary to select appropriate machining process parameters to improve CNC machining efficiency and ensure the machining accuracy of parts.
ken. tang@chengcg.com
-
- CNC Machining
-
- CNC Machining
-
- CNC turned
-
- CNC Machining
-
- CNC Turning
-
- CNC Milling service