September 2020 – Page 19 – CNC Machining & Turning, Milling, Metal parts

Tips for CNC machining

We pay attention to efficiency and quality when we work, so we need some skills to achieve these two points. It is also a very good thing to learn to use some skills when we are processing. In the processing process of CNC machining center, it is very important to avoid collision of CNC machining center when programming and operating processing. Because the price is more expensive. Let’s take a look at what techniques can be used to avoid collisions?

Using computer simulation system

With the development of numerical control system, simulation technology is more and more perfect. Therefore, it can be used in the preliminary inspection procedure to observe the movement of the tool to determine if there is a possibility of collision.

Using the analog display function of CNC machining center

Generally, more advanced CNC machining centers have graphic display function. When the program is input, the graphic simulation display function can be called to observe the motion track of the tool in detail, so as to check whether the tool may collide with the workpiece or fixture

Using the empty running function of CNC machining center

The correctness of the tool path can be checked by using the idle running function of CNC machining center. When the program is input into CNC machining center, the tool or workpiece can be installed, and then press the “empty run” button. At this time, the spindle does not rotate, and the worktable automatically runs according to the program path. At this time, it can be found whether the tool may collide with the workpiece or fixture. However, in this case, it must be ensured that when the workpiece is installed, the tool cannot be installed; when the cutter is installed, the workpiece cannot be loaded, otherwise there will be collision.

Using the locking function of CNC machining center

General CNC machining center has locking function (full lock or single axis lock). When the program is input, the z-axis is locked, and the collision can be judged by the coordinate value of z-axis. The application of this function should avoid the operation of tool change, otherwise the program can not pass.

The setting of coordinate system and cutter compensation must be correct

When starting CNC machining center, the reference point of CNC machining center must be set. CNC machining center working coordinate system should be consistent with the programming, especially the Z axis direction. If there is an error, the possibility of milling cutter and workpiece collision is very large. In addition, the setting of tool length compensation must be correct, otherwise, it is either empty machining or collision.

Machining details of shaft parts

1、 Basic machining route of shaft parts

The main machining situation of shaft parts is the general situation of outer circle and common special shape. Therefore, it is necessary to select the appropriate processing method for bucket force according to the requirements of various Accuracy grades and profile roughness. There are four basic processing routes.

First of all, it is the processing route from rough turning to semi finishing turning, and then to finishing turning, which is also the main process route for the pin cylindrical machining of shaft parts with common materials; The second is from rough turning to semi finishing turning, and then to rough grinding. For ferrous metal materials and parts with high accuracy requirements, general coarseness requirements are small and need to be hardened, this processing route is a good choice for bucket force, because grinding is an ideal subsequent processing procedure for bucket force; The three routes are from rough turning to semi finishing turning, then to finishing turning and diamond turning. This kind of processing route is specially used to process non-ferrous materials. Because the hardness of non-ferrous metals is small, it is easy to block the gap between sand grains. If grinding is used, it is not easy to obtain the required profile roughness, so finish turning and diamond turning must be adopted; The latter processing route is from rough turning to semi finishing turning, then to rough grinding, fine grinding and finishing. This route is often used for the parts which are hardened by ferrous metal and have high requirements for precision and low requirements for coarseness value.

2、 Pre machining of shaft parts

Before turning the outer circle of shaft parts, some preparatory procedures should be carried out, which is the pre machining process of shaft parts. Straightening is an important preparatory process. Because the workpiece blank in the manufacturing, transportation and storage process, often occurs bending deformation. In order to ensure reliable clamping and uniform distribution of machining allowance, straightening is carried out by various presses or straightening machines in cold state.

3、 Positioning datum for machining shaft parts

First of all, the center hole of the workpiece is used as the positioning reference for machining. In the machining of shaft parts, the general situation of each outer circle, the coaxiality of taper hole and thread profile, and the verticality of the end facing torsion axis are all important appearance of position accuracy. These profiles are generally based on the center line of the shaft as the design basis, positioning with the center hole, and the principle of appropriate datum coincidence. The center hole is not only the positioning datum in turning, but also the locating datum and grinding datum of other machining processes. When two center holes are used for positioning, multiple outer circles and end faces can be machined in one clamping process.

