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

Introduction of two color mold

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.

Test standard before CNC machining

Inspection standard before processing:

1. After the completion of each middle division, first copy the work coordinates, and then check whether the distance from the center to both sides is the same again after clearing, so as to ensure that the middle division and the reading are correct.

2. Select, install, set and read the coordinates of Z axis. Select the appropriate tool according to the programming list, clean the tool head and the nozzle thoroughly before installing the tool, and check whether the tool is skewed with the calibration table after installing the tool. Check again after reading

Check once to avoid wrong knife and wrong number, which will cause great loss to the company.

3. Transfer program, start machining: use single section to execute before cutting, adjust the transfer speed and feed speed to the slowest speed, lower the cutter slowly, watch the machine tool display Z axis allowance, check if there is any abnormality, press the pause key immediately if there is any abnormality, and find out the original

To solve the problem, confirm that everything is normal and adjust to the right speed to start processing.

4. In the process of machining, pay attention to observe whether the machining is abnormal, whether the cutter is worn or not. If the cutter is seriously worn, pause the grinding to ensure the normal machining.

Select the tool type according to the shape of the machined profile

For concave surface, in semi finishing and finishing, the ball head cutter should be selected to obtain good surface quality, but in rough machining, the flat end end end milling cutter or round end milling cutter should be selected, because the cutting conditions of the ball head cutter are poor; for convex surface, the flat end milling cutter or round end milling cutter is generally selected in rough machining, but the round end milling cutter should be selected in finish machining, because of the circle The geometric condition of angle milling cutter is better than that of flat end milling cutter; for the side with demoulding inclination, taper milling cutter should be selected. Although the bevel can be processed by interpolation with flat end milling cutter, the machining path will be longer and the machining efficiency will be affected, and the tool wear will be increased and the machining accuracy will be affected.

Precautions for CNC machining

1. The rotating speed of white steel knife shall not be too fast.

2. The copper cutter uses less white steel knife and more throwing knife or alloy knife.

3. When the workpiece is too high, it should be cut thick with different lengths of knives in layers.

4. Smooth the knife only when the margin is consistent. After the big knife is used for roughening, use the small knife to remove the surplus material.

5. The plane shall be processed with flat bottom knife and less spherical knife to reduce the processing time.

6. When the copper worker cleans the corner, first check the size of R on the corner, and then determine the size of the ball knife.

7. The four corners of the surface shall be level.

8. Where the slope is integer, it shall be processed with slope cutter, such as pipe position.

9. Before each working procedure, think about the surplus left after the previous working procedure, so as to avoid empty cutter or excessive machining.

10. Try to take a simple cutting path, such as contour, trenching, single side, less surround height.

11. When walking wcut, if you can walk finish, don’t walk rough.

12. When the shape of a smooth knife is smooth, it should be rough first, then fine. When the workpiece is too high, it should be smooth first, then the bottom.

13. Set tolerance reasonably to balance machining accuracy and computer calculation time. The tolerance is set to 1 / 5 of the allowance when opening rough, and to 0.01 when smoothing.

14. Do more processes to reduce the time of empty cutting. Think more and reduce the chance of mistakes. Do a little more auxiliary line auxiliary surface to improve the processing condition.

15. Establish a sense of responsibility and carefully check each parameter to avoid rework.

16. Be diligent in learning, good at thinking and continuous improvement.

Milling non plane, more ball knife, less end knife, do not be afraid to receive knife.

The small knife cleans the corner, the big knife is refined;

Don’t be afraid to mend the surface. Proper mending can improve the processing speed and beautify the processing effect.

High hardness of blank material: better reverse milling

Low hardness of blank material: good milling

Good accuracy, rigidity and finish machining of machine tool: it is more suitable for down milling and vice versa

It is strongly recommended to use down milling for the finishing of internal corners of parts.

