Question 1: What are the plastic mold materials? The most important factors of mold materials are thermal strength and thermal stability. Commonly used mold materials: working temperature forming materials mold materials
1000℃ Nickel alloy copper-based alloy molds, carbide molds.
Question 2: What are the classifications of plastic molds? According to the different molding methods, plastic processing mold types corresponding to different process requirements can be divided, mainly including injection molding molds, extrusion molding molds, blister molding molds, high-expanded polystyrene molding molds, etc.
1. Plastic injection (plastic) mold
It is mainly the most commonly used molding mold in the production of thermoplastic plastic parts. The corresponding processing equipment for plastic injection molds is plastic injection molds. In the molding machine, the plastic is first heated and melted in the heating barrel at the bottom of the injection machine. Then, driven by the screw or plunger of the injection machine, it enters the mold cavity through the nozzle of the injection machine and the pouring system of the mold. The plastic is cooled and hardened to form, and demolded to obtain products. Its structure usually consists of molding parts, pouring system, guide parts, push-out mechanism, temperature adjustment system, exhaust system, support parts and other parts. Manufacturing materials usually use plastic mold steel modules. Commonly used materials are mainly carbon structural steel, carbon tool steel, alloy tool steel, high-speed steel, etc. Injection molding processing method is usually only suitable for the production of thermoplastic products. Plastic products produced by injection molding process are very wide, ranging from daily necessities to various complex machinery, electrical appliances, transportation parts, etc., are all molded with injection molds. It is the most widely used processing method in the production of plastic products.
2. Plastic compression mold
Includes two structural mold types: compression molding and injection molding. They are a type of mold mainly used to shape thermosetting plastics, and their corresponding equipment is a pressure forming machine. The compression molding method heats the mold to the molding temperature (usually 103°-108°) according to the characteristics of the plastic, then puts the measured compression molding powder into the mold cavity and feeding chamber, closes the mold, and the plastic is heated under the action of high heat and high pressure. It appears as a softened viscous flow, and after a certain period of time, it solidifies and becomes the desired product shape. The difference between injection molding and compression molding is that there is a separate feeding chamber. The mold is closed before molding. The plastic is preheated in the feeding chamber and becomes a viscous flow state. It is adjusted and extruded into the mold cavity under pressure and hardened to form. Compression molds are also used to form certain special thermoplastics such as difficult-to-melt thermoplastics (such as polyethylene fluoride) blanks (cold press molding), resin lenses with high optical properties, slightly foamed nitrocellulose car steering wheels, etc. . The compression mold is mainly composed of a cavity, a feeding cavity, a guide mechanism, an ejection component, a heating system, etc. Injection molds are widely used in packaging electrical components. The materials used in the manufacture of compression molds are basically the same as those used in injection molds.
3. Plastic extrusion mold
A type of mold used to shape and produce continuous-shaped plastic products. It is also called an extrusion molding head. It is widely used in pipes, rods, Processing of monofilaments, sheets, films, wire and cable coatings, special-shaped materials, etc. The corresponding production equipment is a plastic extruder. The principle is that the solid plastic is melted and plasticized under the conditions of heating and screw rotation and pressure of the extruder, and then passed through a die of a specific shape to make a cross-section with the same shape as the die. Continuous plastic products. Its manufacturing materials mainly include carbon structural steel, alloy tools, etc. Some extrusion molds are also inlaid with diamond and other wear-resistant materials on the parts that need to be wear-resistant. The extrusion process is usually only suitable for the production of thermoplastic plastic products, and its structure is significantly different from injection molds and compression molds.
4. Plastic blow molding mold
It is a mold used to form hollow plastic container products (such as beverage bottles, daily chemical products and other packaging containers). Blow molding According to the process principle, the molding forms mainly include extrusion blow molding, injection blow molding, injection stretch blow molding (commonly known as "injection stretch blow molding"), multi-layer blow molding, sheet blow molding, etc. . The equipment corresponding to the blow molding of hollow products is usually called a plastic blow molding machine. Blow molding is only suitable for the production of thermoplastic products.
