April 2021 – Page 2 – CNC Machining & Turning, Milling, Metal parts

Milling technology in precision CNC machining

In the field of machining industry, precision CNC parts processing is widely involved in the industry. Let’s take a look at CNC milling technology!

Feeding circuit of precision CNC milling plane parts: when milling plane mechanical parts, the side edge of end mill is usually used for cutting. In order to reduce the tool trace and ensure the appearance quality of the parts, the cutting in and cutting out procedures are carefully designed.
In the process of machining, when milling the surface, the cutting in and cutting out points of the cutter should cut in and cut out the surface of the part along the extension line of the part outline curve, instead of cutting directly into the part along the normal direction, so as to avoid scratches on the surface and ensure the lubrication of the part.
In the process of precision CNC machining and milling closing, if the curve of internal generalization is allowed to be extended, it should be cut in and out along the tangent direction. If the inner generalization curve does not allow extension, the cutter can only cut in and out along the normal direction of the inner generalization curve, and the cutting in and out points are selected at the intersection of two elements of the mechanical part generalization. When there is no intersection point of several internal elements, the cutting point should be far away from the corner in order to avoid the notch left at the general corner when the cutter compensation is withdrawn.

The above are the skills in the process of precision CNC milling, simple and complex precision parts processing, CNC milling technology will be different, according to the appropriate processing line.

ken. tang@chengcg.com

The difference between 3-axis and 4-axis CNC machining is as follows

In the field of machining industry, CNC machining is often mentioned, which is divided into three-axis CNC machining and four axis CNC machining. There are also five axis CNC machining. At present, it is widely used in the three-axis and four axis markets.

Three axis CNC machining: generally refers to three different directions of linear motion axis, such as up and down, front and back, left and right. Three axis can only process one face at a time, which is suitable for processing some plane parts. The technology of parts is simple and small batch parts processing.

Four axis CNC machining: add a rotation axis on the three axis, generally 360 ° Spin. But it can’t rotate at high speed. It can make the product multi-faceted processing by rotating, greatly improving the processing efficiency and reducing the clamping times. In particular, the processing of cylindrical parts is more convenient. And it can reduce the repeated clamping of the workpiece, improve the overall processing accuracy of the workpiece, simplify the process and improve the production efficiency. It is suitable for machining some box and complex precision parts.

The above is the difference between three-axis and four axis CNC processing. You may ask why five axis CNC processing is not mentioned. Although five axis CNC processing has outstanding advantages over four axis and three-axis CNC processing, not all products are suitable for five axis CNC processing, and those suitable for three-axis CNC processing are not necessarily suitable for five axis CNC processing. If the original three-axis products can be processed by five axis CNC processing, Not only will it increase the cost, but the effect is not necessarily good. Only reasonable arrangement, for the product to develop the appropriate machine tools, so as to play out the value of the machine itself.

ken. tang@chengcg.com

CNC parts processing technology skills

Now understand the CNC parts processing technology and operation skills. Mechanical parts processing is under the established production conditions. For the reasonable process and operation method, the processing method is compiled in the prescribed form to guide the production and processing steps after approval. With the continuous change of CNC machining system, take a look at the precision machining manufacturers of CNC parts processing, and summarize the following points.

It can be understood as a small skill in the process of precision CNC machining

In the process of precision parts processing, when the hexagon wrench is short and can not bear the pressure, the pipe with the inner diameter slightly larger than the wrench can be inserted into the groove from a part of the milling groove. Inside the slot, it can be used as a long handle. In the process of CNC machining, many precision parts are not produced at one time, but when mechanical parts are produced, it is just a rough model. If the processing factory becomes a real product, it is also processed by some mechanical equipment according to different production and processing processes. Processing can eventually become a valuable product.
Precision CNC machining, using magnet to absorb small parts (cost) is not convenient to suck. The iron plate can be sucked under the magnet, which can not only suck many small pieces, but also pull out the iron plate from the small pieces, which will automatically pour into the collection box immediately. Not impressive enough, but very practical.
When driving the pulley in precision CNC machining, the pulley often slides between the pulley and the shaft. Draw a series of sockets on the shaft with 15 ~ 18mm trocar. This can form adsorption to prevent slipping, and turn waste into treasure, improving the value of long-term use.
In CNC machine tool processing, it is necessary to remove the jaws of vise, add two M4 threaded holes, two steel plates with jaws and 1.5mm thickness, rivet the hard brass plate with aluminum countersunk head rivet and 0.8mm thickness, and fix the hard brass plate on the jaws with M4 countersunk head screw to form a durable soft jaw. This can also protect precision parts from being damaged by clamping, and can be reused. It can be regarded as protecting the appearance details of precision CNC machining.