Rough machining: better reverse milling, finish machining: better forward milling

Good toughness and low hardness of tool material: suitable for rough machining (machining with large amount of cutting)

Poor toughness and high hardness of tool material: suitable for finishing (machining with small cutting amount)

Analysis of the market development prospect of stationery dichroism

The survey report shows that the prospect of China’s stationery market is broad, which is obvious to all, but only brand stationery with high product quality and innovative design can obtain higher added value. According to the survey report, 72.5% of consumers are not only interested in the main functions of the product, but also in other auxiliary functions.

For example, the best-selling heteromorphic pens are the representatives. The head of Shanghai golden crown golden pen marketing department said: “at present, there are many kinds of heteromorphic pens in the market, and their functions are more and more diversified, and their creativity is more and more amazing. Crayons, modeling pens, feather pens, fruit pens, gear pens Just listening to these names is new. Nowadays, pens are not only simple pens, but also toys and even works of art. Besides students, adults also like these new things very much. Another important sales channel of these irregular pens is gifts and gifts from enterprises and institutions. ”

In today’s Internet era, the traditional four treasures of study are being replaced by keyboard and mouse, but pen is still an important working tool in the hearts of many business people, and it has become an essential personal item for people who are really familiar with life art. Some top-level commemorative pens are designed by famous teachers with the latest technology, exquisite craftsmanship, precious raw materials, and relying on the commemorative social themes, which are of great collection value and ornamental value.

The performance advantages of Chinese mould

1. Small density: the density of plastic is small, which is of great significance for reducing the weight of mechanical equipment and energy saving, especially for vehicles, ships, aircraft and spacecraft.

2. High specific strength and specific rigidity: the absolute strength of plastic is not as high as that of metal, but the density of plastic is small, so the specific strength (σ B / ρ) and specific rigidity (E / ρ) are quite high. In particular, reinforced plastics made of various high-strength fibrous, flaky and powdery metals or nonmetals as fillers have higher specific strength and stiffness than metals.

3. Good chemical stability: most plastics have good acid, alkali, salt, water and gas resistance. Under normal conditions, they do not react with these substances.

4. Good electrical insulation, thermal insulation and acoustic insulation.

5. Good wear resistance and self lubrication: plastic has small friction coefficient, good wear resistance, good self lubrication, high specific strength and low transmission noise. It can work effectively in liquid medium, semi dry or even dry friction conditions. It can be made into bearings, gears, cams, pulleys and other machine parts, very suitable for low speed, small load occasions.

6. Strong adhesion.

7. Good molding and coloring performance.

Operation process and precautions of CNC milling machine

1、 Purpose

In order to improve the company’s efficiency and ensure the delivery time of parts processing, this document is hereby formulated in a unified and standardized way of operation.

2、 Scope of application

It is suitable for company computer gong operator.

3、 Responsibilities and authorities

1. Daily cleaning and maintenance work, training for users, correct operation of computer gongs and machine tools.

Job content:

2. Clamping method and tool use standard before processing:

1) Press strip, vise, magnetic table, fixture, select the best clamping method according to the applicability of the workpiece.

2) Bead: pay attention to the cleaning of the burr and iron chips on the plane of the machine and the adjustment of the height of the bead, so as to avoid the collision between the knife arm and the bead.

3) Vise: pay attention to the cleaning and clamping force of the fixed and movable surfaces of the vise.

4) Magnetic table: when using the magnetic table, it is necessary to consider whether the bottom of the workpiece is flat, whether the adsorption surface is large enough, and whether the workpiece edge processing pad is blocked. In order to ensure that the process will not be loose.

2. Inspection standard before processing:

1) After the completion of each division, first copy the work coordinates, and then recheck whether the distance from the center to both sides is the same after clearing, to ensure that the division and reading are correct.

2) Select, install, set and read the coordinates of Z axis. Select the appropriate tool according to the programming list, clean the tool head and the nozzle thoroughly before installing the tool, and check whether the tool is skewed with the calibration table after installing the tool. Check again after reading the knife to avoid the wrong knife, which will cause great loss to the company.

