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

Analysis on the technical problems of CNC machining electrical board

The most common CNC processing Bakelite in China can be done by blowing air. Use tungsten steel knife or PCD knife. Do not use white steel knife to rotate too fast to 1-10 meters. Moreover, when processing, pay attention to chip removal or the chips will be piled on the workpiece, the large plate-shaped workpiece will be deformed due to unclean treatment, of course, the product will also be deformed after a period of time, mainly affected by the temperature and humidity.

Do not use coolant when processing electrical board with China CNC. If coolant is used in the processing, the chips cut by it are easier to block the water pump. If you want to have a better cooling effect and make sure that there is no smoke everywhere in the workshop, it is good to use air mist to cool, but remember not to use water. Add antirust cutting fluid to the water to protect the machine tool from rust. If you want to process products with high flatness, you must use vacuum sucker. Of course, poor quality bakelite, serious deformation. Poor color hair weight, odor when cutting, easy to layer not delicate.

Analysis on the technical problems of CNC processing electric board in China:

The most common way to process Bakelite is to blow. Tungsten steel knife or PCD knife are used. White steel knife is not allowed. Do not rotate too fast. Feed 1-10 meters, (mainly depends on the power of the spindle, the diameter of the cutter, and the cutting depth. Generally, 3-4 meters is suitable. ）In addition, when processing, pay attention to chip removal, otherwise the chip will pile on the workpiece, the large plate-shaped workpiece will be deformed, of course, the product will be deformed after a period of time, mainly affected by temperature and humidity.

When using CNC computer gong to process electrical board, do not use coolant. If coolant is used in the process, the chips cut by it will be broken and water pump will be blocked easily. If you want to have a better cooling effect and make sure that there is no smoke everywhere in the workshop, it is good to use air mist to cool, but remember not to use water. Add antirust cutting fluid to the water to protect the machine tool from rust.

If you want to process products with high flatness, you must use vacuum sucker. Of course, poor quality bakelite, serious deformation. Poor color and heavy hair, stink when cutting, easy to layer, not delicate. This requires that when purchasing, we must choose manufacturers with better quality to purchase electrical boards.

CNC machining center integrates into the mobile world

CNC machining center has been successfully integrated into the mobile world. In fact, people and intelligent terminals have been integrated, and each node is more accurate and efficient information interaction.

As we all know, in addition to work and sleep, we also have a lot of fragmented time every day. The existence of these fragmented time and the popularity of current smart phones make the mobile Internet industry hot. Fengge said that in the era of Internet development, CNC machining center will march into the mobile Internet, promote its own new products as an important channel for mobile Internet to publicize its own products, and effectively attract its own target customers through such a mode. Consumers will search information more actively according to their own initiative needs, so as to achieve the goal of enterprises and enterprises The interaction between consumers has achieved a new height of mobile marketing.

CNC machining center is one of the most productive and widely used CNC machine tools in the world. It has strong comprehensive processing ability, can complete more processing content after the workpiece is clamped once, and has high processing accuracy. For the batch workpiece with medium processing difficulty, its efficiency is 5-10 times of that of ordinary equipment, especially it can complete the processing that many ordinary equipment cannot complete. It is more suitable for the single piece processing with complex shape and high precision requirements or the production of multiple varieties with small and medium batches. Feng Ge, an expert in the industry, knows a lot about CNC professional knowledge, keeps up with the trend of the times and the current Internet industry. She believes that an enterprise must keep up with the trend of the times, conform to the development of the times and catch up with the pace of the times. With the rise of China’s e-commerce and the rapid development of the industry, CNC processing centers must take advantage of the trend to transform in order to play the number Control the advantages of machining center.

A new round of enterprise marketing revolution has been triggered. Mobile marketing has become a new highlight of CNC machining center industry. Online marketing has expanded the current market, increased new users, and increased the integrity of products. This way will also give full play to the advantages of products. The irreplaceable advantages of CNC machining center in market capacity, market price and other aspects will be in this marketing mode Next, keep showing. How can enterprises adapt to the new changes? According to industry expert Feng Ge, the realization of online and offline marketing mode is the key to help enterprises adapt to the changes of the times and head-on walk in the front of the industry. The traditional industry CNC machining center is eager to take advantage of the situation to achieve transformation, in order to obtain greater development space.