Secondly, the outer circle and the center hole are used as the positioning datum. This method effectively overcomes the error and fallacy of poor rigidity of the central hole positioning, especially when machining heavy workpieces, the positioning of the central hole will cause unstable clamping and the cutting parameters can not be too large. If the outer circle and the center hole are used as the positioning datum, there is no need to worry about this problem. In rough machining, the general situation of the shaft’s outer circle and a central hole are used as the positioning reference, which can bear a large cutting torque in the machining, which is a common positioning method for shaft parts.

The third is to take the general situation of two outer circles as the positioning datum of machining. When machining the inner hole of the hollow shaft, the center hole can not be used as the positioning reference, so the general situation of the two outer circles of the shaft should be used as the positioning reference. When machining machine tool spindle, two supporting journal is often used as positioning reference, which can effectively ensure the coaxiality requirement of taper hole relative to supporting journal, and eliminate the error caused by the non coincidence of datum.

The cone plug with a central hole is used as the positioning reference for machining. This method is widely used in the processing of hollow shaft cylindrical profile.

4、 Clamping of shaft parts

The machining of cone plug and cone sleeve mandrel must have high machining accuracy. The center hole is not only the positioning reference for manufacturing itself, but also the datum for finishing the outer circle of hollow shaft. It is necessary to ensure that there is a high coaxiality between the cone surface and the central hole on the cone plug or cone sleeve mandrel. Therefore, when selecting the clamping mode, attention should be paid to reduce the installation times of the cone plug as far as possible, so as to reduce the repeated installation error of the parts. In actual production, the cone plug installation in the future, generally speaking, before the completion of processing, will not be removed or replaced in the middle of processing

CNC machining scope

The direct meaning is to say that it is computer digital control. It is a kind of processing technology commonly used in the manufacturing industry at present. It can also be said that it is the symbol of the current manufacturing industry. CNC machining center is mainly used to finish multi axis linkage processing easily. For example, the processing of curved surface is almost impossible if it is separated from CNC and processed by ordinary machine tools.

CNC machining center focuses on the processing of some careful spare parts, mainly used in automobile and motorcycle accessories, lighting lamps, automatic robots, mechanical hardware, aerospace military industry, electronic instruments, medical equipment, 3C digital, household appliances, communication mobile phone and other industries.

The materials processed by CNC machining center usually include ABS, PC, PE, POM, PP, PMMA, nylon, bakelite, silicone rubber, aluminum alloy, zinc alloy, magnesium alloy, titanium alloy, steel, copper, stainless steel, sheet metal and other raw materials.

The order process of CNC machining center is: 1. Order plan customization; 2. Disassembly and programming; 3. Material preparation; 4. CNC processing; 5. QC inspection; 6. Surface treatment; 7. QC quality inspection; 8. Delivery of molding products

Hardware processing should be done

The requirements of hardware processing are very high. Although we often carry out the processing work, we have to meet the standards for the quality of products and their own safety and work efficiency. So today, we will learn what things must be done in the hardware processing?

1、 All employees should check whether their clothes meet the work requirements before entering the work. Slippers, high-heeled shoes and clothes that affect safety are not allowed. Those with long hair should wear safety helmets. Keep correct posture when working, have enough spirit to deal with the work. If you feel unwell, you should leave the post immediately and report to the leader. During operation, it is necessary to concentrate on the operation, and it is strictly prohibited to chat and cooperate with each other. The operator should not operate under the state of irritability and fatigue, so as to avoid accidents and ensure the safety of operation.

2、 Before the machine works, check whether the moving part is filled with lubricating oil, and then start and check whether the clutch and brake are normal, and run the machine tool at idle speed for 1-3 minutes. It is strictly forbidden to operate in case of mechanical failure.

3、 When replacing the mold, the power supply should be turned off first, and the moving Department of the punch should stop running before the mold can be installed and debugged. After installation and adjustment, manually move the flywheel for two times to check whether the upper and lower dies are symmetrical and reasonable, whether the screws are firm, and whether the blank holder ring is in a reasonable position.

4、 Only when all other personnel leave the mechanical working area and take away the sundries on the worktable, can the power supply be started to start the machine.