The structure of the blow mold is relatively simple, and the materials used are mostly made of carbon.
5. Plastic blister mold
It is a mold that uses plastic plates and sheets as raw materials to form some simple plastic products. The principle is to use the vacuum opening method or The compressed air molding method causes the plastic plates and sheets fixed on the concave or convex mold to deform under the condition of heating and softening and stick to the cavity of the mold to obtain the required molded products. It is mainly used for some daily necessities, food, and toys. Packaging product production. Due to the low pressure during molding, the blister mold is mostly made of cast aluminum or non-metallic materials, and the structure is relatively simple.
6. High-expanded polystyrene molding mold
It uses expandable polystyrene (bead-shaped material composed of polystyrene and foaming agent) raw material to shape various products. A mold for foam plastic packaging materials of a desired shape. The principle is that expandable polystyrene can be molded with steam in the mold, including simple manual operation molds and hydraulic press straight-through foam plastic molds, which are mainly used...gt;gt;
Question 3: Material selection for plastic molds 1. Working conditions of plastic molds Due to the development of the plastics and plastic molding industries, the quality requirements for plastic molds are getting higher and higher. Therefore, the failure problem of plastic molds and its influencing factors have become become an important research topic. The main working parts of plastic molds are molding parts, such as punches, concave molds, etc., which form the cavity of the plastic mold to shape various surfaces of plastic parts and are in direct contact with plastics to withstand pressure, temperature, friction and corrosion, etc. effect. 2. Analysis of causes of failure of plastic mold materials. General mold manufacturing includes processes such as mold design, material selection, heat treatment, machining, debugging and installation. According to the survey, among the factors that cause mold failure, the materials and heat treatment used in the mold are the main factors that affect the service life. From the perspective of total quality management, the factors that affect the service life of the mold cannot be measured as the sum of polynomials, but should be the product of multiple factors. In this way, the quality of mold materials and heat treatment is particularly important in the entire mold manufacturing process. important. From the analysis of the common phenomenon of mold failure, plastic molds can cause wear failure, local deformation failure and fracture failure during service. The important failure modes of plastic molds can be divided into wear failure, local plastic deformation failure and fracture failure. 3. Performance requirements of plastic mold steel With the rapid development of the manufacturing industry, plastic molds are indispensable tools in plastic molding processing, and their proportion in the total mold output is increasing year by year. With the development and continuous production of high-performance plastics, The types of plastic products are increasing day by day, their uses are expanding, and the products are becoming more sophisticated, large-scale, and complex. Molding production is developing towards high speed, and the working conditions of molds are becoming more and more complex. 1) Wear and corrosion on the surface of the mold cavity. The plastic melt flows in the mold cavity under a certain pressure, and the solidified plastic parts come out of the mold, which causes friction on the molding surface and causes wear. The fundamental cause of plastic mold wear and failure is the friction between the mold and the material. However, the specific form and wear process of wear are related to many factors, such as the pressure, temperature, material deformation speed and lubrication conditions of the mold during the working process. When the materials and heat treatment used in the plastic mold are unreasonable, the surface hardness of the cavity of the plastic mold is low and the wear resistance is poor, which is manifested as: the size of the cavity surface is out of tolerance due to wear and deformation; the roughness value becomes higher due to roughening , the surface quality deteriorates. Especially when solid materials are used to enter the mold cavity, it will increase the wear of the cavity surface. In addition, during plastic processing, components such as chlorine and fluorine are heated and decompose to produce corrosive gases HC1 and HF, which cause corrosion and wear on the cavity surface of the plastic mold, leading to failure. If there is wear damage at the same time as the wear, the coating or other protective layer on the surface of the cavity is destroyed, which will promote the corrosion process. The cross-effect of the two types of damage accelerates corrosion-wear failure. 2) Plastic deformation failure: Pressure and heat on the surface of the plastic model cavity can cause plastic deformation failure. Especially when small molds are working on large-tonnage equipment, overload plastic deformation is more likely to occur.
