2020 – Page 73 – CNC Machining & Turning, Milling, Metal parts

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.

Five links of plastic mold

First, effective management of product data management, process data management, drawing document management: effective mold product data management, process data management, drawing document management, can ensure the comprehensiveness of the file, the consistency of the drawing version; so that the drawings can be effectively shared and effectively used for query. It can establish a complete file management computer database to collect and use the design drawings, scattered, previously scattered and isolated information accumulated by the design department, so as to prevent problems caused by the design drawings, 2D and 3D confusion, confusion of original, design change, maintenance version, inconsistency of 3D model and 2D drawing data, and nonstandard and chaotic design of 2D drawings Find out and correct in time, cause the mold to be modified, reworked, even invalid, increase the manufacturing cost of the mold, lengthen the manufacturing and production cycle of the mold, and affect the delivery time.

Second, keep the consistency and integrity of plastic mold drawings, processing technology and physical data: ensure the consistency and integrity of mold drawings, processing technology and physical data through effective, meticulous and strict detection means.

Third, the design and manufacturing cost of each set of plastic mold must be summarized in time: through the effective control of the issuance of the workshop work order, effective management of tool scrap; Through accurate mold structure design, efficient mold parts processing and accurate parts detection, the additional cost of mold due to design change and maintenance will be effectively reduced, so as to obtain the actual cost of each set of mold and effectively control the mold quality.

Fourth, overall planning: organically organize and integrate the planning, design, processing technology, workshop production, human resources and other information, so as to effectively coordinate the planning and production, and effectively ensure the quality of plastic mold and timely delivery.

Fifth, develop a complete and practical plastic mold production management system: develop a complete mold production management system, realize the computer information management system of product data management, process data management, plan management and schedule management of mold production management process, including plastic mold production plan formulation, mold design, process formulation, workshop task assignment and Product inspection, warehouse management, etc., so that mold manufacturing and related auxiliary information from planning to completion delivery can achieve a full range of tracking management.

Precautions for plastic mold

1、 Don’t just focus on product design, ignore plastic mold manufacturing.

Some users in the development of products or trial production of new products, often focus on product development and development at the initial stage, ignoring the communication with the plastic mold production unit. After the product design scheme is preliminarily determined, there are two advantages to contact the mold manufacturer in advance:

1. It can ensure that the designed product has a good forming process, and it will not modify the finalized design because the parts are difficult to process.

2. The mold maker can make design preparation in advance to prevent improper consideration in a hurry and affect the construction period.

3. To make high quality plastic mould, only when the supplier and the demander cooperate closely can the cost be reduced and the cycle be shortened.

2、 Don’t just look at the price, but consider the quality, cycle and service in an all-round way.

1. There are many kinds of molds, which can be roughly divided into ten categories. According to different requirements of part material, physical and chemical properties, mechanical strength, dimensional accuracy, surface finish, service life, economy, etc., different types of die forming are selected.

2. The die with high precision needs to be processed by high precision CNC machine, and the die material and forming process are strictly required. CAD / CAE / CAM die technology is also needed to design and analyze.

3. Some parts have special requirements when forming, and the mold also needs to use advanced technology such as hot runner, gas assisted molding, nitrogen cylinder, etc.

4. The manufacturer shall have CNC, EDM, WEDM and CNC profiling milling equipment, high-precision grinder, high-precision three coordinate measuring instrument, computer design and relevant software, etc.

5. Generally, large stamping dies (such as automobile covering dies) should consider whether the machine tool has a blank holder mechanism, even edge lubricant, multi position progressive and so on. In addition to the punching tonnage, the punching times, feeding device, machine tool and die protection device should be considered.

6. The manufacturing means and process of the above mould are not possessed and mastered by every enterprise. When choosing a cooperative manufacturer, we must know its processing ability, not only from hardware equipment, but also from management level, processing experience and technical force.

7. For the same set of mould, there is sometimes a big gap in the quotation of different manufacturers. You should not pay more than the value of the mold, but also should not be less than the cost of the mold. Mold manufacturers, like you, should make reasonable profits in business. Ordering a set of molds with a much lower price will be the beginning of trouble. Users should start from their own requirements and measure them comprehensively.

3、 Avoid multiple cooperation, try to make plastic mold and products processing.

1. With a qualified mold (qualified test piece), it is not necessarily possible to produce a batch of qualified products. This is mainly related to the selection of machining machine tools, forming process (forming temperature, forming time, etc.) and the technical quality of operators.

2. With a good mold, but also have a good forming process, the best is one-stop cooperation, try to avoid multi cooperation. If the conditions are not met, it is necessary to select a party who is fully responsible and write clearly at the same time.

Why do two-color mold products appear gray and black spots?

1. The cycle time is short, that is to say, the residual time of molten material in the barrel is short and the cycle time is prolonged.

2. The barrel temperature in the feeding area is too high, which reduces the barrel temperature in the feeding area.

3. Screw speed is too fast, reduce screw speed.

4. Screw back pressure is too low, increase screw back pressure.

In addition, the reason related to the design of the two-color mold is that the unreasonable screw geometry selects the screw with a long feeding section, and the screw groove of the feeding section is deep.