3) transmit program and start processing: use single section execution before cutting tool, transfer speed and feed speed to slowest, slow down knife, watch machine tool display Z axis margin, check abnormal, if abnormal, press the pause button immediately, find out cause, solve abnormal, confirm all normal, adjust to suitable speed to start processing.

4) In the process of machining, always pay attention to observe whether there is abnormal machining, whether the cutter is worn or not. If the cutter is seriously worn, pause the grinding to ensure the normal machining.

3. Processing standard of core

1) After getting the drawing and workpiece, first check whether the drawing and workpiece mold number are consistent.

2) Measure the actual size of the workpiece with a measuring tool.

3) Check whether the direction of water transportation and reference angle on the 2D drawing is consistent with that on the programming list.

4) Use 400 × oilstone to clean the burr at the bottom and around of the workpiece, and use cloth chips to clean the workpiece.

5) Place the workpiece on the clamping tool of the machine platform, level the plane and perpendicularity of the workpiece with the parallelism, and the perpendicularity tolerance is within ± 0.015. Then fix the workpiece firmly and start the centring. According to the position indicated on the programming list, divide the centring and z-axis collision number. (pay attention to whether the edge finder collides with the workpiece during the split) input the data of the mechanical coordinates x, y and Z into the corresponding coordinates.

6) Transfer all the programs into the computer according to the programming list, use the tool path simulation software to simulate, check the processing area and the maximum and minimum depth of processing, and determine the clamping direction, clamping reservation position and tool length of the workpiece.

7) Install the corresponding tool according to the programming list, and input the tool parameters automatically with the method of automatic tool setting.

8) Transfer the program to the machine for processing.

4. Copper processing standard

1) After getting the program sheet, find the appropriate copper material by comparing the mold number on the program sheet with the size and quantity of copper material.

2) According to the requirements of the programming list, process the rough and the young. (to avoid common mistakes of coarse and young materials, the copper material is marked with a code, “a” for young male, “B” for coarse male.

4) Check if the tool on the program sheet matches the tool on the machine magazine. The program is simulated with the tool path simulation software, and the machining area, the maximum and minimum machining depth are observed to determine the clamping direction, reserved position and the length of the tool.

5) Transfer the program to the machine for processing. In the process of workpiece processing, the next workpiece to be machined must be prepared to reduce the above preparation time.

5. Formwork processing standard

1) After the workpiece is processed, check whether the shape of the workpiece is consistent with the shape of the 3D drawing before dismounting, and then check whether the workpiece has the position of missing processing, over cutting and smooth connection at the junction.

2) According to the data marked on the programming list, use the calibration table or depth gauge to measure the accurate number, and use the needle gauge or plug gauge to measure some matching positions and positioning positions.

3) Measuring parting surface: according to the data provided by the drawing or programming personnel, check the coordinates of several points (x, y, z) on the parting surface, and check whether the parting surface has been machined to the number.

4) Measure whether the depth of all horizontal positions reaches the number. For some positions that need to be connected, first improve the processing, and then paint the color on the connected positions and then slowly connect them.

5） Check the position data of all other requirements for CNC machining accuracy, and confirm that it is OK before getting off the machine.

6. Precautions:

1) Take extra care when removing the tool from the tool holder to avoid scratching your fingers.

2) When using the numerical control program that has not been tried out, the machine cannot be operated fully automatically.

3) When the shaft is still rotating, use extreme care to adjust the coolant flow direction.

4) In case of emergency, press the red emergency switch on the controller.

What is two color injection molding

Double injection molding is mainly used to produce two-color products by two material tubes of double color molding machine and two sets of molds.

Compared with traditional injection molding, dual material co injection molding process has the following advantages:

1. The core material can use low viscosity material to reduce the injection pressure.

2. In consideration of environmental protection, the recycled secondary materials can be used as the core materials.

3. According to different use characteristics, for example, soft material is used for thick finished leather material, hard material is used for core material or foamed plastic can be used for core material to reduce weight.