The material used in the plastic mold has insufficient strength and toughness, and low deformation resistance; another reason for plastic deformation failure is that the hardened layer on the surface of the mold cavity is too thin, the deformation resistance is insufficient, or the working temperature is higher than the tempering temperature, resulting in phase change softening. , causing the mold to fail early. 3) The main reason for fracture is structural stress, thermal stress due to structure and temperature difference, or insufficient tempering, which transforms retained austenite into martensite at the operating temperature, causing local volume expansion inside the mold. Caused by tissue stress. The working conditions of plastic molds are different from those of cold stamping dies. They generally have to work at 150℃-200℃. In addition to being subject to a certain pressure, they also have to withstand the influence of temperature. The same mold will have multiple failure modes, and multiple types of damage may occur even on the same mold. It can be seen from the failure modes of plastic molds that the reasonable selection of plastic mold materials and heat treatment is very important, because they are directly related to the service life of the mold. Therefore, steel for plastic molds should meet the following requirements: 1) Heat resistance With the emergence of high-speed molding machinery, plastic products run faster. Since the molding temperature is between 200--350℃, if the plastic fluidity is poor and the molding speed is fast, the molding surface temperature of the mold part will exceed 400℃ in a very short time. In order to ensure the accuracy and minimal deformation of the mold during use, the mold steel should have high heat resistance. 2) Sufficient wear resistance With the expansion of the use of plastic products, inorganic materials such as glass fiber are often added to plastics to enhance plasticity. Due to the addition of additives, the fluidity of the plastic is greatly reduced, resulting in wear of the mold. , so the chess piece is required to have good wear resistance. 3) Excellent...gt;gt;
Question 4: What are the commonly used injection molding materials: PE PP PS ABS PC PA POM PBT PMMA, etc.
Question 5: What material is better to use to make molds? 3Cr2NiMo (P4410) plastic mold steel
P4410 steel has a hardness value in the range of 32 to 36HRC and has good processing properties such as turning, milling, and grinding.
P4410 steel can also be locally heated and quenched by flame. The heating temperature is 800~825℃, and it is cooled in the air or with compressed air. The local surface hardness can reach 56~62HRC, which can extend the service life of the mold. The surface of the mold can also be chromium plated, and the surface hardness can be increased from 370 to 420HV to 1000HV, which can significantly improve the wear resistance and corrosion resistance of the mold.
Molds made of P4410 steel can also be repaired by repair welding after partial damage. The welding quality is good and can be processed.
P4410 steel is used in a pre-hardened state (30~36HRC), which prevents heat treatment deformation and is suitable for manufacturing large, complex, and precision plastic molds. This steel can also be treated with chemical heat treatments such as nitriding and boronization. After treatment, higher surface hardness can be obtained, making it suitable for making high-precision plastic molds.
8Cr2MnWMoVS (8Cr2S) steel
8Cr2MnWMoVS is an easy-cutting precision plastic forming mold steel. It is designed to meet the urgent needs of precision plastic molds and thin plate gap-free precision blanking dies. The composition design adopts the principle of high carbon multi-element small amount alloying, using sulfur as an easy-cutting element. The chemical composition and properties of 8Cr2S steel have been introduced in the second section of Chapter 1, and the use will be further introduced here.
1. Characteristics of steel
(1) The heat treatment process is simple and the hardenability is good: the air-cooling quenching diameter is more than φ100mm, the air-quenching hardness is 61.5~62HRC, and the heat treatment deformation is small. When quenched at 860~900℃ and tempered at 160~300℃, the total axial deformation rate is <0.09 and the total radial deformation rate is <0.15.
(2) Good cutting performance: the annealing hardness is 207~239HBS. During cutting, the processing time can be shortened by more than 1/3 compared with ordinary tool steel.
