March 2020 – Page 3 – CNC Machining & Turning, Milling, Metal parts

Precision parts processing can meet your requirements

We will use many parts in our life, that is to say, we will use many parts when we use many machines. But our parts can’t be precise occasionally. At this time, we might as well go to buy precision parts. Why? Because a original precision part might as well be worth a lot of our ordinary parts. Without this good precision part, many of our machines would be very difficult to use.

But we often have such things, that is, we will occasionally find our own precision parts are still not good. Take the car for example, if our car breaks down, we go to buy parts, buy precision parts and find that it still cannot meet the requirements of our car. Then you need such equipment for precision parts processing, that is to say It is such a simple thing to process the precision parts you still buy and then meet the requirements of your machinery.

Precision parts processing, to meet any requirements of your machinery.

The influence of ultra precision CNC machining technology

Ultra precision CNC machining technology has significant economic benefits, social benefits and market demand prospects: ultra precision machine tool is the carrier of high-level CNC machining technology, with high development cost, long cycle and high value of each machine. If it can replace the import of an ultra precision machine tool, it will save millions of dollars; if the value of its annual machining creation is calculated, the economic benefits are significant.

Ultra precision CNC machine tool is an indispensable equipment for the development of national defense cutting-edge and high-tech products. It has always been regarded as a strategic material by some powerful family property countries and is banned for export. If China does not develop its own machine tool, it is difficult to buy it if necessary, so the social benefits are great.

With the development of science and technology and people’s economy, the demand for ultra precision machining technology is becoming more and more superior, and the market is expanding. Its application is not limited to the cutting-edge of national defense and aerospace, but has expanded to various boundaries. Its application scale and demand are larger, so the market demand prospect is optimistic. The detailed analysis is as follows.

The use of CNC processing is becoming mediocre and the market demand is expanding. The boundary of ultra precision CNC processing technology is becoming more and more mediocre, which is used in the boundary of high-tech technology, military property and civil property. Therefore, it is an indispensable skill for the development of high and new technology and products.

Machining quality of precision parts is expressed by machining precision

1、 Interchangeability of parts

According to the precision parts manufacturer, after long-term production and operation, some parts will inevitably wear and deform and be scrapped, replacing with new parts. These parts are called accessories or spare parts. Accessories or spare parts without repair or selection, installed on the machine can run, known as exchange.

In order to achieve interchangeability, when manufacturing parts, we should make the size and geometry of the parts as a whole. The so-called “all in all” does not require that the score is not poor at all (it is neither economical nor possible to do so). As long as the size and geometry of the parts are controlled within a promised boundary, so that the parts and other parts have the same fusion function after fusion. The promised deviation line is the official of form and position.

2、 The machining quality of precision parts is expressed by machining accuracy:

1. Geometric form accuracy

The accuracy of geometric form refers to the accurate level of geometric form such as the surface or axis of the part, such as whether the line is straight, whether the surface is flat, and whether the normal section on the cylinder is round, etc. The allowable change boundary is expressed by “shape and position yamen servant”. The smaller the number of shape and position yamen servant is, the higher the form accuracy is.

2. Dimensional accuracy

According to the analysis of precision parts processing factory, dimensional accuracy refers to the accurate level of the dimension after the parts are processed, which is represented by “dimension yamen runner”. When the dimensions of the parts are the same, the higher the accuracy, the smaller the Yamen number.

3. Position accuracy

According to the precision parts manufacturer, the position accuracy refers to the accurate level of the mutual position between the surfaces of the parts, such as whether the two planes are parallel, vertical, and whether the two axes are coaxial.

The Yamen servants in the above forms and positions are referred to as “yamen servants in shape and position”.

CNC machining tools improve machining process

The development of new CNC milling cutter provides CNC machining tools with higher cutting strength and easier use for CNC machining center and milling machine. With the development of design and manufacturing technology, the sophisticated cutter body and blade can be used to improve the fraud rate of machine tools, increase output and increase the reliability of machining process.

