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

Advantages of CNC thread milling cutter and tap tapping

Nowadays, manufacturers have more and more strict requirements on cutting tools. Maybe a small tool determines the quality of this product. The thread milling cutter has many advantages, which is much better than the wire tapping. The thread milling cutter is more than ten times faster than the wire tapping, and has high precision and good surface roughness. The same pitch can get large and small holes, which can be processed with one cutter. The drilling and milling thread chamfering can be formed at one time, and it will not be taken out like the wire tapping after it is broken, and the resistance of the machine tool is also small.

Thread milling cutter introduction:

The traditional thread processing methods are mainly turning thread with thread turning tool or manual tapping with tap and die. With the development of NC machining technology, especially the appearance of three-axis NC machining system, a more advanced thread machining method, NC milling of thread, has been realized. Compared with traditional thread processing, thread milling has great advantages in processing accuracy and efficiency, and is not limited by thread structure and thread direction. For example, a thread milling cutter can process a variety of internal and external threads in different directions. It is very difficult to machine the thread with transition thread or undercut structure by traditional turning method or tap and die, but it is very easy to realize by NC milling. In addition, the durability of thread milling cutter is more than ten times or even tens of times that of tap, and in the process of NC milling thread, it is very convenient to adjust the diameter of thread, which is difficult to do with tap and die.

Classification of thread milling

Clip on type:

Single tooth machine clamp: mechanical structure is similar to thread turning tool. The blade is connected with the turning tool and has only one thread processing tooth. The cutter can only process one tooth per spiral movement cycle, and the corresponding pitch decreases by one in the z-axis direction. The efficiency is lower than that of the multi tooth machine clip thread milling cutter

Multi tooth machine clamp: there are many thread processing teeth on the blade. When the cutter rotates for one circle, it can process many thread teeth by reducing the pitch of the corresponding number of teeth on the z-axis, with high processing effect

Integral type:

Integral type: there are many thread processing teeth on the blade, which is a kind of fixed pitch thread milling cutter. The cutter is made of integral cemented carbide, with good rigidity, high cutting speed and feed speed, wide processing range, compact structure, and can process small and medium diameter internal threads. But its price is more expensive

Characteristics of thread milling

1 stability

When machining difficult to machine materials such as titanium alloy, superalloy and high hardness materials, the tap will often twist or even break in the parts due to too much cutting force. In the process of long chip material, once the chip removal is not smooth, the chip will wind the tap or block the hole, which often leads to the tap crack or broken in the parts. Taking out the broken tap is not only time-consuming and laborious, but also may damage the parts. To solve this problem, we can use thread milling cutter. Because the thread milling cutter cuts into the material gradually, it produces less cutting force and seldom breaks. Even in case of tool breakage, because the diameter of the milling cutter is much smaller than that of the threaded hole, the broken part can be easily removed from the part without damaging the part

High precision

Because the thread milling is through the tool high-speed rotation, spindle interpolation way to finish processing internal thread, chip removal is convenient. Milling thread belongs to chip breaking cutting, and the chip is short. In addition, the diameter of machining tool is smaller than that of machining thread, which can avoid the turning line formed by tap reversal (it is not allowed in the case of high sealing requirements). Because there is no turning line in the original milling cutter, and the tap can not be avoided. It is not easy to form sticky chips. For soft materials, chip sticking is easy to occur in the process of processing, but the screw thread requires low machine power. Because thread milling is chip breaking cutting, tool contact is local, cutting force is small, and tap tool damage is easy to deal with;

High efficiency

Processing efficiency we know that in the mass thread processing, due to the low cutting speed limit of the tap and the reverse tool withdrawal after processing the thread, it is very difficult to improve the processing efficiency. However, if we use thread milling cutter, not only its own milling speed is very high, but also its multi groove design increases the number of cutting edges, which can easily improve the feed speed, which can greatly improve the processing efficiency. In the processing of long thread, we can also choose the blade with longer blade to reduce the axial feed distance (equivalent to making the thread shorter) to further improve the processing efficiency;

Good finish

Due to the influence of low cutting speed and difficult chip breaking, it is very difficult to obtain good surface finish and thread precision when machining with tap. However, for thread milling, everything is not a problem! High cutting speed and small cutting force make the cutting surface smooth; The fine chips can be easily washed out by the coolant, and the workpiece will not scratch the machined surface. For the workpiece with high thread accuracy requirements, because the thread milling cutter relies on spiral interpolation to ensure the accuracy, only need to adjust the program to easily obtain the required high-precision thread. This feature has a great advantage in precision thread processing.