5、 After the machine is started, one person will transport materials and operate the machine. Other people are not allowed to press the electric building or step on the pedal switch board, nor can they put their hands into the mechanical working area or touch the moving parts of the machine with their hands. When the machine is working, it is forbidden to reach into the slider working area, and it is forbidden to take and place the workpiece by hand. The standard tools must be used when taking and placing the workpiece in the die. In case of abnormal sound or machine failure, the power switch should be turned off immediately for inspection.

6、 When off duty, the power supply should be turned off and the finished products, leftovers and sundries should be sorted out to ensure the clean and safe working environment

Tools for bakelite processing

Corn milling cutter is suitable for cutting this kind of brittle plastic, and the cross section is very flat.

A milling cutter is a rotary cutter with one or more teeth for milling. When working, the cutter teeth cut off the allowance of the workpiece intermittently in sequence. Milling cutter is mainly used for machining plane, step, groove, forming surface and cutting workpiece on milling machine.

Cylindrical milling cutter

It is used for machining plane on horizontal milling machine. The cutter teeth are scattered on the circumference of the milling cutter, and can be divided into straight teeth and spiral teeth according to the tooth shape. According to the number of teeth, it can be divided into coarse teeth and fine teeth. Spiral tooth rough tooth milling cutter has less teeth, high tooth strength and large chip holding space, which is suitable for rough machining; fine tooth milling cutter is suitable for finishing.

Face milling cutter

Also known as disk milling cutter, it is used for machining plane on vertical milling machine, end milling machine or gantry milling machine. There are cutter teeth on the end face and circumference, and there are coarse teeth and fine teeth. There are three kinds of structures: integral, inlaid and indexable.

end mill

It is used for machining groove and step surface. The cutter teeth are on the circumference and end face, and can not feed along the axial direction. When the end mill has end teeth passing through the center, it can be fed axially.

Three side edge milling cutter

It is used for machining various grooves and step surfaces, with cutter teeth on both sides and circumference.

Angle milling cutter

There are two kinds of single angle milling cutter and double angle milling cutter for milling groove with definite angle.

Saw blade milling cutter

It is used for machining deep groove and cutting workpiece. There are many cutter teeth on its circumference. In order to reduce the conflict during milling, there is a 15 ′ ~ 1 ° offset angle on both sides of the cutter teeth. For the rest, there are keyway milling cutter, dovetail groove milling cutter, T-groove milling cutter and various form milling cutter.

T-shaped milling cutter

It is used for milling T-groove.

Improper processing of CNC

In the process of processing, every step is very important. If one step is not in place due to carelessness in the process of processing, it is likely to directly affect the final effect of the product. Therefore, in the process of work, the operator must maintain a full state of mind, which is not only for their own good, but also has good results for the product, so if the CNC processing technology is not properly arranged, what problems will occur?

CNC machining process is too scattered

The reason for this problem lies in the fear of complexity (refers to the preparation time), simple programming, simple operation and processing, easy adjustment of tool setting by using a knife, and being used to ordinary processing. As a result, the product quality (position tolerance) is not easy to guarantee and the production efficiency can not be brought into full play. Therefore, CNC processing personnel and operators should be fully familiar with CNC machining knowledge, try more to master the relevant knowledge, as far as possible to use the method of process concentration for processing, more use, will naturally reflect its advantages. After two sets of equipment are used, the processing efficiency is greatly improved and the equipment quality is greatly improved.

CNC machining sequence is unreasonable

Some CNC processing operators consider some problems in preparation, and often arrange the processing sequence irrationally. NC machining is usually carried out according to the requirements of general machining process planning, such as coarse to fine (tool change), inside to outside, reasonable cutting parameters, so that the quality and efficiency can be improved

Advantages of CNC lathe and automatic lathe

Large CNC lathe is a kind of high precision and high efficiency automatic machine tool. It adopts the method of machining parts and cutter displacement controlled by computer programming. Automatic lathe processing is an automatic machine tool with cam cutter. The machining is completely controlled by the cam. So what are the advantages of large CNC lathe and automatic lathe?

1。 The number of molds is greatly reduced, and complex molds are not needed to process parts with complex shapes. If you want to change the shape and size of a part, you only need to modify the part processing.