Six basic problems to be considered in CNC machining

Generally, the workpiece processed by computer gongs has complex shape, many working procedures and many kinds of cutting tools. It is often necessary to complete the whole process from rough machining, semi finish machining to finish machining after one clamping. So the program is more complex. Consider the following when programming.

1. Carefully analyze the drawings and determine the reasonable process route.

2. The size and specification of the tool shall be selected, and the measured actual size shall be filled into the tool card.

3. Determine reasonable cutting parameters. It mainly includes spindle speed, back draft, feed speed, etc.

4. There should be enough space for automatic tool change to avoid collision with workpiece or fixture. It is recommended to set the tool change position at the machine origin.

5. In order to facilitate the inspection and debugging of the program, the processing contents of each step can be arranged in different subprograms, while the main program mainly completes the tool change and subroutine call. This procedure is simple and clear.

6. Check and test run the programmed program, and pay attention to whether there is interference between tools, clamps or workpieces. When checking the m, s and t functions, it can be carried out under the z-axis locking state.

Six basic actions of fixed cycle in CNC machining center

he fixed cycle of computer gong processing center is generally composed of six movements:

Action 1 – x-axis and y-axis positioning: make the cutter quickly position to the hole machining position.

Action 2 – break to R point: the tool feeds rapidly from the initial point to R point.

Action 3 – hole machining: the action of hole machining is performed in the way of cutting feed.

Action 4 – hole bottom action: including pause, spindle quasi stop, tool shift and other actions.

Action 5 return to R point: select r point when the hole processing can be continued and the tool can be moved safely.

Action 6 return to the initial point: generally, the initial point shall be selected after the hole processing is completed.

Brief introduction of positioning and clamping of CNC machining center workpiece

（1） Selection of positioning datum for CNC machining center

(1) Try to select the design datum on the part as the positioning datum.

(2) One clamping can complete the processing of all key precision parts.

(3) When the machining center not only processes the datum but also completes the machining of each station, the selection of its positioning datum needs to consider completing as many machining contents as possible.

(4) When the positioning datum and design datum of the part are difficult to coincide, the assembly drawing shall be carefully analyzed to determine the design function of the design datum of the part. Through the calculation of the dimension chain, the tolerance range between the positioning datum and the design datum shall be strictly specified to ensure the machining accuracy.

（2） Selection and use of fixture in CNC machining center

(1) According to the characteristics of machine tools and machining needs of machining centers, the commonly used fixture types are special fixture, combined fixture, adjustable fixture, group fixture and workpiece unified benchmark positioning fixture system.

(2) The high flexibility of machining center requires that the fixture is more compact and simple than the general machine tool, the clamping action is more rapid and accurate, the auxiliary time is reduced as far as possible, the operation is more convenient, labor-saving and safe, and the sufficient rigidity and flexibility are ensured. Therefore, pneumatic and hydraulic clamping devices are often used.

(3) In order to keep the workpiece fully exposed to all the surfaces to be processed in this positioning and clamping, the clamp shall be as open as possible, and the space position of the clamping element shall be low or low, so there must be space for the tool movement path.

(4) Considering the minimum distance between the spindle and the worktable and the clamping length of the tool, the installation position of the fixture on the worktable of the machine tool shall ensure that the processing content of the workpiece can be completed within the range of the spindle travel.

(5) It is not allowed to interfere with fixture or workpiece during automatic tool change and worktable exchange.

(6) Sometimes, the positioning block on the fixture is used when installing the workpiece. In the process of processing, in order to meet the requirements of the processing of front and rear left and right stations and prevent interference, the workpiece can be removed after being clamped. Therefore, it is necessary to consider how to maintain the positioning accuracy of the workpiece after removing the positioning elements.

(7) Try not to change the clamping point in the middle of processing.

