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  • 2022.04.11

    Mold material selection requirements

    Mold material selection requirements Mold material selection is a very important link in  Auto parts Mould the entire mold making process. The selection of mold materials needs to meet three principles. The mold meets the work requirements such as wear resistance and toughness, the mold meets the process requirements, and the mold should meet economic applicability. Condition requirements 1. Wear resistance When the blank is plastically deformed in the mold cavity, it both flows and slides along the surface of the cavity, causing severe friction between the surface of the cavity and the blank, resulting in the failure of the mold due to wear. Therefore, the wear resistance of the material is one of the most basic and important properties of the mold. Hardness is the main factor affecting wear resistance. In general, the higher the hardness of the mold parts, the smaller the amount of wear and the better the wear resistance. In addition, wear resistance is also related to the type, quantity, shape, size and distribution of carbides in the material. 2. toughness Most of the working conditions of the mold are very bad, and some often bear a large impact load, which leads to brittle fracture. In order to prevent sudden brittle fracture of mold parts during operation, the mold must have high strength and toughness. The toughness of the mold mainly depends on the carbon content, grain size and organizational state of the material. 3. Fatigue fracture performance During the working process of the mold, fatigue fracture is often caused under the long-term action of cyclic stress. Its forms include small-energy multiple impact fatigue fracture, tensile fatigue fracture, contact fatigue fracture and bending fatigue fracture. The fatigue fracture performance of the mold mainly depends on its strength, toughness, hardness, and the content of inclusions in the material. 4. High temperature performance When the working temperature of the mold is higher, the hardness and strength will decrease, resulting in Household appliances Mould early wear of the mold or plastic deformation and failure. Therefore, the mold material should have high anti-tempering stability to ensure that the mold has high hardness and strength at working temperature. 5. Thermal fatigue resistance Some molds are in a state of repeated heating and cooling during the working process, which causes the surface of the cavity to be subjected to tension, pressure and stress, causing surface cracking and peeling, increasing friction, hindering plastic deformation, and reducing dimensional accuracy, resulting in Mold failure. Hot and cold fatigue is one of the main forms of failure of hot work dies, and these dies should have high resistance to cold and heat fatigue. 6. Corrosion resistance When some molds such as plastic molds are working, due to the presence of chlorine, fluorine and other elements in the plastic, strong corrosive gases such as HCI and HF are decomposed after heating, which erodes the surface of the mold cavity, increases its surface roughness, and aggravates wear failure.

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  • 2022.04.06

    Requirements and characteristics of mold design and production

    Requirements and characteristics of mold design and production The requirements of mold design and production are: accurate size, smooth surface; reasonable structure, high production efficiency, easy to automate; easy to manufacture, long life, low cost; design meets process needs, economical and reasonable. Mold structure design and parameter selection must consider factors such as rigidity, orientation, unloading mechanism, positioning method, and gap size. The wearing parts on the mold should be easy to replace. For plastic molds and die-casting molds, it is also necessary to consider a reasonable gating system, the flow state of the molten plastic or metal, and the location and direction of  Auto parts Mould Plant entry into the cavity. In order to improve productivity and reduce runner casting loss, multi-cavity molds can be used, and multiple identical or different products can be completed simultaneously in one mold. High-efficiency, high-precision and long-life molds should be used in mass production. The stamping die should use a multi-position progressive die:and a cemented carbide insert progressive die can be used to improve the service life. In small batch production and trial production of Household appliances Mould Plant new products, simple molds with simple structure, fast manufacturing and low cost should be used, such as combined die, sheet die, polyurethane rubber die, low melting point alloy die, zinc alloy die, superplastic alloy die, etc. The mold has begun to use computer-aided design (CAD), which is to optimize the design of the mold through a complete computer-centric system. This is the development direction of mold design. According to the structural characteristics, the mold manufacturing is divided into a flat blanking die and a cavity die with a space. The punching die uses the size of the punch and the die to fit precisely, and some even have no clearance fit. Other forging dies such as cold extrusion dies, die casting dies, powder metallurgy dies, plastic dies, rubber dies, etc. belong to cavity dies, which are used to form three-dimensional workpieces. Cavity molds have size requirements in the three directions of length, width and height, and the shape is complex and difficult to manufacture. Mold production is generally single-piece and small-batch production. The manufacturing requirements are strict and precise, and most sophisticated processing equipment and measuring devices are used. The plane blanking die can be initially formed by EDM, and then the accuracy can be further improved by forming grinding, coordinate grinding and other methods. Shape grinding can be done with an optical projection curve grinder, or a surface grinder with a miniature and grinding wheel mechanism, or with a special shape grinding tool on a precision surface grinder. Coordinate grinder can be used for precise positioning of molds to ensure precise hole diameter and hole spacing. It can also use a computer numerical control (CNC) continuous trajectory coordinate grinder to grind punches and dies of any curved shape. Cavity molds are mostly processed by profiling milling machines, electrical discharge machining and electrolytic machining. The combined application of copy milling and numerical control and the addition of a three-way translation head device in EDM can improve the machining quality of the cavity. The addition of gas-filled electrolysis in electrolytic processing can improve production efficiency.