Normalization is very important for manufacturing industry, because only through normalization can CNC processing technicians communicate in the same language and understand the limits of use. However, in some cases, the criteria may slow down or even hinder the development of products. At this time, it is necessary to get rid of constraints, break barriers and introduce better plans. One example is the development of CNC milling cutter.

For many years, users have followed the rules and regulations and exchanged CNC milling cutters and blades made by various CNC machining tool manufacturers. However, these guidelines have made various restrictions on CNC machining milling cutter and blade, including blade form, thickness, internal circle of cutting blade, size of blade holder and wedge clamping piece, and size of cutter body. Due to the limited design boundary of blade material, cutting edge and chip breaking groove, the suppliers and products of CNC machining tools that abide by the rules are limited by machining functions.

Today, however, CNC milling cutter meaning tends to be sensitive, which provides CNC cutting tool developers with the freedom to choose new CNC machining tools and blade designs. These designs may be optimized. Using new CNC machining tool meaning, it may be better to process the safety, accuracy, surface quality, metal removal rate, CNC machining tool overhang, high-speed cutting, and differential cutting path The strength of the path.

Today’s milling CNC machining tools are constantly optimized to meet the needs of modern manufacturing, machine tools and raw materials, and adopted by all industries. Of all CNC milling cutter products supplied by Sandvik Coleman, about 80% are coromill CNC machining cutters, most of which have been developed in the past 10 years. Compared with the old product, the new CNC machining tool has several times faster metal removal speed, smaller cutting force and better orientation. Its typical runout is only a fraction of that of the old CNC machining tool, so it can always control the machining yamen runner within a smaller boundary, and the cutting edge wear is smaller and more dream. The axial and radial runout are very small, which means that the accuracy of cutting edge is increased, so the surface quality of workpiece is better, yamen service is smaller, the service life of CNC machining tool is longer, and the distribution of cutting load is more average, so as to increase the cutting speed, reduce noise, vibration and wear.

CNC machining tools can also help to increase spindle speed, high-speed feed and hard part milling, and expand the opportunity of dry cutting. The design of these CNC machining tools is more simple, and the amount of work required for adjustment and care is very little. The cutter body is rigid and accurate in size, which is made of pre hardened steel to ensure that the cutter blade is accurately and stably installed on the CNC milling cutter body, and the appropriate pitch can be selected according to the different use scenes.

The new CNC milling cutter uses the blade material and groove type developed for specific raw materials or processes. The function and achievement of the new CNC milling cutter equipped with these blades are far superior to the ISO or ans standard CNC machining cutter and blade. Compared with numerous standard blades, modern new blades and CNC machining tools can provide larger positive rake angle and more complex groove shape, thus reducing cutting force, resulting in faster and more stable synergistic effect of metal removal.

The use of outdated milling CNC cutting tools will bring important consequences to the economic benefits of machining and production safety. If the machining enterprises continue to use the milling CNC cutting tools that have fallen behind the development of new technology, they will gradually lose their manufacturing strength and competitiveness. And if only buy advanced milling machine, but not enough to update CNC machining milling cutter and blade, it’s like a shallow taste, halfway back.

The development of cutting CNC machining tool technology and CNC machining strength, as for those manufacturing enterprises that still use outdated special milling CNC machining tools, boring CNC machining tools or special CNC machining tools, means an increasing potential space. These CNC machining tools are often specially designed and used in the process of a certain part or series of parts, which means that when they are used as the turning CNC machining tools of machining center, any standard on a part needs to be processed with a different CNC machining tool.

Features and principles of die casting die

Application features of die casting die:

1) The metal liquid enters the mold cavity under high pressure and high speed, which causes severe conflict and impact on the surface of the mold cavity, causing corrosion and wear on the surface of the mold.

2) Molten metal in the process of pouring is inevitably brought in by slag, which has complex chemical effect on the surface of forming parts. The compound of aluminum and iron is like a wedge, which accelerates the cause and development of die casting die cracks.