4. Lower quality core materials can be used to reduce costs.

5. Coating material or core material can be used with high price and special surface properties, such as anti electromagnetic interference, high conductivity and other materials to increase product performance.

6. The proper combination of the core material and the cortex material can reduce the residual stress of the products, increase the mechanical strength or the surface properties of the products.

7. Products that produce lines like marble.

From the characteristics and application of multi-color injection molding and dual material co injection molding, it can be seen that there is a trend to gradually replace the traditional injection molding process in the future. The innovative injection molding technology not only improves the precision of the injection molding process, provides the high difficulty process technology, but also opens up the scope of the injection molding process field. The innovative injection equipment and process are enough to meet the more diverse, high-quality and high value-added product demand.

Two color injection molding has been widely used in electronic products, electric tools, medical products, home appliances, toys and almost all plastic fields. The production and molding of two color mold, the research and development of two color multi-color injection molding machine and two color injection raw materials have also made rapid development.

Operation rules of computer milling machine

Basic information of computer gong processing

1. When you enter the workshop for practice, you should wear work clothes, tie the big cuff tightly, and tie the shirt into the pants. Female students should wear safety helmets and incorporate braids into the helmets. Sandals, slippers, high heels, vests, skirts and scarves are not allowed to enter the workshop. Note: it is not allowed to operate the machine tool with gloves;

2. Be careful not to move or damage the warning signs installed on the machine tool;

3. Pay attention not to place obstacles around the machine tool, and the working space should be large enough;

4. If two or more people need to complete a certain work together, they should pay attention to the coordination and consistency between each other;

5. Compressed air is not allowed to clean the machine tool, electrical cabinet and NC unit;

6. The internship shall be conducted on the designated machine tool and computer. Without permission, other machine tools, tools or electrical switches shall not move randomly;

Preparations for computer gong processing

1. Before operation, you must be familiar with the general performance, structure, transmission principle and control program of CNC milling machine, and master the function and operation program of each operation button and indicator light. Do not operate and adjust the machine tool until you understand the whole operation process.

2. Before starting the machine tool, check whether the electrical control system of the machine tool is normal, whether the lubrication system is unblocked, whether the oil quality is good, and add enough lubricating oil according to the specified requirements, whether the operating handles are correct, whether the workpiece, fixture and cutter are firmly clamped, and whether the coolant is sufficient. Then start the idle car for 3-5 minutes, check whether the transmission parts are normal, and confirm that there is no fault After that, it can be used normally.

3. After the completion of the program debugging, it must be approved by the instructor before the step-by-step operation, and skip step execution is not allowed. Without the permission of the instructor, operate without permission or in violation of regulations. If the result is zero, the accident will be punished according to relevant regulations and the corresponding loss will be compensated

4. Before machining parts, it is necessary to strictly check whether the original point of the machine tool and the data of the cutting tool are normal and carry out the simulation operation without cutting path.

Precautions for computer gong processing

1. When processing parts, the protective door must be closed, and it is not allowed to stretch the head and hand into the protective door, and it is not allowed to open the protective door during processing;

2. During the processing, the operator shall not leave the machine tool without permission, and shall keep a high concentration of ideas and observe the operation state of the machine tool. In case of any abnormal phenomenon or accident, the program operation shall be terminated immediately, the power supply shall be cut off and the instructor shall be informed in time, and other operations are not allowed;

3. It is strictly prohibited to pat the control panel and touch the display screen. It is forbidden to knock the workbench, dividing head, clamp and guide rail;

4. It is forbidden to open the control cabinet of CNC system for viewing and touching without permission;

5. The operator shall not change the internal parameters of the machine tool at will. Students are not allowed to call or modify other programs not compiled by themselves;

6. On the machine tool control microcomputer, no other operation is allowed except for program operation and transmission and program copy;