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  • 2022.04.01

    Do you know the template design of the mold?

    Do you know the template design of the mold? The main templates of continuous molds include punch fixing plate, pressing plate, concave plate, etc. The structural design depends on the accuracy of stamping products, production quantity, processing equipment and processing methods of the mold, and maintenance methods of the mold, etc. There are the following three types Forms: (1) Monolithic, (2) Yoke, (3) Inserted. 1. Monolithic Monolithic formwork is also known as one-piece construction type, and its processing shape must be closed. The monolithic template is mainly used for the mold with simple structure or low precision. Its processing method is mainly cutting (without heat treatment). The template with heat treatment must be subjected to wire cutting or electrical discharge machining and grinding. When the size of the template is long (continuous mold), two or more pieces of one-piece type will be used together. 2. yoke The central part of the yoke formwork is grooved to assemble block products. Its structure is based on application requirements, and the groove portion can be formed by other templates. The advantages of this yoke formwork structure are: the groove part is easy to process, the groove part width can be adjusted, and the processing accuracy is good. But low rigidity is its disadvantage. The design considerations for the yoke formwork are as follows: (1) The fitting of the yoke plate structure and the block parts adopts the middle or light fitting method. If the strong press fit is adopted, the yoke plate will change. (2) The yoke plate also has the function of retaining the block parts, and must have sufficient rigidity to withstand the side pressure and surface pressure of the block parts. In addition, in order to make the grooves of the yoke plate and the block parts closely combined, the corners of the grooves are processed for clearance. If the corners of the grooves of the yoke plate cannot be processed for clearance, the block parts must be processed for clearance. (3) The division of block parts should also consider the internal shape, and the reference plane must be clarified. In order to prevent deformation during stamping, attention should also be paid to the shape of each block-shaped part. (4) When many pieces of block parts are assembled into the yoke plate, the pitch changes due to the accumulated error of the processing of each block part. The solution is to design the middle block parts in an adjustable way. (5) The block parts adopt the mold structure of side-by-side combination, because the block parts will be subjected to lateral pressure during punching processing, which will cause gaps between the block parts or cause the block parts to tilt. This phenomenon is an important cause of poor punching such as poor punching dimensions and clogging of punching chips, so adequate countermeasures are required. (6) The fixing methods of the block parts in the yoke plate are as follows according to their size and shape: A. Fix with locking screws, B. Fix with keys, C. Fix with swivel keys, D. With shoulders Fix, E. The above pressing parts (such as guide plates) are pressed and fixed. 3. Built-in The circular or square concave parts are processed in the template, and the block parts are embedded in the template. This template is called an embedded structure. This structure has less cumulative machining tolerance, high rigidity, and accurate reproducibility during disassembly and assembly. good. Due to the advantages of easy machining, the machining accuracy is determined by the working machine, and the final adjustment process is less, the insert-type template structure has become the mainstream of precision stamping dies, but its disadvantage is that a high-precision hole processing machine is required. When the continuous stamping die adopts this template structure, in order to make the template have high rigidity requirements, an empty station is designed. Precautions for the construction of a built-in template are as follows: (1) Processing of embedded holes: vertical milling machines (or jig milling machines), comprehensive processing machines, jig boring machines, jig grinders, wire-cut electrical discharge machines, etc. are used for the processing of embedded holes in the template. The machining standard for embedding holes, when using a wire-cut electric discharge machine, in order to improve its machining accuracy, two or more wire-cutting processes are performed. (2) Fixing method of inserts: The determinants of the fixing method of inserts include the accuracy of processing, the ease of assembly and disassembly, and the possibility of adjustment. There are four ways to fix the insert: A. Fix it with screws, B. Fix it with the shoulder, C. Fix it with the toe block, D. The upper part is pressed with a plate. The insert fixing method of the concave formwork also adopts press fit. At this time, the relaxation result caused by the thermal expansion of processing should be avoided. When using the circular die insert to process irregular holes, a rotation prevention method should be designed. (3) Considerations for the assembly and disassembly of the inserts: The machining accuracy of the inserts and their holes is required to be high for assembly operations. In order to obtain even a slight dimensional error that can be adjusted at the time of assembly, it is advisable to consider solutions in advance. The specific considerations for the processing of inserts are as follows: A. There is a press-in introduction part, B. The spacer is used to adjust the insert The pressed state and correct position of the parts, C. There are holes for pressing out on the bottom surface of the inserts. D. Screws of the same size should be used when locking with screws to facilitate locking and loosening. E. In order to prevent the assembly direction from changing If mistakes are made, fool-proof chamfering should be designed.