3) Thermal stress is the key reason for the surface cracks of die-casting parts. In the production process of each die-casting, apart from the high-speed and high-pressure erosion of metal liquid, the surface of the formed parts also absorbs the heat released by the metal in the solidification process, which results in heat exchange. Due to the heat conduction of the die material, the temperature of the surface layer of the formed part rises sharply, and there is a large temperature difference between the surface layer and the internal layer, thus the internal stress occurs. When the metal liquid fills the cavity, the surface of the cavity first reaches high temperature and expands, while the inner mold temperature is low and the relative expansion amount is small, which causes the surface pressure stress. After the mold is opened, the surface of the mold cavity contacts with the air, which causes tensile stress due to the cooling of shrinkage air and coating. This kind of alternating stress increases with the continuous production. When the fatigue limit of the die material is exceeded, the surface layer of the die will be plastic deformed and crack will occur.

Selection principle of working temperature of die casting die:

1) The mold temperature is insufficient, the internal structure of the casting is loose, the air is troublesome, and it is difficult to form.

2) The mold temperature is too high, the internal structure of the casting is compact, but the casting is easy to be “welded” and attached to the mold cavity

It is not easy to unload the casting. At the same time, too high temperature will make the mold expand and affect the dimensional accuracy of the casting.

3) The mold temperature should be selected within the appropriate boundary, usually after proper test, thermostatic control is better

The above content is introduced here first. If you have any other questions, please contact us directly. We will serve you wholeheartedly.

A summary of the causes of collision in CNC machining center

When doing CNC machining, we often encounter the problem that machining center collides with the machine, which will not only affect the machining efficiency, but also may destroy the workpiece, more likely to form personal events. So what are the causes of CNC machining center collision?

（1） Cutter compensation input error is a common cause of collision

1. Coordinate offset 60 Li input error

2. Input error such as workpiece coordinate g54

3. Length G43 compensates for H input error or call error

4. Radius G41 compensates for D input error or call error

5. G40 or G49 or g80 input error

（2） Error manipulation

1. Wrong procedure

2. Install the wrong knife

3. Wrong machining coordinates

4. Power on without returning to the original point

5. Handwheel or manual target error

（3） Unique programs can also cause crashes

1. There is more than one tool change in the program (it will collide with the machine due to tool compensation error)

2. The program will return to the cutting point (pressing plate or screw) after cutting at the mechanical reference point

3. The program starts with a slash (Z appears in front of H)

4. Lower safety height (pressing plate or nut)

Do you remember the above reasons? I hope you will pay more attention when you work.

The influence of temperature on the process of precision parts

As for our precision machinery parts processing industry, sufficient accuracy is often a more intuitive reflection of the processing strength of the workshop. We know that temperature is a major factor affecting the processing accuracy. Here is a brief introduction from Xiaobian:

In the process of essential machining, under the action of various heat sources (conflict heat, cutting heat, environmental temperature, thermal radiation, etc.), the temperature change of machine tool, cutter, workpiece to be processed will generate thermal deformation, which will affect the relative displacement between workpiece and cutter, form machining deviation, and then affect the machining accuracy of parts. For example, if the linear expansion coefficient of steel is 0.000012 / ℃, for steel pieces with a length of 100m m, the elongation will be 1.2 μ m when the temperature rises by 1 ℃. In addition to directly affect the expansion and contraction of the workpiece, temperature transformation also has an impact on the accuracy of machine tools and equipment.

In precision machining, higher requirements are put forward for the machining accuracy and the stability of the precision. According to the statistics of related materials, the machining deviation caused by thermal deformation accounts for 40% – 70% of the total machining deviation in the precision machining. Therefore, in the high-precision machining, in order to prevent the expansion and contraction of workpieces due to the temperature change, the reference temperature of the environment is usually strictly regulated, and the deviation boundary of the temperature change is formulated. The constant temperature machining at 20 ℃ ± 0.1 ℃ and 20 ± 0.01 ℃ still appears.