The above is about CNC parts processing technology tips, many precision parts processing requirements are relatively high, the use of tips can avoid quality problems and improve production and processing efficiency!

ken.tang @ chengcg.com

Development of CNC processing industry in 2021

2021 is destined to be an extraordinary year. At present, the domestic epidemic situation has been stable, while the foreign epidemic situation is still rising. For the machinery manufacturing CNC processing industry, the business impact on the foreign trade market is very large. Where is the development direction in the second half of 2021? Let’s take a look at the following points:

The foreign market has a huge impact: many of them have not returned to work, and the demand for CNC processing is almost zero. But we can not give up the market, take the initiative to contact customers, and at the same time open up new markets.
Large domestic demand, seize the opportunity: it can be said that the domestic epidemic has been completely controlled, the demand of all walks of life is rising, especially the precision CNC processing customers, such as electronic optics, mobile communication, medical equipment and other industries, need CNC processing outsourcing cooperation. As long as we do a good job in quality and service to customers, orders will grow slowly.
Independent innovation, R & D of products: for the mechanical processing industry, R & D of products is a very difficult thing. We need technology without technology, market without market, and talents without talents, unless we have abundant funds, talents or market demand.

ken.tang @ chengcg.com

Structure of CNC machine tool

At present, in the Pearl River Delta Dongguan region, CNC machining machine on the bed is very common. It is a machine tool with automatic program control system. To understand the CNC machining system structure principle, in the CNC machining process, can logically deal with the control code or other symbols and instructions of the program, and its decoding, so that the machine action and processing mechanical parts, collectively referred to as CNC machining.

The structure of CNC machine tool is as follows

Main machine, which is the theme of CNC machine tools, including machine body, column, spindle, feed mechanism and other mechanical parts. He is used to complete a variety of cutting precision parts processing.
Numerical control device is the core of CNC machine tool, including hardware and corresponding software, which is used to input digital part program, complete input information storage, data transformation, interpolation operation and realize various control functions.
Driving device, which is the driving part of CNC machine tool actuator, including spindle driving unit, feed unit, spindle motor and feed motor. Under the control of the numerical control device, he realizes the spindle and feed drive through the electric or electro-hydraulic servo system. When several feed linkage, can complete the positioning, straight line, plane curve and space curve processing.
Auxiliary device refers to some necessary supporting parts of CNC machine tool to ensure the operation of CNC machine tool, such as cooling, chip removal, lubrication, lighting, monitoring, etc. It includes hydraulic and pneumatic device, chip removal device, exchange table, numerical control turntable, numerical control dividing head, cutting tool, monitoring and detection device, etc.
Programming and other auxiliary equipment, which can be used to program and store CNC parts outside the machine.

The above is the structure of CNC processing. In the machining industry, precision CNC processing greatly improves production efficiency. Its main advantages are as follows:

① It can ensure the accuracy and surface roughness of the workpiece to be processed;

② It can shorten the processing route, reduce the empty travel time and improve the processing efficiency;

③ The workload of numerical calculation should be simplified as much as possible, and the machining program should be simplified;

④ For some repeated programs, subroutines should be used.

ken.tang @ chengcg.com

CNC lathe preparation process

In the field of machining, CNC machine tool is very common and has a wide range of applications. At present, it is a kind of processing equipment often used in the field of precision machining. When using the machining center, the maintenance of the corresponding processing equipment can not be ignored, whether before use or after use. Now let’s understand the preparation process of CNC machining center