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  • 2022.03.22

    Design principle of mold

    Design principle of mold Because different forming molds have been applied in many fields, and the manufacturing technology of professional molds has also changed and developed in recent years, in this part, the general design rules of vacuum forming molds are summarized. The design of vacuum forming mold includes batch size, molding equipment, precision conditions, geometric shape design, dimensional stability and surface quality. 1. The batch size is used for experiments, the mold output is small, and wood or resin can be used for manufacturing. However, if the experimental mold is to obtain data about shrinkage, dimensional stability and cycle time of the product, a single cavity mold should be used for the experiment, and it can be guaranteed to be used under production conditions. Molds are generally made of plaster, copper, aluminum or aluminum-steel alloys, and aluminum-resin is rarely used. 2. Geometric shape design. When designing, dimensional stability and surface quality are often considered comprehensively. For example, product design and dimensional stability require the use of female molds (concave molds), but products that require high gloss on the surface require the use of male molds (punch molds). point so that the product can be produced under optimal conditions. Experience has shown that designs that do not meet actual machining conditions often fail. 3. Dimensional stability. During the molding process, the surface of the plastic part in contact with the mold has better dimensional stability than the part that leaves the mold. If the material thickness needs to be changed in the future due to the material stiffness, it may lead to the conversion of the male mold to the female mold. The dimensional tolerance of plastic parts cannot be less than 10% of the shrinkage.4. As far as the surface of the plastic part can be covered by the molding material, the surface structure of the visible surface of the plastic part should be formed at the contact point with the mold. If possible, the smooth surface of the plastic part should not come into contact with the mold surface. As is the case with the use of female molds for bathtubs and laundry tubs. 5. For decoration, if a mechanical horizontal saw is used to saw off the clamping edge of the plastic part, there should be at least a 6-8mm margin in the height direction. Other finishing work, such as grinding, laser cutting or jetting, must also be left over. The gap between the cutting lines of the knife edge die is the smallest, and the distribution width of the punching die during trimming is also small, which should be paid attention to. 6. Shrinkage and deformation, plastic is easy to shrink (such as PE), and some plastic parts are easy to deform. No matter how to prevent it, plastic parts will deform during the cooling stage. Under this condition, it is necessary to change the shape of the forming mold to adapt to the geometric deviation of the plastic part. For example: although the wall of the plastic part remains straight, its reference center has been deviated by 10mm; the mold base can be raised to adjust the amount of shrinkage of this deformation. 7. Shrinkage: The following shrinkage factors must be taken into account when manufacturing blister forming molds. ① Shrinkage of molded products. If the shrinkage rate of the plastic cannot be clearly known, it must be obtained by sampling or testing with a similarly shaped mold. Note: Only the shrinkage rate can be obtained by this method, and the deformation size cannot be obtained. ② Shrinkage caused by the adverse effects of intermediate media, such as ceramics, silicone rubber, etc. ③ Shrinkage of the material used in the mold, such as shrinkage when casting aluminum.