In general, for the constant temperature and humidity test room for precision processing, in order to prevent the expansion and contraction of the processed workpiece due to temperature change during processing and measurement, the reference temperature in the chamber is usually strictly regulated, and the deviation boundary of temperature change is formulated, while the requirements for air relative humidity are not as strict as the accuracy requirements for textile testing. For example, a national ultra precision machining laboratory requires a temperature of 20 ℃ ± 0.2 ℃ and a relative humidity of 45% ± 5%.

In the future, with the development of society and the progress of technology, precision parts processing temperature control technology will be more and more developed.

The principle of CNC process division

There are two different principles that can be used to distinguish CNC process, i.e. process set principle and process distribution principle.

(1) Process set principle

The principle of CNC machining process set is that each process contains as many machining contents as possible, so as to reduce the total number of processes. The principle of CNC machining process set is applicable to the machining of workpieces on high-efficiency special equipment and CNC machine tools. The advantages of selecting the principle of process set are: increasing the production efficiency; reducing the number of processes, reducing the process route, simplifying the production plan and production organization; reducing the basic number, the number of operators and the floor area; reducing the number of workpiece clamping, not only ensuring the mutual position accuracy between the processing surfaces, but also reducing the number of clamps and the auxiliary time of clamping workpiece. However, the investment of CNC processing equipment and industrial equipment is large, it is difficult to adjust and maintain the control, and the production planning cycle is long, which is not conducive to the transfer of production.

(2) Distribution principle of CNC process

Process distribution is to distribute the processing of workpieces in more CNC processes, and the processing content of each process is very little. The principle of CNC processing procedure distribution is applicable to simple processing equipment and process equipment. The advantages of selecting the principle of process distribution are: simple operation of processing equipment and process equipment, simple adjustment and maintenance, and easy conversion to production; it is conducive to selecting the correct cutting amount and reducing the maneuvering time. However, the process route is long, the floor area is large, the number of equipment and workers is large, and the processing accuracy is greatly affected by the skill level of the operators.

Six strict tolerance requirements in CNC precision parts machining

The CNC machining machinists are quite fond of seeing such equipments as + / – 0.005 “, which are the six techniques to maintain strict yamen service requirements in CNC precision parts processing. Five thousandths of an inch is a workout for any good mechanic – they might as well close their eyes and grind. But those jobs are more demanding. Add another zero, now you have: 0.0005 “. Holding five tenths of you is a completely different story. This is the difference between the thickness of a person’s hair and white blood cells. When it comes to strict yamen runner, here are some suggestions to maintain your part specifications.

1. The spindle warms up to maintain the critical tolerance

Run a warm-up program – although it’s a standard program for a lot of CNC machines, it’s more difficult to study and run. A typical program only warms up the spindle, which is essential for applying grease to prevent premature bearing wear. However, you also need to allow internal components to reach a safe operating temperature to cope with thermal expansion. Now, if you only want to maintain strict yamen service on the z-axis, all of these are accurate, but if you integrate the preheating of the spindle with the movement of the machine tool on all the axes, this will help further. The machine is allowed to run for 10-20 minutes, and all parts move to the desired temperature, which will help reduce the impact of thermal expansion of milling time. No matter what, at the end of the warm-up, make sure to measure all the equipment accurately and maintain strict yamen service.

Tool selection may be a factor in maintaining strict government service. Rough machining is carried out with rough machining equipment, so as to reduce the wear of finish machining tools and maintain the accuracy.

2. Equipment selection for maintaining tight yamen service

Choose your equipment carefully – when you deal with these intolerant yamen runners, make sure it is suitable for you. You need to ensure that you have specific equipment for roughing and finishing, so that the roughing tool can receive wear, while the finishing tool only saves one process, so as to ensure the repeatable process of creating accurate parts.