When the hard state is 40~45HRC, using high-speed steel or carbide tools for turning, milling, planing, boring, drilling and other processing is equivalent to the cutting performance of carbon steel in the quenched and tempered state, with a hardness of about 30HRC, which is far better than annealed Cr12MoV steel. Cutting performance when hardness is 240HBS.
(3) Mirror grinding and polishing properties are good: using the same grinding process, its surface roughness is 1 to 2 levels lower than that of general alloy tool steel, and the minimum surface roughness is Ra 0.1μm.
(4) Good surface treatment performance: good nitriding performance, generally the depth of the nitriding layer is 0.2~0.3mm, and the boronization adhesion is strong.
2. Application
As pre-hardened steel, 8Cr2S is suitable for making various types of plastic molds, bakelite molds, ceramic molds and punching molds for printed boards. The mold fitting precision made by this steel type is 1 to 2 orders of magnitude higher than that of other alloy tool steels, the surface roughness is 1 to 2 levels lower, and the service life is generally 2 to 3 times higher, and some are more than ten times higher.
5CrNiMnMoVSCa (5NiSCa) steel
5NiSCa is an easy-cutting and high-toughness plastic mold steel. In the pre-hardened state (35~45HRC), it has good toughness and machinability; it has good mirror polishing performance. The surface roughness is low, reaching Ra 0.2~0.1μm, and the surface roughness can be maintained well during use; the pattern etching performance is good, clear and realistic; the hardenability is good, and it can be used for plastic molds with complex cavities and high quality requirements. Under high hardness (above 50HRC), this steel has small heat treatment deformation, good toughness, and has good ability to prevent crack expansion.
1. Chemical composition and phase transformation point
5NiSCa steel is made of medium carbon plus nickel. Its main chemical composition is shown in Table 3-9.
Table 3-9 Chemical composition of 5NiSCa steel (mass fraction) ()
C Cr Ni Mn Mo V S Ca
0.57 0.89 1.03 1.19 0.52 0.26 0.028 0.0036
The phase change point is 695~735℃ when heated, 378~305℃ when cooled, Ms220℃.
2. Process performance
(1) Forging: heating temperature 1100℃, initial forging temperature 1070~1100℃, final forging temperature 850℃, sand cooling after forging.
(2) Spheroidizing annealing: heating temperature 770℃, holding for 3h, isothermal temperature 660℃, holding for 7h, cooling the furnace to 550℃ and air cooling. Annealing hardness ≤241HBS, good processing performance.
(3) Quenching: Quenching temperature 8...gt;gt;
Question 6: What are the commonly used materials for molds? Plastic mold steel: 45#, P20, 4Cr13 ...
Cold work die steel: Cr12, Cr12MoV, D2....
Hot work die steel: H13, 5CrMnMo, 3Cr2W8V....
Huangshi Dongxin Special Steel Co., Ltd. specializes in the production of tool and die steel. Centennial Daye Special Steel Technology.
Question 7: What are the basis for selecting plastic mold materials? Strength, hardness, heat treatment performance, product quantity, corrosion resistance, etc.
Question 8: How many types of molds are there? Molds can be divided into metal molds and non-metal molds. Metal molds are further divided into: casting molds (non-ferrous metal die-casting, steel casting), and forging molds, etc.; non-metal molds are also divided into: plastic molds and inorganic non-metal molds. According to the different materials of the mold itself, the mold can be divided into: sand mold, metal mold, vacuum mold, paraffin mold, etc. Among them, with the rapid development of polymer plastics, plastic molds are closely related to people's lives. Plastic molds can generally be divided into: injection molding molds, extrusion molding molds, gas-assisted molding molds, etc. Mass production of non-sheet metal steel parts - cold heading, die forging, metal molds, etc.