During precision CNC machining, the workpiece should be put down gently to prevent damage to the worktable; When the CNC machining workpiece is heavy, the bearing capacity of the machine tool table should also be verified, and the CNC machining machine tool is not allowed to overload.
CNC machining program should be checked before it can run. When using CNC machining high-speed function, it is necessary to confirm the matching of cutting tools and the reasonable selection of parameters.
After the operator starts the CNC machine tool, check whether the movement of the spindle and worktable in all directions is normal, whether there is abnormal noise, etc., and stop the operation immediately after finding the problem.
In the process of precision parts processing, we should always pay attention to whether the movement and processing state of the machine tool are normal or not. In case of noise and alarm, the machine should be shut down immediately for inspection and treatment, and the CNC machine can continue to process after troubleshooting.

ken.tang @ chengcg.com

Precision parameter control of CNC machining

In the machining industry, CNC processing is also known as computer gong processing. It refers to the processing steps that are completed by the NC command of the programmer. Now let’s take a look at the accuracy parameters of CNC machining. It is mainly the level that the specific geometric parameters (specification, shape and position) of CNC parts are consistent with the ideal geometric parameters. Detailed understanding of the following parameters:

In the process of machining mechanical parts and small batch parts, CNC machining accuracy usually includes three levels of parameters: specification accuracy, shape accuracy and position accuracy.

Shape and specification parameters of CNC machining

The specific specification of the surface itself or the middle of the surface after machining of CNC parts is consistent with that of the ideal part. The ideal part processing specification refers to the median value of the specification indicated on the part drawing.

Shape precision parameters of CNC machining

The specific shape of the machined surface of CNC parts is consistent with that of the ideal parts. The ideal surface shape of a part refers to the positive surface geometry shape.

Position precision parameters of CNC parts processing

After CNC parts are processed, the specific parts of each surface are consistent with the parts of each surface of the ideal parts. The position between the surfaces of ideal parts refers to the positive position between the surfaces.

The above is the precision parameter control of CNC machining. For different shapes, shapes, simplicity and complexity, it is necessary to select appropriate processing parameters to improve CNC machining efficiency and ensure the machining accuracy of parts.

ken.tang @ chengcg.com

Surface treatment technology of CNC machining

In the field of precision CNC machining, the working performance and service life of parts with high requirements for strength and toughness are closely related to their surface properties. However, the improvement of surface treatment performance can not be achieved simply by relying on materials, which is also very uneconomic. However, in the actual processing, its performance must meet the standard. At this time, surface treatment technology is needed . Let’s take a look at the surface treatment process of CNC machining

Hardware mold industry, CNC processing of mold accessories, process polishing technology is a very important link, but also an important process in the process of workpiece processing. The surface treatment process of precision mechanical parts is very important in the process of processing. It is worth reminding that the polishing of the mold surface of precision parts is not only affected by the process and polishing equipment, but also affected by the specularity of the parts. This point has not been paid enough attention in the current processing, which also shows that the polishing place is very important The process itself is affected by the material.
Precision CNC machining. At present, the machining technology to improve the surface properties of precision parts is constantly upgraded. However, the main applications in the machining of precision CNC parts are hardening film deposition, nitriding and carburizing technology. Because the nitriding technology can obtain a high level of surface properties, and the nitriding technology process has a very high consistency with the quenching process of steel in precision parts.
Surface treatment details. The temperature of nitriding is very low, so there is no need for intense cooling process after nitriding technology treatment, so the deformation of precision machined parts will be very small. Therefore, nitriding technology is also one of the early technologies used to strengthen the surface properties of precision mechanical parts, which is widely used at present.

ken.tang @ chengcg.com

Steps of precision CNC machining

Before precise CNC machining line, each processing method has its processing sequence. Our operators need to process according to their processing order, but they can’t process at will, which will have a certain impact on the processed products or quality problems. Precision machining is one of them. What is the sequence of CNC machining? For precision parts, machining must be based on the structure of the parts and the condition of the blank, as well as the requirements of positioning and clamping. The key point is that the rigidity of the workpiece is not damaged. There are the following points

1、 The familiar understanding of precision parts processing technology can be divided into several points

How to deal with the previous process will not affect the positioning and clamping of the next process. The middle cross section has a general fine parts processing process.
First stop the adding process of the inner cavity, and then stop the shape processing process.
It is better to use the same positioning, clamping method or the same tool to stop the process, so as to reduce the times of repeated positioning, tool change and the number of moving platens. Dongguan Machinery processing factory method.
In the multiple processes stopped in the same device, the process of destroying the workpiece stiffness should be arranged first.