3. Strictly tolerated compensation

Compensation for your equipment – the equipment manufacturers are not happy, so they design the equipment with a little tolerance. They know that if you want to use their equipment to do something, you will be more happy if its reduction performance goes out of too large size instead of too large size. It’s like shaving: you might as well take a rest, but you can’t put it back. Knowing this, you need to make sure that the first thing you do when configuring an accurate job is to dial your essential equipment diameter. You can finish it in many ways, but my preferred way is to mill a feature, and then use accurate equipment to verify the size. Very simple – if you insert a 0.250 inch hole with a 0.236 inch tool, and only a 0.248 inch measuring pin can be inserted, then your tool size will be reduced by 0.001 inch (because the size of each side cannot be small, so use half value).

4. Maintain the temperature of tight yamen service

Thermal stability – this is one of the important things in the list, because it can make a huge difference, and you may not even pay attention to it. Please pay attention to the location of your machinery. Is it close to the window? If so, at some time of the day, is the sunlight reflected on it? Is the air conditioning system started in the afternoon and blowing cool air in the cabin? Are your raw materials stored in a stuffy warehouse, and then enter the cold 68 ° environment? These seem innocent, but will cause huge difficulties in your process. The thermal expansion or contraction of a milling machine or cutting material can vary greatly in your processing. Put all of this in place – keep your machinery and materials in a temperature controlled climate, protected from the sun, and you’ll be rewarded – in the totality of your process.

5. Maintain the calibration of government officials

Calibrate your device – when you’ve done all of the above, all you need is * that * is more stringent, research calls at the manufacturer. After a machine is built, transportation, falling off the truck, moving, stabilizing, using thousands of hours, things will be transferred and handled. This is not preventable. Fortunately, there are several pieces of equipment, whether granite block or Renishaw ballbar, that can help maintain the reins on the loose machinery of the marathon. We like to have a club test and adjust it as part of our annual care so that you can maintain a close relationship with the accuracy of the machine. In the rest, the implementation of these annual services can ensure that the bearings are tight and smooth, the belts are properly tensioned, and the drive motors operate well – these are important factors for accurate machining machinery.

6. Linear scale for maintaining tight government service

If it all fails, scale! – if you still finish all the work on this list, and still try your best, it’s probably time to study using linear scale to obtain machinery. Your typical CNC machine will use the drive motor encoder as the key way to track its absolute position, but this may be due to the shortcomings of the ball screw or the formation of temperature difference. The linear scale changes all of this – usually installed in the workshop, they are composed of two key parts – the scale and the reading head.

Analysis of hardening factors in CNC parts

Many CNC machining enterprises have encountered the problem of hard parts. Next, Xiaobian explains why CNC parts are hard to process. CNC hardware parts processing technology in order to reach the accurate surface of processing parts, it needs to choose the dream processing principle and precise forming activities. But beside the essential work, it is very difficult to finish the accurate machining principle of mechanical numerical control, and there is a big gap between it and the dream value. If we only seek for accurate comments, it will affect the machining efficiency and fail to achieve the expected economic benefits.

The key factors that affect the hardness of CNC parts are as follows:

Factors of raw materials to be processed: the hardness of raw materials to be processed is small, and the more plastic the raw materials are, the more important the level of hard cold working is.

2. The form factor of the tool: the front angle, the edge fillet and the wear amount of the back edge of the CNC machining tool have a great influence on the cold working hard layer. The hardness and depth of the hard layer increase with the decrease of the front angle and the increase of the wear of the edge and the back edge.

The change of cutting speed and feed rate has a great influence on cold work hardness. When the cutting speed increases, the contact time between the cutter and the workpiece is short, the plastic deformation level is small, and the hardness and hard layer are reduced. As the feed speed increases, the plastic deformation level increases, and the surface cold hardening level increases.

Therefore, as long as the correct prevention of the above factors, there will be no problem of CNC machining parts.