（3） CNC machining to determine the best position of parts on the machine tool table

What are the characteristics of CNC machining center

CNC machining center is a CNC machine tool with tool library and automatic tool change device, which has the comprehensive functions of CNC boring, milling and drilling machine.

CNC machining center has good processing consistency and economic benefits. Compared with other CNC machine tools, it has the following characteristics:

1. The processing of workpiece is complex and the process flow is very long. It can eliminate the human interference factors in the process flow and has high production efficiency and quality stability.

2. Because of the centralized working procedure and the automatic tool change device, the workpiece can complete the complex processing of milling, drilling, boring, expanding, reaming, tapping and so on with the accuracy requirements after one clamping.

3. When there is an automatic exchange worktable, when one workpiece is processed, the other worktable can realize the clamping of workpiece, thus greatly reducing the auxiliary time and improving the processing efficiency.

4. The larger the tool capacity, the wider the machining range, and the higher the flexibility program.

CNC machining center common instruction programming

Many instructions often used by machining centers are the same as those of CNC machine tools, which will not be described here. Only some instructions reflecting machining center features are described below:

1. Accurate stop verification instruction G09

Instruction format: G09;

It can be used for machining parts with sharp edges and corners.

2. Tool offset setting command G10

Instruction format: g10p_ R_ ;

P: Command offset number; R: offset

Tool offset can be set by program setting.

3. Single direction positioning command G60

Instruction format: G60 x_ Y_ Z_ ;

10. Y and Z are the coordinates of the end point to be accurately located.

For hole machining that requires precise positioning, using this command can make the machine tool realize single direction positioning, so as to eliminate the machining error caused by reverse clearance. The positioning direction and overshoot are set by parameters.

4. Precise stop verification mode command G61

Instruction format: G61;

This instruction is modal instruction. In G61 mode, it means that every program contains G09 instruction.

5. Continuous cutting mode command G64

Instruction format: G64;

This command is a modal command and also the default state of the machine tool. After the tool moves to the end of the command, it will not slow down and continue to execute the next program segment, which will not affect the positioning or verification in G00, G60 and G09. G64 is used to cancel G61 mode.

6. Automatically return reference point instructions G27, G28, g29

(1) Return reference point verification instruction G27

Instruction format: G27;

10. Y and Z are the coordinate values of the reference point in the workpiece coordinate system, which can check whether the tool can be positioned on the reference point.

Under this command, the commanded axis moves back to the reference point quickly, decelerates automatically and makes positioning inspection at the specified coordinate value. If it is positioned to the reference point, the signal light of the axis reference point will be on; if it is inconsistent, the program will check again.

(2) Automatic return to reference point instruction G28

Instruction format: G28 x_ Y_ Z_ ;

10. Y and Z are coordinate values of intermediate point, which can be set arbitrarily. The machine moves to this point first and then returns to the reference point.

The intermediate point is set to prevent movement interference with workpiece or fixture when the tool returns to the reference point.

Example: N1 G90 x100.0 y200.0 z300.0

N2 G28 x400.0 y500.0; (middle point is 400.0500.0)

N3 G28 z600.0; (the middle point is 400.0500.0600.0)

(3) Automatically return g29 from reference point

Instruction format: g29 x_ Y_ Z_ ;

10. Y, Z are the returned end coordinates

In the return process, the tool moves from any position to the middle position determined by G28, and then moves to the end point. G28 and g29 are generally used in pairs, and G28 and G00 can also be used in pairs.

For example, as shown in Figure 5-7, after machining, the tool has been positioned to point a (100170), point B (200270) is taken as the middle point, and point C (500100) is the point to be reached when g29 is executed. The procedure is as follows:

G91 G28 X100. 0 Y100.0;

M06;

G29 X300.0 Y-170.0;

Precautions for wire cutting

1. Before starting the machine, check whether the electrical parts are loose. If there are broken wires and parts falling off, inform the professional personnel in time for maintenance.