Mold sheet metal discharging - hot rolling, cold rolling, hot coiling, cold coiling sheet metal processing - deep drawing, shaping, bending, punching, blanking non-ferrous metals - die casting, powder metallurgy plastic parts - injection molding , blow molding (plastic bottles), extrusion (pipe fittings) molds Other categories: alloy molds, sheet metal molds, plastic molds, stamping molds, casting molds, forging molds, extrusion molds, die-casting molds, automobile molds, thread rolling molds
Question 9: What are the commonly used materials for molds and how much does it cost? 618 pre-hardened plastic mold steel
28 yuan/Kg
718 pre-hardened plastic mold steel
40 yuan/Kg
718H pre-hardened plastic mold steel
44 yuan/Kg
S136 high-quality corrosion-resistant mirror mold steel
80 yuan/Kg
S136H high-quality corrosion-resistant mirror mold steel
85 yuan/Kg
8402 hot die-casting mold steel
64 yuan/Kg
8407 hot die-casting mold steel
88 yuan/Kg
DF-2 non-deformation and wear-resistant oil steel
35 yuan/Kg
ASSAB 88 special cold stamping die alloy steel
68 yuan/Kg
XW-5 high carbon and high chromium Tool steel
120 yuan/Kg
XW-10 high carbon high chromium tool steel
110 yuan/Kg
XW-41 High carbon and high chromium tool steel
110 yuan/Kg
XW-42 high carbon and high chromium tool steel
69 yuan/Kg
ASP60 powder high-speed steel
780 yuan/Kg
Japan Datong YK30
Advanced carbon tool steel
28 yuan/Kg
NAK80 pre-hardened high-quality plastic mold steel
53 yuan/Kg
PX5 high-quality plastic mold steel
26 yuan/kg
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DC-53 special cold punching die alloy steel
63 yuan/Kg
NAK55 pre-hardened premium plastic mold steel
52 yuan/ Kg
420 high-quality corrosion-resistant mirror mold steel
85 yuan/Kg
H3100 Sanbao red copper
98 yuan/Kg
p>Japan Hitachi SLD
Special cold die alloy steel
52 yuan/Kg
DAC (SKD-61) high quality hot work die alloy steel
56 yuan/Kg
DAC55 high-quality hot work die alloy steel
115 yuan/Kg
FDAC special heat-resistant die-casting mold steel
80 yuan/Kg
SKH-9 special high-quality high-speed steel
150 yuan/Kg
SKS3 wear-resistant non-deformation alloy tools Steel
28 yuan/Kg
SKD11 special cold stamping die alloy steel
44 yuan/Kg
HPM38 anti-corrosion mirror die steel
85 yuan/Kg
Germany Saast
Gleitz
2311 plastic mold steel
20 yuan /Kg
2738 Pre-hardened plastic mold steel <
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25 yuan/Kg
2316 hardened corrosion-resistant mirror mold steel
60 yuan/Kg
2083 corrosion-resistant mirror mold steel
48 yuan/Kg
2344
Hot work die-casting mold steel
60 yuan/Kg
2510 no Deformed wear-resistant oil steel
30 yuan/Kg
2379 special cold stamping die alloy steel
55 yuan/Kg
2083ESR corrosion resistance Mirror mold steel
65 yuan/Kg
2738HH high-quality plastic mold steel
29 yuan/Kg
2767 high-quality plastic mold steel
67 yuan/Kg
Pohang, South Korea
STD11 maximum thickness 200mm 40 yuan/KG
STD61 maximum thickness 600mm
55 yuan/KG
PSTW2 maximum thickness 230mm
55 yuan/KG
STP4 maximum thickness 600mm
23 yuan/ KG
The maximum thickness of STP4M is 1100mm
28 yuan/KG
Japan High Frequency
KDA1S high-quality hot work mold alloy steel
85
KAP65
High-quality plastic mold steel
25
KD11 special cold stamping die alloy steel
52
KPMAX
High-quality plastic mold steel
38
KRCX
Special cold stamping die alloy steel
60
KAP88
High quality plastic mold steel
50
KD21 special cold punching die alloy steel
63
KD12 special cold punching die alloy steel
55
KPH25K high-quality plastic mold steel
70...gt ;gt;