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  • 2022.03.14

    Seven matters should be paid attention to in the development and injection of medical device molds

    Seven matters should be paid attention to in the development and injection of medical device moldsCompared with ordinary molds, the control in the manufacturing process of medical device accessories molds is different. We need to pay attention to the following matters. 1, We need to know whether the customer's product belongs to class 1, class 2 or class 3 medical devices. In the process of making medical device molds, the automation, cleanliness and production process control are different. For example, if it is class 2 medical consumables, we design the mold In the process, fully automated production will be considered to reduce the participation of personnel, and the ejection and lubrication systems will be different from ordinary molds, reducing the pollution of oil contamination to medical equipment products. 2, We will also recommend suitable medical plastics according to the specific needs of customers' medical products. Engaged in medical injection molding for more than 10 years, we have accumulated rich information on medical plastics at home and abroad, which can help customers choose medical equipment and medical equipment suitable for you. Suitable plastic for consumables. Not only from the use of medical products, but also from the medical injection molding process to help customers reduce costs and improve quality. We firmly believe that easy processing and smooth process are the key factors to ensure the quality and low price of medical plastic products. 3. The barrel temperature of ordinary injection molding machines cannot meet the melting requirements of high-temperature plastics. For the injection of high-temperature medical plastic products, the company is also equipped with specific medical injection molding machines to produce high-temperature medical plastic products. 4, The company is equipped with imported medical micro-injection molding machines, which are specialized in the injection molding production of small products ranging from 0.1g to 0.5g to ensure product accuracy. 5, We will choose the appropriate mold structure and injection molding production plan according to your medical plastic production and processing quantity requirements, product structure and quality requirements, and will also help you recommend suitable and cost-effective medical plastics. 6, Before the medical device mold is opened, we will provide a manufacturable information report to ensure that you and us have a consistent understanding of quality, structure and product optimization, while eliminating the risk of mold development and medical plastic production. 7, At the beginning of your inquiry, we will ask you about the requirements of medical packaging methods, to ensure the cost and medical product packaging safety in the early stage

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  • 2022.03.07

    The principle of mold design

    The principle of mold design Because different forming molds have been applied in many fields, and the manufacturing technology of professional molds has also changed and developed in recent years, in this part, the general design rules of vacuum forming molds are summarized. The design of vacuum forming mold includes batch size, molding equipment, precision conditions, geometric shape design, dimensional stability and surface quality. 1. The batch size is used for experiments, the mold output is small, and wood or resin can be used for manufacturing. However, if the experimental mold is to obtain data about shrinkage, dimensional stability and cycle time of the product, a single cavity mold should be used for the experiment, and it can be guaranteed to be used under production conditions. Molds are generally made of plaster, copper, aluminum or aluminum-steel alloys, and aluminum-resin is rarely used. 2. Geometric shape design. When designing, dimensional stability and surface quality are often considered comprehensively. For example, product design and dimensional stability require the use of female molds (concave molds), but products that require high gloss on the surface require the use of male molds (punch molds). point so that the product can be produced under optimal conditions. Experience has shown that designs that do not meet actual machining conditions often fail. 3. Dimensional stability. During the molding process, the surface of the plastic part in contact with the mold has better dimensional stability than the part that leaves the mold. If the material thickness needs to be changed in the future due to the material stiffness, it may lead to the conversion of the male mold to the female mold. The dimensional tolerance of plastic parts cannot be less than 10% of the shrinkage. 4. As far as the surface of the plastic part can be covered by the molding material, the surface structure of the visible surface of the plastic part should be formed at the contact point with the mold. If possible, the smooth surface of the plastic part should not come into contact with the mold surface. As is the case with the use of female molds for bathtubs and laundry tubs. 5. For decoration, if a mechanical horizontal saw is used to saw off the clamping edge of the plastic part, there should be at least a 6-8mm margin in the height direction. Other finishing work, such as grinding, laser cutting or jetting, must also be left over. The gap between the cutting lines of the knife edge die is the smallest, and the distribution width of the punching die during trimming is also small, which should be paid attention to. 6. Shrinkage and deformation, plastic is easy to shrink (such as PE), and some plastic parts are easy to deform. No matter how to prevent it, plastic parts will deform during the cooling stage. Under this condition, it is necessary to change the shape of the forming mold to adapt to the geometric deviation of the plastic part. For example: although the wall of the plastic part remains straight, its reference center has been deviated by 10mm; the mold base can be raised to adjust the amount of shrinkage of this deformation. 7. Shrinkage: The following shrinkage factors must be taken into account when manufacturing blister forming molds. ① Shrinkage of molded products. If the shrinkage rate of the plastic cannot be clearly known, it must be obtained by sampling or testing with a similarly shaped mold. Note: Only the shrinkage rate can be obtained by this method, and the deformation size cannot be obtained. ② Shrinkage caused by the adverse effects of intermediate media, such as ceramics, silicone rubber, etc. ③ Shrinkage of the material used in the mold, such as shrinkage when casting aluminum.

