March 2020 – Page 4 – CNC Machining & Turning, Milling, Metal parts

On the commonly used fixture materials

Common fixture / fixture materials: (A3, 45, P20, Cr12MoV, S136, SKD11, tungsten steel)

These raw materials are used for making fixtures and jigs, but different raw materials have different uses. Each raw material has different characteristics. Let me make a general comment on the usage of each raw material;

1. A3, 45, cheap raw materials, usually used in the main board without auxiliary fixture;

2. P20, Cr12MoV, usually an important part of the fixture, because the selected raw materials can be wear-resistant, will strengthen the service life of the product, and ensure the application accuracy;

3. S136 raw materials, mainly for wear and rust resistance. Generally used in welding fixture is a common raw material;

4. SKD11 raw materials are usually used in inspection tools and some sophisticated and wear-resistant tools;

5. Tungsten steel, the raw material used less, because the cost of raw materials is quite expensive, usually used in a thorough inspection tool, mainly if wear-resistant and rust proof high;

What kind of influence will be caused to the parts when CNC machining is very rough

This article will introduce the influence of rough machining on CNC parts

1. Influence on wear resistance: the rougher the CNC product processing surface, the smaller the useful contact area between mating surfaces, the greater the pressure, the greater the conflict resistance, and the faster the wear.

2. Affect the stability of fit: for clearance fit, the coarser the surface is, the easier it is to wear and make the middle gap gradually increase in the working process; for interference fit, because the meso convex peak is squeezed flat when it is equipped, the essential useful interference is reduced and the connection strength is reduced.

3. Influence on fatigue strength: there are large grooves on the surface of rough parts, which are the same as sharp corner notches and cracks, and are sensitive to stress sets, thus affecting the fatigue strength of parts.

4. Impact on corrosion resistance: rough part surface is easy to make corrosive gas or liquid penetrate into the inner layer of metal through the surface micro concave Valley, forming surface erosion.

Kunshan CNC processing

5. Influence on sealing: rough surfaces can not be well fitted, and gas or liquid leaks through cracks between contact surfaces.

6. Influence on contact stiffness: contact stiffness is the strength of the part fusion surface to resist contact deformation under the action of external force. The stiffness of the machine depends on the contact stiffness between the parts to a great extent.

7. Affect the measurement accuracy: the surface roughness of the measured surface of the part and the measuring surface of the measuring equipment will directly affect the measurement accuracy, especially in the careful measurement.

Other factors, such as coating, thermal conductivity and contact resistance, reflection strength and radiation function, flow resistance of liquid body and smooth current on conductor surface, will be affected by surface roughness at different levels. Therefore, Suzhou CNC processing plant should pay close attention to this aspect, and do not make the same mistakes in the production process.

How to reduce the scrap rate of parts in precision machining

How to reduce the scrap rate of workpiece in precision machining? I hope I can help you with the understanding of precision workpiece processing.

In the process of precision machining, the design of workpieces should be correct. In the process of design, we should study whether the processing is simple, whether the process and requirements meet the nature of the workshop and market supply. Precision machining enterprises need to provide improved equipment, high-precision processing equipment and inspection equipment. In terms of material use, it is also important to calculate the required raw materials, process placement, and processing methods for each workpiece, and comply with strict process requirements.

In precision machining, the first step of the processing staff is to see the technical requirements of the drawings clearly. It is the basic of precision machining to follow the process. Check whether the drawings of the parts are intact and accurate, and analyze whether the accuracy, surface integrity and technical requirements of the key surfaces of the parts can be reached under the existing manufacturing conditions. Therefore, in time-honored and wonderful machining experience, some people with machining experience may also reduce the scrap rate of workpieces.

To sum up, see through the technical requirements of the drawing; follow the process processing; select the appropriate speed feed; accurately select the tool angle; process the workpiece cutting amount to meet the requirements to complete the processing mission; accurately use all kinds of measuring tools, and follow the strict process requirements. The quality of products is the key to the success or failure of enterprises, so it is not too late to reduce the scrap of precision machining parts and improve the quality of workpieces for every precision machining plant.

After the above understanding of precision workpiece processing, I hope to be able to help you.

The identification rule of coordinate direction for CNC machine tools

In order to simplify the way of programming for CNC machining and ensure the exchange of recorded data. The naming of the coordinates and targets of CNC machine tools has been formulated in the world for a long time. Jb3051-82 “naming of coordinates and targets of CNC machine tools” was formulated in 1982 in China.

In the CNC machining rules, the right-hand Cartesian coordinate system is selected to name the coordinate system of the machine tool. X, y and Z are used to represent the linear feed coordinate axis, and the relationship between X, y and Z coordinate axes is decided by the right skill:

The circular feed coordinate axis rotating around the X, y and Z axes is represented by a, B and C. according to the right-hand spiral rule, the targets of + A, + B and + C are confirmed, as shown in the figure.

Some of the feeding activities of CNC machine tools are completed by the spindle to start the cutter activities, some by the worktable with the workpiece activities. In normal programming, no matter whether the machine tool moves during machining or the workpiece is still moved, if the workpiece to be machined is relatively stationary, and the cutter is moving, and the object that the cutter is far away from the workpiece is the positive target Z axis of the coordinate coincides with the axis of the spindle, and the object that the cutter is far away from the workpiece is the positive target (+ Z); The x-axis is perpendicular to the Z-axis and parallel to the clamping surface of the workpiece. If it is a single column milling machine, the right moving target is the positive target (+ x) of the x-axis when facing the tool spindle to the column target; the y-axis can be confirmed according to the selected x-axis and z-axis according to the right technique..