2、 Tool concentration sequence method: the whole process is divided according to the tools used by precision machining manufacturers, and all parts on the parts can be completed by using the same tools. Other parts can be completed successfully by using other tools. This can reduce the number of tool change, shorten the dead time and reduce unnecessary positioning error.

3、 Sorting method of processing parts: for parts with a large number of processing contents, according to their structural characteristics, processing parts can be partially red, such as internal shape, shape, surface or plane. Common processing plane, positioning surface, after processing hole; first processing simple geometry, and then processing complex geometry; first processing low precision parts, and processing high precision parts.

ken.tang @ chengcg.com

Causes of CNC machining accuracy

In the field of machining industry, what are the reasons for the influence of CNC machining accuracy?

The first is the error of position influence: it usually refers to the mutual position change or deviation degree of the actual surface, axis or symmetry plane of the machined part relative to its ideal position, such as perpendicularity, position degree, symmetry degree, etc.
Machine error: the error of the machine itself usually refers to the dead angle error. The main causes of position error are the machining error caused by the gap and elastic deformation of the transmission in the machining process of machine tool parts, and the position error caused by the friction that the tool head needs to overcome in the machining process. In the open-loop system, the position accuracy is greatly affected, while in the closed-loop servo system, the position accuracy mainly depends on the displacement detection.
Geometric error: machining accuracy error caused by geometric error of CNC machining. In the process of CNC machining, the geometric accuracy of the machine tool is affected by external factors such as external force and heat generated in the process. The geometric deformation of the parts processed on the machine tool will lead to geometric error. According to research, there are two main reasons for geometric error of CNC machine tools: internal factors and external factors. The internal factors that cause the geometric errors of machine tools refer to the geometric errors caused by the factors of machine tools, such as the levelness of machine tool table, the levelness and straightness of machine tool guide rail, the geometric accuracy of machine tools and fixtures, etc. The external factors mainly refer to the geometric errors caused by the influence of external environment and thermal deformation. For example, the geometric errors caused by the thermal expansion and deformation of cutting tools or parts in the cutting process will affect the machining accuracy of machine tools and parts.
Cumulative error: from the long-term data analysis and actual operation of parts processing, we can see the machining accuracy error caused by CNC machine positioning. The positioning of machine tool has a great influence on the machining accuracy of NC machine tool. From the structure point of view, the machining error of CNC machine tool is mainly caused by the positioning accuracy, and the feed system of machine tool is the main link affecting the positioning accuracy. The feed system of CNC machine tool is usually composed of mechanical transmission system and electrical control system. In structural design, positioning accuracy is related to mechanical transmission system. In the closed-loop system, CNC machine tools usually can prevent the position deviation of the main parts (such as ball screw and other parts) in the feed system by positioning detection device. However, for the open-loop system, due to many factors and complex conditions, it is impossible to carry out positioning monitoring, so the machining accuracy of CNC machine tools is greatly affected.

The above explanation is the reason for the influence of CNC machining accuracy in Dongguan. I hope it will be helpful to you after reading.

ken.tang @ chengcg.com

Monthly Archive April 27, 2021

Milling technology in precision CNC machining

The difference between 3-axis and 4-axis CNC machining is as follows

CNC parts processing technology skills

Development of CNC processing industry in 2021

Structure of CNC machine tool

CNC lathe preparation process

Precision parameter control of CNC machining

Surface treatment technology of CNC machining

Steps of precision CNC machining

Causes of CNC machining accuracy

CNC Machining parts

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