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  • 2022.03.02

    How is the mold made?

    How is the mold made? Production Process A mold is a model, and products are made according to this model, but how the mold is produced may not be answered by most professionals except for the mold. The mold has played an irreplaceable role in our life. Our daily necessities Most of them are inseparable from molds, such as computers, telephones, fax machines, keyboards, cups, etc. These plastic products need not be mentioned. In addition, the covers of automobiles and motorcycle engines are also made of molds. More than 20,000 molds are used for various molds. Therefore, the role of molds in modern life is irreplaceable. As long as mass production is inseparable from molds. So how is the mold made? The following is a brief introduction to the modern mold production process. 1) ESI: This stage is mainly a technical discussion between customers and suppliers on product design and mold development. The main purpose is to allow suppliers to clearly understand the design intent and accuracy requirements of product designers. At the same time, it also allows product designers to better understand the ability of mold production and the process performance of products, so as to make more reasonable designs. 2) Quotation: including the price of the mold, the life of the mold, the turnover process, the required tonnage of the machine and the delivery time of the mold. (A more detailed quotation should include product size weight, mold size weight and other information.) 3) Order (Purchase Order): customer orders, the issuance of deposits and the acceptance of supplier orders. 4) Mold Production Planning and Schedule Arrangement: At this stage, it is necessary to reply to the customer for the specific date of mold delivery. 5) Mold Design: Design software that may be used include Pro/Engineer, UG, Solidworks, AutoCAD, CATIA, etc. 6) Procurement of materials 7) Mould processing (Machining): The processes involved generally include turning, gong (milling), heat treatment, grinding, computer gong (CNC), electric spark (EDM), wire cutting (WEDM), coordinate grinding (JIG GRINGING), Laser engraving, polishing, etc. 8) Mold assembly (Assembly) 9) Trial Run 10) Sample Evaluation Report (SER) 11) Model evaluation report approval (SER Approval)

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  • 2022.02.21

    Inspection during mold making

    Inspection during mold making The control of the raw materials of the mold is carried out from the following aspects: 1. Macro inspection The chemical composition is decisive to ensure the performance of the steel, but the composition is qualified and cannot fully explain the performance of the steel. Due to the inhomogeneity of the internal structure and composition of the steel, the macro inspection supplements this deficiency to a large extent. Macroscopic inspection can observe the crystallization of the steel, the failure of the continuity of the steel and the inhomogeneity of some components. There are 8 common macro defects: segregation, porosity, inclusions, shrinkage cavities, bubbles, white spots, cracks, and folds. 2. Evaluation of annealing structure The purpose of annealing is to reduce the hardness of the steel, facilitate machining, and also prepare the structure for subsequent heat treatment. The annealed structure of carbon tool steel is evaluated according to the first-level rating chart of GB1298. 3. Carbide inhomogeneity Cr12 type ledeburite steel contains a large amount of eutectic carbides in the structure, and the inhomogeneity of carbides has a very important influence on the performance, so the distribution of its carbides must be strictly controlled. All in all, due to the cumbersome production objects of mold factories and workshops, and more or less single pieces and small batches, it brings certain difficulties to the formulation and management of mold production quotas. In addition, the production methods of each factory and workshop, The equipment and technical quality are not the same, so when setting the quota, it is necessary to find an appropriate method to formulate an advanced and reasonable working hour quota according to the actual situation of the factory and workshop, in order to improve labor productivity.