Low cost

The thread milling cutter is flexible and can be used in various working conditions. For example, we can use the same thread milling cutter to process left-hand thread or right-hand thread; It can process both external thread and internal thread. All this just needs to be done by adjusting the interpolation program. If there are multiple threaded holes with different diameters but same pitch on the part, taps with different diameters are needed. This not only requires a lot of taps, but also takes a lot of time to change the tool. If the thread milling cutter is used, because it uses spiral interpolation to process, it only needs to change the processing program to complete the processing of all diameter threads, which greatly saves the cost of the cutter and the time of tool change. In order to ensure the thread accuracy, different types of taps are needed when machining different materials with taps. However, the use of thread milling cutter has no such limitation. The same thread milling cutter can process most materials and obtain high precision thread. This can also greatly reduce the cost of cutting tools. When the processing thread is close to the bottom of the blind hole, it is difficult to obtain the complete thread at the bottom if tapping with tap. And it is possible that the tool will continue to move forward a little distance (floating tapping) during the time when the tap stops at the bottom and is ready to reverse back, which is easy to cause the tap to break. This problem can be avoided by using the thread milling cutter – the thread milling cutter is smaller than the hole, there is no need to reverse the tool, and the thread shape is still complete at the tool tip. In this way, we can get complete and precise thread depth! In some processing, thread milling can help us solve many problems.

ken. tang@chengcg.com

Function of CNC milling machine and grinder

At present, numerical control equipment is more and more common, there are many kinds of ordinary machine tools.

Lathe

It is mainly used for machining various rotating surfaces and end faces of rotating body. For example, turning inner and outer cylindrical surface, conical surface, ring groove and forming rotating surface, turning end face and various common threads, processing equipment can also process various special shapes. Drilling, reaming, reaming and knurling can also be carried out on the lathe.

Milling machine

The utility model relates to a multifunctional machine tool, which can process plane (horizontal and vertical), groove (keyway, T-groove, dovetail groove, etc.) and surface (thread, spiral groove) of split parts (gear, spline shaft, sprocket, screw) and various curved surfaces. In addition, it can also be used for machining and cutting the surface of the rotating body. When the milling machine is working, the workpiece is installed on the worktable or dividing head and other accessories. The tool rotates as the main motion, supplemented by the feed motion of the worktable or milling head, the workpiece can obtain the required machining surface. The productivity of milling machine is very high because of multi cutter intermittent cutting.

Planer

It is mainly used for processing all kinds of plane (such as horizontal, vertical and inclined surfaces, and all kinds of grooves, such as T-shaped groove, dovetail groove, V-shaped groove, etc.) and linear forming surface. If equipped with contour processing device, it can also process space surface, such as turbine wheel, spiral groove, etc. This type of machine tool has a simple tool structure, and will not cut when returning, so the productivity is low, and is usually used for single piece small batch production.

Trampoline

It is suitable for plane milling and hole machining of single batch or small batch parts in machining workshop. The end of the headstock is designed with a flat rotating disc tool holder, which is used to drill large holes and planes. In addition, it can also drill, ream and thread.

Grinding machine

A kind of machine tool, which uses grinding abrasive (grinding wheel, abrasive belt, oilstone, abrasive, etc.) as a tool to cut the surface of workpiece, is collectively referred to as grinder. Grinding machine can process all kinds of surface, such as inner and outer cylinder and cone surface, plane, gear tooth surface, spiral surface and all kinds of forming surface, as well as grinding tools and cutting, etc. Because grinding is easy to obtain high machining accuracy and good surface quality, grinding machine is mainly used for finishing parts, especially hardened steel parts and high hardness special materials.

Drilling machine

Multifunctional machine tool, suitable for drilling, reaming, reaming, boring and tapping and other applications. When the radial drilling machine is equipped with process equipment, it can also be used for drilling; The drilling rig can be equipped with a universal worktable (mdt-180 type) or milling keyway.