If the measurement process of the two-color mold injection process starts too early, and the air wrapped in the particles in the screw feeding area does not overflow the feeding port, the air will be squeezed into the melt. However, the pressure in the feeding area is too low to move the air to the rear. The air squeezed into the molten material in the barrel will cause grey black spots in the products. Just like what happens in the compression ignition diesel engine, the coking phenomenon caused by the air squeezed into the barrel is sometimes called “diesel engine effect”. The coking phenomenon can explain the high temperature produced by compression at the junction of the molten material and the extruded bubble, and the fracture of the molten material caused by the oxidation of oxygen in the air. The melting process should be started in the middle of the feeding area when the injection process of the two-color mold is debugged, where the melting pressure is high, forcing the air between the particles to move backward and overflow the material mouth.

The preferred apparent gray black markings may occur near the gate, in the middle of the runner and away from the gate. This phenomenon can only be seen in transparent parts, and is often found in two-color mold injection products made of PMMA, PC and PS materials.

All kinds of machine tools in machining

With the development of industrial modernization, the processing and manufacturing of various parts are gradually from manual processing to mechanical processing. The development in the middle is rather tortuous. The first to realize mechanization is the textile industry in ancient China. The loom was the first processing equipment to replace the manual at that time. But in the stage of capitalist development, the industrial revolution in Britain rose because of the steam engine, and the machines in various industries of the steam engine were invented one after another. Later, the refining of oil promoted the development of engines, more mechanical products were produced one after another, and the operation speed and efficiency of machinery were greatly improved. Later, with the gradual improvement of electromagnetic theory, generators were also produced, and human beings began to use electricity, and various industries were booming. To the modern computer and other intelligent products operation and calculation has replaced a lot of human heavy work, the development of the machinery industry has also appeared the situation of the whole machinery. Baoding Honglian machine roll Co., Ltd. introduces the operation principle and development of various machine tools in detail.

The main processing in the mechanical processing industry includes turning, milling, planing, grinding and boring. But now the machining center basically contains these machining. The so-called turning is lathe machining, which uses the rotation movement of chuck and the feed movement of turning tool to cut workpiece. It mainly cuts some circular axis and symmetrical workpiece, and the machining accuracy is greatly improved. Milling is the most important machining method in mechanical processing. It processes the workpiece surface through the rotation and feed motion of milling cutter. Now, the diversification of milling machine adds more technology to milling. Both planer and grinder are used for planing and grinding the plane, groove and other processing surfaces of the workpiece to achieve a smoother and smoother surface. Boring machine is similar to drilling machine in hole processing, which is also essential in mechanical operation..

Features of sheet metal parts

1. Sheet metal has the characteristics of light weight, high strength, conductive (can be used for electromagnetic shielding), low cost, large-scale mass production performance and so on. At present, sheet metal has been widely used in the fields of electronic appliances, communication, automobile industry, medical devices and so on. For example, in computer case, mobile phone, MP3, sheet metal is an essential part.

2. With the application of sheet metal more and more widely, the design of sheet metal parts has become a very important part in the process of product development. Mechanical engineers must master the design skills of sheet metal parts, so that the designed sheet metal can not only meet the requirements of product function and appearance, but also make the stamping die manufacturing simple and low cost.

3. Sheet metal is sometimes used as trigger gold. The word comes from English sheet metal. Generally, some sheet metal is pressed by hand or die to produce plastic deformation, forming the desired shape and size, and further forming more complex parts by welding or a small amount of machining, such as the chimney, tin furnace, and car shell are sheet metal parts.

4. Modern sheet metal technology includes: filament power winding, laser cutting, heavy processing, metal bonding, metal drawing, plasma cutting, precision welding, roll forming, metal plate bending forming, die forging, water jet cutting, precision welding, etc.

Advantages of copper zinc alloy in sheet metal processing

Among the materials of sheet metal processing, copper has many outstanding physical and chemical properties. For example, its thermal conductivity and conductivity are very high, its conductivity is second only to silver, and its thermal conductivity is second only to silver and gold. Chemical stability is strong, easy to dissolve, in the atmosphere, fresh water, sea water has a good corrosion resistance.

Copper zinc alloy, the color changes from yellow red to yellow with the increase of zinc content. The mechanical properties of brass are higher than that of pure copper, and it will not rust or be corroded under the same conditions. It has good plasticity and is widely used in the mechanical manufacturing industry to make various structural parts.

Moreover, it has high plasticity and can bear all kinds of cold and hot pressure sheet metal processing well. The disadvantage is that the strength and hardness are low. Generally, it does not make structural parts. Pure copper is also known as red copper, which is light rose or light red. After the copper oxide film is formed on the surface, its appearance is purple red

Source of sheet metal processing

Sheet metal processing is sometimes used for pulling metal processing. Generally, some metal sheets are pressed by hand or die to produce plastic deformation, forming the desired shape and size, and further forming more complex parts through welding or a small amount of machining, such as the chimney commonly used in the family, tin furnace, and automobile shell are sheet metal parts. Sheet metal processing is called sheet metal processing. For example, using plates to make chimneys, iron buckets, oil tanks, ventilation pipes, elbows, Tianyuan places, funnel-shaped and so on. The main processes are cutting, bending and buckling, bending and forming, welding, riveting and so on, which requires certain geometric knowledge. Sheet metal parts are sheet metal parts, which can be processed by stamping, bending, stretching and other means. A general definition is the parts with constant thickness in the process of processing. The corresponding parts are casting parts, forging parts, machining parts, etc. for example, the outer iron shell of the car is sheet metal parts, and some cabinets made of stainless steel are sheet metal parts..