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  • 2022.02.16

    What are the key points of mold design

    What are the key points of mold design Work steps 1. Review items before design 1. Mold material 2. Molded product 3. Molding machine selection 4. Basic structure of die base 2. Important items of mold design (1). Multi-color injection combination 2. runner system (1) The injection pressure is low. (2) Fast filling is completed, which can increase the output. (3) It can be uniformly injected, and the product quality is better. (4) Reduce waste and shorten injection time. 3. Forming equipment: (1) The injection volume of each injection cylinder determines which material cylinder is used for which color. (2) The position and stroke of the striker. (3) The configuration of the water circuit, oil circuit, and circuit on the rotating disk. (4) The bearing weight of the rotating disc. 4. Mold base design: mold core configuration design First of all, considering that the male mold side of the mold must be rotated 180 degrees, the mold core settings must be arranged in a cross-symmetrical arrangement, otherwise the mold cannot be closed and formed. (1) Guide post: It has the function of guiding the male mold and the female mold. Concentricity must be maintained in the multi-color mold. (2) Return pin: Since the mold must rotate, the ejector plate must be fixed, and a spring is added to the return pin to keep the ejector plate stable. (3) Positioning block: ensure that the two mold bases are not offset due to the gap of the screws when they are fixed on the large solid plate. (4) Adjustment block (wear-resistant block): It is mainly used to adjust the z coordinate value of the mold height when the mold is closed. (5) Ejection mechanism: The design of the ejection method is the same as that of the general mold. (6) Design of cooling circuit: The cooling circuit design of mold one and mold two should be the same as possible.

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  • 2022.02.12

    Other classifications of molds

    Other classifications of molds (1) Hot runner mold With the help of the heating device, the plastic in the gating system will not solidify, nor will it be demolded with the product, so it is also called a runnerless mold. Advantages: 1) No waste 2) Can reduce injection pressure, can use multi-cavity mold 3) Can shorten molding cycle 4) Improve product quality Features suitable for hot runner molding compounds: 5) The melting temperature range of plastics is wide. At low temperature, it has good fluidity, and at high temperature, it has better thermal stability. 6) Sensitive to pressure, does not flow without pressure, but can flow when pressure is applied. 7) Good specific heat, so that it can be cooled quickly in the mold. Available hot runner plastics are PE, ABS, POM, PC, HIPS, PS. There are two commonly used hot runners: 1) heating runner molds 2) adiabatic runner molds. (2) Hard mold The steel plate used in the inner mold needs to be heat treated after buying it, such as quenching and carburizing, to meet the requirements of use. Such an injection mold is called a hard mold. For example, the inner mold is made of H13 steel, 420 steel, and S7 steel. (3) Soft mold (below 44HRC) The steel used in the inner mold can meet the requirements of use without heat treatment after purchase. Such injection molding is called soft mold. For example, the inner module adopts P20 steel, ace steel, 420 steel, NAK80, aluminum, beryllium copper. Suzhou Huihong Electric Co., Ltd. is a professional manufacturer of precision molds , injection molding, assembling and silk-printing. Some moulds are exported to Japan, Europe and the United States. We have the right to import and export the goods. We can develop and manufacture the moulds according to the needs of our customers. We pay attention to quality control, new project development, personnel training, team spirit. In recent years, we have established long-term business relationships with many well-known enterprises at home and abroad.