Gear machine

Gears are the most commonly used transmissions, including cylindrical gears with straight, spiral and herringbone teeth, bevel gears with straight and spiral teeth, worm gears and non-circular gears. The processing gear tooth surface machine tool is called gear processing machine tool.

ken. tang@chengcg.com

Fast WEDM method for CNC parts

For the current processing industry, wire cutting is a very common cutting process, for fast cutting wire cutting, the same mechanical equipment, in the hands of different people after the operation of the product quality will have a certain difference, will also have a certain impact on the normal use of the machine tool. Here, first of all, find the cutting line.

The line method is correct. If you are working on a multi-layer thin-walled sheet metal part because it is affected by dimensions such as welding or blanking, the edges of the plate will not be neat. At this time, if the cutting accuracy is not high. In this case, it can be done by using chemical fiber arrangement method or by manual method.
Alignment method of paper pattern. This alignment method is also a common method. When the multi-layer thin-walled bow and arrow is used for cutting shape processing, it is necessary to operate the inner contour or hole. Then, it is necessary to perform the silk pre threading operation in multiple places. At this time, we can paste one-to-one pattern on the workpiece to be processed, which will not only lead to the deviation of wire hole, but also lead to wire cutting. It will also become easier. Rapid cutting wire cutting is also a technology of cutting internal control, keyway or outer circle, which makes tooth shaped workpiece possible.
For the process hole to be corrected, many workpieces should be processed according to the processing steps. Generally, this process should be carried out at the bottom of the plate

Left and right and diagonal. In this case, the size of the machining hole or the quality of the surface is a better situation. You can use the corresponding hole on the bridge tool, and then use the position of the tip to perform the alignment.

Universal table alignment is also a common alignment method using fast WEDM technology. The most important feature of this correction method is that the accuracy is relatively high, so the probability of using it is relatively large.

Fast cutting line is one of the cutting methods currently used. This cutting method needs higher cutting technology, but cutting technology is actually based on cutting experience, so for the operator, we must accumulate some experience.

ken. tang@chengcg.com

Basic knowledge of CNC machining

Cutting is the use of cutting tools from the blank (or profile) to cut off part of the excess material, the blank will be processed to meet the drawing requirements of the size, shape accuracy and surface quality of parts processing process. Cutting is divided into machining and fitter two parts. Machining is a kind of cutting process which is completed by workers operating machine tools. The main processing methods include turning, milling, planing, drilling, grinding and gear processing. Fitter is generally carried out by workers hand tools cutting. The processing of products is usually divided into four stages: rough machining, semi finishing, finishing and finishing. This section only introduces turning, milling, drilling, grinding in machining and marking, sawing, filing, chiseling, tapping and threading, assembly in fitter.

ken. tang@chengcg.com

The speed of CNC machine tool

With the improvement of the performance of the core processor of the CNC system, the feed speed limit of the high-speed machining center can reach 80 m / min, and the idle speed can reach about 100 m / min. At present, many automobile factories in the world, including Shanghai General Motors Company in China, have partially replaced modular machine tools with production lines composed of high-speed machining centers. The feeding speed limit of hypermach machine tool of Cincinnati company is 60m / min, the speed is 100M / min, the acceleration is 2G, and the spindle speed has reached 60000r / min. It takes only 30 minutes to process a thin-walled aircraft part, while it takes 3 hours for the same part to be processed on a general high-speed milling machine and 8 hours on a general milling machine. Due to the specialization of each component of the mechanism, under the development of professional spindle factory, spindle high-speed is increasingly popular. In the past only used for high-speed automobile industry models (15000 rpm or more), now has become a necessary mechanical product requirements.

ken. tang@chengcg.com

CNC hard rail machining and wire rail machining

In the machining industry, iron parts belong to the more common processing work pieces. When machining iron parts with machining center, do you choose the hard rail machining center or the line rail machining center? Today, I’d like to answer your questions

When choosing the hard rail machining center and the line rail machining center, the machining manufacturers need to know the size of the iron pieces they are machining, whether they are finishing or rough machining and other details. Only by understanding these details, can the manufacturers who are specialized in CNC machining center give an accurate answer.