7、 CNC milling machine belongs to large precision equipment. Except for the tools and workpieces placed on the workbench, it is strictly prohibited to stack any tools, clamps, blades, measuring tools, workpieces and other sundries on the machine tool;

8. It is forbidden to touch the tip of the knife and the iron scraps by hand. The iron scraps must be cleaned with an iron hook or a brush;

9. Do not touch the rotating spindle, workpiece or other moving parts by hand or any other means;

10. It is forbidden to measure the workpiece and change the speed manually in the process of processing, not to wipe the workpiece with cotton thread or clean the machine tool;

11. No trial operation;

12. When using the hand wheel or fast moving mode to move the position of each axis, be sure to see clearly the signs of “, -” in each direction of X, y, Z axis of the machine tool before moving. When moving, first turn the hand wheel slowly to observe whether the moving direction of the machine tool is correct before speeding up the moving speed;

13. When it is necessary to suspend the measurement of workpiece size during the operation of the program, the measurement can only be carried out after the machine tool stops completely and the spindle stops running, so as to avoid personal accidents;

14. If the machine tool is not used for several days, the NC and CRT parts shall be electrified for 2-3 hours every other day.

15. When the machine is shut down, it can only be shut down after the spindle stops for 3 minutes.

Structure of plastic mould

The utility model mainly includes a die with a variable cavity composed of a die combination base plate, a die assembly and a die combination card plate, and a die with a variable core composed of a die combination base plate, a die assembly, a die combination card plate, a cavity cutting assembly and a side cutting combination plate. Coordinate change of punch, die and auxiliary forming system. It can process series plastic parts of different shapes and sizes.

In order to improve the properties of plastics, it is necessary to add a variety of auxiliary materials, such as fillers, plasticizers, lubricants, stabilizers, colorants, etc., in order to become plastics with good properties.

1. Synthetic resin is the most important component of plastics, its content in plastics is generally 40% – 100%. Because of its high content and the properties of resin often determine the properties of plastics, people often regard resin as a synonym of plastics. For example, PVC resin and PVC plastic, phenolic resin and phenolic plastic are confused. In fact, resin and plastic are two different concepts. Resin is a kind of raw polymer, which is not only used to make plastics, but also used as raw materials for coatings, adhesives and synthetic fibers. In addition to a very small part of plastics containing 100% resin, the vast majority of plastics, in addition to the main component resin, also need to add other substances.

2. Filler is also called filler. It can improve the strength and heat resistance of plastics, and reduce the cost. For example, adding wood powder to phenolic resin can greatly reduce the cost, make phenolic plastic one of the cheapest plastics, and significantly improve the mechanical strength. Fillers can be divided into organic fillers and inorganic fillers, the former is wood powder, rags, paper and various fabric fibers, the latter is glass fiber, diatomite, asbestos, carbon black, etc.

3、 Plasticizer plasticizer can increase the plasticity and softness of plastics, reduce brittleness, and make plastics easy to process and shape. Plasticizers are generally high boiling point organic compounds that can be miscible with resins, non-toxic, odorless, light and heat stable, and the most commonly used ones are phthalates. For example, in the production of PVC plastics, if more plasticizers are added, soft PVC plastics can be obtained. If no or less plasticizers are added (dosage < 10%), rigid PVC plastics can be obtained.

4. Stabilizer in order to prevent the decomposition and damage of the synthetic resin by light and heat in the process of processing and use, and to extend the service life, stabilizer should be added to the plastic. Commonly used stearate, epoxy resin, etc.

5. Colorant colorant can make plastics have all kinds of bright and beautiful colors. Organic dyes and inorganic pigments are often used as colorants.

6. The function of lubricant is to prevent the plastic from sticking to the metal mold when it is forming, and to make the plastic surface smooth and beautiful. Commonly used lubricants are stearic acid and calcium magnesium salt. In addition to the above auxiliaries, flame retardant, foaming agent and antistatic agent can also be added to the plastic.