2. Check the tension of molybdenum wire.

3. Check whether the guide wheel is damaged and change the position of the working face in time to prevent the molybdenum wire from being broken.

4. Check if there is a communication slot in the wire stopper, adjust the position of the working face in time to prevent the molybdenum wire from being broken.

5. Check that the lubricating part of the machine tool has enough lubricating oil.

6. Daily maintenance:

6.1. Add No.30 engine oil once per shift for transverse feed gearbox and longitudinal feed gearbox.

6.2. Each drive shaft, screw rod nut and guide plate of the screw storage barrel shall be added with 30 engine oil once for each plate.

Routine maintenance of CNC lathe

1. Clean and lubricate each guide rail surface every day. For machine tools with automatic lubrication system, regularly check and clean the automatic lubrication system, check the oil volume, add lubricating oil in time, and check whether the oil pump starts and stops regularly.

2. Check whether the automatic lubrication system of the spindle box works normally every day, and change the lubricating oil of the spindle box regularly.

3. Check whether the cooling fan in the electrical cabinet works normally, whether the air duct filter screen is blocked, and clean the dust.

4. Pay attention to check the cooling system, check the liquid level, add oil or water in time, and replace and clean the dirty oil or water.

5. Pay attention to check the main shaft drive belt and adjust the tightness.

6. Pay attention to check the tightness of guide rail insert strip and adjust the clearance.

7. Pay attention to check whether the oil pump in the oil tank of the hydraulic system of the machine tool has abnormal noise, whether the height of the working oil level is appropriate, whether the indication of the pressure gauge is normal, and whether the pipeline and all joints have > leakage.

8. Pay attention to check whether the guide rail and machine tool protective cover are complete and effective.

9. Pay attention to check the mechanical accuracy of all moving parts to reduce the deviation of shape and position.

10. Clean the machine tool, clean the iron scraps and wipe the cooling liquid at the guide rail every day after work to prevent the guide rail from rusting

Processing customized two-color plastic mold for daily necessities

Two color mold: two kinds of plastic materials are injected on the same injection molding machine, which are divided into two parts, but the product is only molded once. Generally, this kind of molding process is also called double material injection molding, which is usually completed by a set of molds and requires a special two-color injection molding machine. At present, the two-color mold is becoming more and more popular in the market. This process can make the appearance of the product more beautiful and easy to change colors without spraying, but the cost is expensive and the technical requirements are high.

1. The two shapes of the master mold are different, forming one product respectively, while the two shapes of the male mold are exactly the same.

2. After the front and back dies of the die rotate 180 o in the center, they must match. This inspection must be done in the design, which requires high positioning processing of the mold base.

3. The total thickness of front formwork panel plus a plate shall not be less than 170mm. Please carefully check other reference data of this type of injection molding machine, such as maximum mold thickness, minimum mold thickness, Ko hole distance, etc.

4. The nozzle of the three plate mold should be designed to automatically demould. Pay special attention to the demoulding action of the soft rubber nozzle.

5. When designing the master mold for the second injection molding, in order to avoid the second master mold inserting (or wiping) to damage the rubber position of the first molded product, part of the master mold can be designed to avoid air. However, the strength of each sealing position must be carefully considered, i.e. in injection molding, is there any possibility of plastic deformation under large injection pressure, leading to the possibility of batch front in the second injection molding?

6. During injection molding, the product size of the first injection molding can be slightly larger, so that it can be pressed more tightly with another male mold during the second molding, so as to achieve the sealing effect.

7. Pay attention to whether the flow of plastic will impulse the products that have been molded for the first time during the second injection molding, so as to deform the glue position? If this is possible, we must find ways to improve.

8. Before closing the A and B plates, pay attention to whether the front mold slider or inclined roof will reset first and crush the product? In this way, we must find a way to make the A and B plates close the mold first, and then the slider or inclined roof of the front mold can be reset.

9. The water transport layout of the two female and male formworks shall be as sufficient as possible, and shall be balanced and the same.

10.99% of the cases are that the hard part of the product is injected first, and then the soft part of the product is injected. Because soft rubber is easy to deform.