Generally, the quality of large-size iron parts is large, and the amount of cutting is relatively large. In this case, it is more appropriate to choose the hard rail machining center. The hard rail machining center has strong rigidity, earthquake resistance and load-bearing capacity, and is more suitable for heavy-duty cutting. In this case, if the line rail machining center is used for a long time, the guide rail may be damaged. Generally, customers are advised to use hard rail CNC machining centers. For example, T-8, T-10, T-12, T-13 and T-15 belong to hard rail machining centers. Compared with 850, 1060 and 1270 in the market, these hard rail CNC machining centers are generally suitable for heavy load cutting.

ken. tang@chengcg.com

Precautions for CNC machining

At present, numerical control machining can not get rid of the fate of the industry in the modern era, and there will be some errors in the process of machining

Wrong processing principle

The main error of CNC machining is caused by approximate machining motion or approximate tool profile. Because of the error of machining principle, it is called machining principle error. As long as the main error is within the allowable range, this type of processing is still feasible.

Geometric error of machine tool

Machining error, installation error and wear during use directly affect the machining accuracy of the workpiece. It includes the rotation of the spindle, the linear motion of the guide rail and the error of the transmission chain.

Manufacturing error and wear of tools

The manufacturing error, installation error and wear of CNC machining tools in the process of machining will affect the machining accuracy of the workpiece. In the cutting process, the cutting edge, cutting surface, workpiece and chip produce strong friction, which leads to tool wear. When the tool wear reaches a certain value, the surface roughness of the workpiece increases, and the color and shape of the chip change. With the vibration, the tool wear will directly affect the cutting productivity, processing quality and cost.

Fixture error

CNC machining fixture error includes positioning error, clamping error, fixture installation error and tool setting error. These errors are mainly related to the manufacturing and assembly accuracy of the fixture. CNC machining accuracy is not perfect, as long as the error is controlled in a certain range, it will not have any significance. Tool manufacturing error and wear.

Positioning error

Positioning error mainly includes reference misalignment error and locator manufacturing error. When machining the workpiece on the machine tool, several geometric elements on the workpiece must be selected as the positioning reference. If the selected positioning reference and design basis are used (reference is used to determine the table on the part drawing)

Face size and location). If misalignment occurs, a reference misalignment error will occur. The positioning surface of the workpiece and the positioning part of the fixture form a positioning pair. Large displacement of workpiece caused by inaccurate positioning position and matching gap between positioning pairs is called positioning. Sub manufacturing inaccuracy

Wrong. The inaccuracy in positioning and manufacturing only occurs when the adjustment method is used, and will not occur in the trial cutting process.

Adjustment error

In each process, the process system is always adjusted in some way. Because the adjustment is impossible to be accurate, there is an adjustment error. In process

In the system, by adjusting the machine tool, cutter, fixture or workpiece, the mutual position accuracy of workpiece and cutter on the machine tool is ensured. When the original accuracy of machine tool, tool, fixture and workpiece blank meets the process requirements without considering the dynamic factors, the adjustment error plays a decisive role in the machining error.

Measurement error

When measuring parts during or after machining, the measurement accuracy is directly affected by the measurement method, measuring tool accuracy, workpiece and subjective and objective factors. To a certain extent, the above seven machining errors can be avoided, so the operators who need to process can test the six machining processes that may cause machining errors more carefully. After machining operation, the influence of machining error can be reduced better.

The above is for you to share the “CNC processing to pay special attention to a few places.”.

ken. tang@chengcg.com

Overall level of CNC machining capability

First of all, let’s understand the so-called mechanical processing. As long as it is related to mechanical processing, it can be said that it is a mechanical processing industry. It can be divided into a broad sense of mechanical industry and a narrow sense of mechanical processing industry. At present, China’s mechanical processing industry is relatively backward. Compared with the west, most of them are self-employed small workshops, and they are generally processing with supplied materials, All the drawings of the equipment are from foreign countries. However, in the coastal areas, although they are small individual workshops, most of them already have CNC equipment, and the processing efficiency is relatively high. Generally, CNC processing is the main method, as well as mechanical parts processing.