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  • 2022.02.09

    Two,Die casting classification

    (4) Injection molding Also known as die casting. It is to add plastic raw materials into the preheated feeding chamber, then put the pressure column into the charging chamber to lock the mold, and apply pressure to the plastic through the pressure column. The plastic melts into a flowing state under high temperature and high pressure, and enters the cavity through the pouring system. It gradually solidifies into a plastic part. This molding method is also called transfer molding. Injection molding is suitable for plastics that are lower than solid plastics and can be compression molded in principle, and can also be molded by injection molding. However, it is required that the molding material has good fluidity in the molten state when it is lower than the curing temperature, and has a larger curing rate when it is higher than the curing temperature. (5) Blow molding It is to fix the tubular or sheet-like blanks in the plasticized state made by extrusion or injection into the molding die, and immediately introduce compressed air to force the blanks to expand and stick to the wall of the mold cavity. A processing method for obtaining the desired hollow product by demoulding after cooling and shaping. Plastics suitable for hollow molding are high pressure polyethylene, low pressure polyethylene, hard polyvinyl chloride, soft polyvinyl chloride, polystyrene, polypropylene, polycarbonate, etc. According to different parison molding methods, hollow molding is mainly divided into extrusion blow molding and injection blow molding. The advantage of extrusion blow molding is that the structure of the extruder and the extrusion blow mold is simple, and the disadvantage is that the wall thickness of the parison is inconsistent, which is easy to cause uneven wall thickness of plastic products. The advantage of injection blow molding hollow molding is that the wall thickness of the parison is uniform and there is no flash. Since the injection parison has a bottom surface, the bottom of the hollow product will not have joints and seams, which is not only beautiful but also high in strength. The disadvantage is that the molding equipment and molds used are expensive, so this molding method is mostly used in the mass production of small hollow products, and it is not widely used in extrusion blow molding. (6) Die-casting mold Die casting molds are also called transfer molding molds. The plastic raw material is added to the preheated feeding chamber, and then pressure is applied to the pressure column. The plastic is melted under high temperature and high pressure, and enters the cavity through the casting system of the mold, and gradually hardens and forms. This molding method is called die casting. The mold used It is called die casting mould. This kind of mold is mostly used for the molding of thermosetting plastics.

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  • 2022.01.26

    Mold casting classification

    Mold casting classification(1) Injection moldingThe plastic is first added to the heating barrel of the injection machine, and the plastic is heated and melted. Under the push of the screw or plunger of the injection machine, it enters the mold cavity through the nozzle and the mold pouring system, and is hardened and shaped into injection molding due to physical and chemical effects. product. Injection molding consists of a cycle consisting of injection, pressure holding (cooling) and plastic part demolding processes, so injection molding has the characteristics of periodicity. Thermoplastic injection molding has a short molding cycle, high production efficiency, and low wear on the mold by the melt. It can mold plastic parts with complex shapes, clear surface patterns and markings, and high dimensional accuracy in large quantities; however, for plastics with large wall thickness changes. It is difficult to avoid molding defects. Anisotropy of plastic parts is also one of the quality problems, and all possible measures should be taken to minimize it.(2) Compression moldingCommonly known as compression molding, it is one of the earliest methods of molding plastic parts. Compression molding is to directly add plastic into an open mold cavity with a certain temperature, then close the mold, and melt the plastic into a flowing state under the action of heat and pressure. Due to physical and chemical effects, the plastic is hardened into a plastic part with a certain shape and size that remains unchanged at room temperature. Compression molding is mainly used for molding thermosetting plastics, such as phenolic molding powder, urea-formaldehyde and melamine-formaldehyde molding powder, glass fiber reinforced phenolic plastic, epoxy resin, DAP resin, silicone resin, polyimide and other molding compounds, It can also be processed into unsaturated polyester dough (DMC), sheet molding compound (SMC), prefabricated integral molding compound (BMC), etc. Under normal circumstances, compression dies are often divided into three types: overflow type, non-overflow type, and semi-overflow type according to the matching structure of the upper and lower molds of the compression film.(3) Extrusion moldingIt is a molding method in which the plastic in a viscous flow state passes through a die with a specific cross-sectional shape at a high temperature and a certain pressure, and then is shaped into a continuous profile with the desired cross-sectional shape at a lower temperature. The production process of extrusion molding is preparation of molding materials, extrusion molding, cooling and shaping, traction and cutting, and post-processing (quenching and tempering or heat treatment) of extruded products. In the extrusion molding process, pay attention to adjusting the temperature, screw revolutions, traction speed and other process parameters of each heating section of the extruder barrel and the die in order to obtain qualified extrusion profiles. Special attention should be paid to adjusting the rate at which the polymer melt is extruded from the die. Because when the extrusion rate of the molten material is low, the extrudate has a smooth surface and a uniform cross-sectional shape; but when the extrusion rate of the molten material reaches a certain limit, the surface of the extrudate will become rough and tarnished , appear shark skin, orange peel, shape distortion and other phenomena. When the extrusion rate was further increased, the extrudate surface was distorted and even fragmented and fractured into melt fragments or cylinders. Therefore, the control of extrusion rate is very important.

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