How to improve precision machining?

Facing the penetration of high-tech such as artificial intelligence and big data into mechanical parts processing enterprises, the traditional precision mechanical parts processing plants are more distant. On the one hand, a large number of people are still not allowed to learn CNC parts processing and programming from scratch. On the other hand, these skills are brilliant, but it is difficult to land them. If a mechanical parts processing factory wants to invest in these skills, it may lose all its energy and cause the previous achievements to be wasted.

Now, precision machine parts processing plant is facing a big dilemma, that is, the profit margin is too low and the technology content is lower. The workshop of machine parts processing is still the traditional assembly line. In such a production mode, the new generation of employees are also defined as equipment and cost, and the subjective initiative cannot be developed. The old model is really out of date, and the new generation of employees are more and more disgusted with these mechanical work. Therefore, the automatic and intelligent machining of mechanical parts is highly sought after in order to completely free the hands of human beings. The manufacturing of some large products, such as automobiles and home appliances, is still basically automated. However, the manufacturing of Zhihao mobile phones, iPads and other products requires high precision. If the current automation equipment is unable to correctly install a soft cable, it is still necessary to ask for help In precision machine parts processing plant.

What should be paid attention to in the processing of non-standard fixture accessories

The following points should be paid attention to for grinding of non-standard fixture accessories:

1. Abrasive grain size for grinding shall be changed from coarse to fine in sequence. When changing abrasives, the grinding trace of the previous process should be completely removed. Grinding should be carried out until the grinding trace can only be seen this time. It is very important to prevent the “relief” phenomenon by punching the thimble.

2. The abrasive of the same size can only be used for the same grinding tool. Before changing the size, the workpiece must be completely cleaned to prevent coarse abrasive or other dirt from being brought to the next process to form scratch on the grinding surface.

3. Each time the next grain size is changed, the grinding shall be carried out at an angle of 30-45 ° with the last grinding target. If there are deep scars, it is not allowed to only grind the one-sided position, otherwise, the one-sided position will be pitted, and full trimming shall be carried out to remove the pit. It is necessary to pay attention to average grinding for simple grinding and not simple grinding stations

These are the articles shared today. Do you understand? If you want to know more about or need non-standard fixture accessories, please call our company or pay attention to our official website. We will sincerely serve you.

How to maintain CNC machine

The key point of prevention and maintenance of CNC machine tools is to strengthen daily maintenance, which includes daily inspection, weekly inspection, monthly inspection, quarterly inspection and semi annual inspection. CNC machining CNC machine tool prevention * * maintenance details are as follows:

1. Daily inspection of CNC machine tools

Its key items include hydraulic system, spindle smooth system, guide rail smooth system, cooling system and air pressure system. Daily inspection is based on the normal condition of each system. For example, when testing the process of the spindle smooth system, the power light should be on, and the oil pressure pump should operate normally. If the power light is not on, the spindle stop mode should be maintained, which is related to the mechanical engineer. Carry out repairs.

2. Weekly inspection of CNC machine tools

Its key items include machine parts and spindle smooth system, which should be inspected accurately every week. The unique thing is to eliminate iron chips and remove external sundries for machine parts.

3. Monthly inspection of CNC machine tools

If the main power supply and air dryer for inspection. Under normal conditions, the rated power supply voltage is 180v-220v, and the frequency is 50Hz. If there is any exception, measure and adjust it. The air dryer shall be disassembled once a month, and then washed and equipped.

4. Quarterly inspection of CNC machine tools

The quarterly inspection should focus on three aspects: machine bed, hydraulic system and spindle smooth system. For example, when inspecting the machine bed, it is important to see whether the accuracy and level of the machine meet the requirements of the manual. If there is any problem, it should be related to the mechanical engineer as soon as possible. When inspecting the hydraulic system and the spindle smooth system, if there is any problem, the new oil 6ol and 20L should be exchanged and washed.

5. Semi annual inspection of CNC machine tools

Half a year later, the hydraulic system, spindle smooth system and x-axis of the machine tool should be inspected. If there is any defect, the new oil should be replaced, and then the washing work should be carried out. After fully understanding and taking charge of the knowledge of prevention and protection, we must have a deeper understanding and necessary management of the causes and handling of the extra phenomena of the oil pressure system. For example, when the oil pump does not inject oil, the pressure is abnormal, there is noise and other phenomena, we should know what the key reasons are and what the corresponding treatment methods are.

The reason and treatment of the unusual phenomenon of oil pressure system should be understood from three aspects

(1) The key reasons for oil pump not to inject oil may include low liquid level in oil tank, reverse rotation of oil pump, insufficient rotation speed, high oil viscosity, low oil temperature, filter congestion, too large volume of oil suction pipe, air suction at oil inlet, damage of shaft and rotor, etc. there are corresponding treatment methods for key reasons, such as filling oil, confirming label, changing when oil pump reverses, etc.

(2) Abnormal pressure means high or low pressure. There are many reasons for this, such as improper pressure setting, bad coil behavior of pressure regulating valve, abnormal pressure gauge, leakage of oil pressure system, etc. The corresponding treatment methods include dismantling and washing according to the pressure configuration of the articles of association, replacing a normal pressure gauge, and checking in sequence according to each system, etc.

(3) Noise is mainly caused by oil pump and valve. When there is noise in the valve, the reason is that the flow exceeds the rated standard, so the flow shall be adjusted properly; when there is noise in the oil pump, there are many reasons and corresponding treatment methods, such as high oil viscosity and low oil temperature, the treatment method is to raise the oil temperature; when there is bubble in the oil, the air in the system shall be discharged, etc.