In the Pearl River Delta region, it is very common for machining manufacturers to have CNC processing equipment, which is suitable for processing complex precision parts, especially for small batch and large batch parts processing. Improve the quality of parts processing, but also improve the efficiency of production and processing! At present, the machining capacity is improving rapidly, and most of the machining manufacturers can meet the needs of small batch processing. However, compared with the west, the machining industry still has a long way to go. It can be divided into three parts

Unbalanced development and low overall product standard. Although the products of individual enterprises have reached or approached the international standard, there is still a big gap between the precision of precision parts processing, roughness of special surface, production cycle, life and other indicators and foreign standards.
Backward technology and equipment, poor organization and coordination ability. Although some enterprises have undergone technological transformation in recent years, their technology and equipment level has been compared, and the equipment level of some foreign-funded enterprises is not behind that of foreign countries.

The above is the overall level of machining capacity. It is believed that through the continuous development of domestic small and medium-sized enterprises, they will soon draw closer to the West and even catch up with the West.

ken. tang@chengcg.com

Factors of improving efficiency in CNC machining

To see what is the efficiency factor of CNC machining, we must first know that CNC machining center belongs to numerical control equipment, which is mainly operated by the computer programming command of technical engineers. In the process of production, how to improve the efficiency of CNC processing

Selection of machine tools

Before arranging CNC parts processing, we must ensure the weight that the worktable can bear and consider the smooth processing of mechanical parts. Nowadays, the efficiency of production and processing has a direct impact on whether small and medium-sized processing enterprises can make profits. If the machine tool table can not meet the requirements of use, the processing efficiency will be reduced, and the accuracy of the machine tool itself will also be affected.

Reasonable processing steps

For the machining industry, it can be said that reasonable production and processing technology is one of the important steps. CNC parts processing is very difficult, so we must choose a reasonable processing route, which can save time and improve the production and processing efficiency. On the contrary, if the selection of processing technology is unreasonable, the production efficiency will be reduced.

Small batch processing

Whether it can be processed in small batch, when it comes to processing in small batch and large batch, the advantage of precision CNC processing is very obvious, which saves the time of programming, adjusting machine and so on. Only need to clamp parts repeatedly, the production and processing efficiency can be improved many times! Therefore, most machining manufacturers prefer small batch processing

The above is the mechanical plus CNC processing rate factor

ken. tang@chengcg.com

On the tolerance of precision parts processing

For the precision machining industry, the tolerance of production drawing parts processing. A precision parts processing drawings will have dimensions, special position machining accuracy requirements, that is, positive and negative tolerance. The marked tolerance is to ensure that the actual geometric parameters are consistent with the dimensions specified on the drawing in the process of precision parts processing, and the degree of inconsistency between them is called processing error. In order to ensure the accuracy tolerance and avoid the machining error, the following three points should be paid attention to

Benchmark:

According to the shape of different parts, the same datum plane can be selected for processing to ensure that the clamping of parts in the processing process can reduce a certain error range, which is the importance of datum plane.

Shape:

For different drawings provided by our customers, the workpiece with special shape can’t be clamped normally. At this time, we can consider designing clamping fixture for positioning processing and selecting datum plane. Its main function is to assist the processing to meet the accuracy requirements and improve the production and processing efficiency.

Technology

In the precision machining industry, some people say that the drawing processing technology is an art, reasonable technology will save a lot of time, but also can improve the efficiency of production and processing. So a reasonable process is very important.

Machine tool:

Previous articles have also mentioned that the accuracy of the machine tool itself will affect the error, because there are several kinds of errors of the machine tool itself, mainly including the head spindle rotation error, guide rail error and transmission chain error.

The above is about the tolerance of precision parts processing, for parts processing requirements are higher and higher, how to ensure the accuracy of the size.

ken. tang@chengcg.com

Monthly Archive April 30, 2021

Advantages of CNC thread milling cutter and tap tapping

Function of CNC milling machine and grinder

Fast WEDM method for CNC parts

Basic knowledge of CNC machining

The speed of CNC machine tool

CNC hard rail machining and wire rail machining

Precautions for CNC machining

Overall level of CNC machining capability

Factors of improving efficiency in CNC machining

On the tolerance of precision parts processing

CNC Machining parts

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