2。 The machining quality is stable, the machining precision is high and the repetition precision is high.

3。 Under the condition of multi variety and small batch production, the production efficiency is high, and the time of production preparation, machine tool adjustment and process inspection is reduced. And reduce the cutting time because the number of cuts is used.

4。 It can process complex profiles which are difficult to be processed by traditional processing methods, and even some parts that cannot be observed.

Advantages of automatic lathe processing:

1。 The processing speed is fast. In the process of automatic lathe processing, the tool carrier moves and processes at the same time, so that the processing speed of automatic lathe is 4-6 times faster than that of numerical control lathe.

2。 The processing cost is low. The price of automatic lathe equipment is lower than that of numerical control lathe, the processing speed is fast, and the processing cost is lower than that of numerical control lathe.

Advantages and disadvantages of CNC machining aluminum alloy

What is the significance of CNC processing of aluminum alloy profiles? The popular point is that CNC machining is the use of computer to program processing programs, such as cutting, tapping, tapping, counterbore, etc., basically relying on numerical control operation. Aluminum alloy CNC processing of alloy profiles can reduce product damage, so what are the advantages and disadvantages of CNC processing of aluminum alloy? Let’s take a look at it

The products with good use are easy to use and difficult to use. The advantage of CNC machining is that it can reduce the processing times. As long as the program is modified, complex aluminum profiles can be processed without complex tools. The processed aluminum profile has high precision and stable quality. Whether it is the traditional aluminum profile, the complex cross-section of different materials, or the parts with poor machining, CNC machining is operable.

Disadvantages of NC machining: processing equipment is more expensive, and the quality requirements of operators are relatively high.

Advantages and disadvantages of CNC machining of aluminum profiles

CNC machining is CNC machine tool processing, that is, a set of processing program is compiled by computer, and the article is processed by digital milling machine. The same is true for CNC processing of aluminum profiles. Including cutting, drilling, tapping and so on, basically depends on CNC operation. CNC processing can reduce the damage rate of products, which is favored by aluminum profile manufacturers.

Advantages: ① greatly reduce the number of tooling, complex processing forms of parts do not need complex tooling. If we want to change the form and size of parts, we only need to modify the part processing program, which is applicable to the development and modification of new products.

② The machining quality is stable, the machining precision is high, and the repeated precision is high, which is suitable for the processing requirements of aircraft.

③ It can reduce the time of production planning, machine tool adjustment and process inspection, and reduce the cutting time due to the use of good cutting amount.

④ It can be used to machine the complex surface which is difficult to machine by conventional way, and even can process some parts which cannot be observed.

The disadvantage is that the processing equipment is relatively high, and the quality requirements of operators are high.

CNC machining center maintenance

CNC is also called computer gong, cncch or CNC machine tool. In fact, it was introduced into the Pearl River Delta of mainland China. It is actually a CNC milling machine. In Guangzhou, Jiangsu, Zhejiang and Shanghai, a new type of machining technology is called CNC machining center. Its main work is to compile processing programs, that is, to convert the original manual work into computer programming. So what are the basic conditions for Dongguan CNC machining center maintenance?

1、 Basic conditions of maintenance personnel in CNC machining center

The quality of repair work depends on the personnel condition. It is necessary for repair workers to have the following basic conditions: a high sense of responsibility and outstanding professional ethics; a wide range of knowledge, grasp the basic knowledge of computer skills, analog and digital circuits, automatic control and motor drive, inspection skills and mechanical processing technology and a certain level of foreign language; through outstanding skills training, master the work of CNC, drive and PLC Professional principle, understand CNC programming and programming language; understand the structure, have experimental skills and strong ability to operate; grasp a variety of commonly used (especially on-site) testing instruments, appearance and various maintenance tools.

2、 The conditions of CNC machining center maintenance methods

Prepare common spare parts and accessories; get practical assistance or supply of micro electronic components at any time; repair necessary things, instruments, appearance, wiring and microcomputer. The best way is to have a small programming system or programmer to assist equipment debugging; complete materials, manuals, circuit diagrams, repair instructions (including CNC operation instructions), interface, adjustment and diagnosis, driver instructions, PLC instructions (including PLC user program list), component forms, etc.