Commonly used plastic raw materials POM

Polyacetal (POM) POM called "Race of steel", is a crystalline plastic, main properties are as follows:

1 POM is white plastic and shiny.

2 has good mechanical properties, hardness, high stiffness, good impact resistance and has excellent abrasion resistance and self-lubricating properties.

3 good resistance to organic solvents, stable performance.

4 after forming size is relatively stable, less affected by humidity. POM molding process to understand

1 POM small (smaller absorption rate <0.5%) moisture, generally does not dry before molding or short dry.

2 molding temperature range is narrow, poor thermal stability above 250 ℃ decomposition of formaldehyde monomer (melt darken) it alone to raise the temperature to improve liquidity and no harmful effect. Normal beer plastic feeding tube should adopt a lower temperature and a shorter residence time and increase the injection pressure can improve mobility and the quality of the product surface melt (melt flow rate of shear sensitive) temperature parameters: Before feeding tube 190-210 ℃, the feeding tube 180-205 ℃, after feeding tube 150-175 ℃ pressure parameters: the injection pressure is about 100Mpa, back pressure 0.5Mpa.

3 mold temperature control at 80-100 ℃ is appropriate (usually run hot oil)

4. POM cooling shrinkage large (2 to 2.5%) prone beer plastic "shrink", it must be used to extend the holding time to feeding.

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Precision injection molding and the common points of precision injection molding

Precision injection molding and the common points of precision injection molding

The characteristics of precision injection molding is: the size of the injection molded parts with high precision, small tolerance. To achieve the requirements of precision injection conditions must be met:

(1) the mold material is better, rigid, cavity dimension precision and template between positioning accuracy is higher, lower surface roughness.

(2) to adopt precision injection molding machine.

(3) to adopt precision molding process. (

4) to choose suitable for precision injection molding process of the material. Commonly used precision injection molding materials have several: POM, POM = CF (carbon fiber), PNM = GF (glass fiber), PA \ FRPA66 (enhanced PA), PC, etc.

Precision injection process can ensure the size precision injection molding is the important way to control the shrinkage of injection molded parts, including: thermal contraction, disguised contraction of molded parts, orientation and compressed contraction and elastic recovery.

Common injection molding features are: precision is not high, the size of injection molded parts are typically can be assembled into standard, requirements for the appearance of the injection molded parts is relatively high, if necessary, may use the second processing (oil, for example) to improve the appearance of defects. Ordinary injection molding don't need to use special precision injection molding machine, also do not need to specially designated materials, general common thermoplastics can be used to production. So ordinary injection molding technology is widely used in modern plastic industry.

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Mould inspection (acceptance) method and step

Mould inspection (acceptance) method and step

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How to acceptance of the mould

One, the products after the acceptance of mould manufacturing, passes through many times test, general small and medium-sized mold need to test 1 ~ 3 times, large and medium-sized mold need 3 ~ 5 times, particularly complex structure mould test number may also be more. Test how much the number of times and the equipment used and relevant operation quality engineer, is closely related to such factors as the quality of mold design, production. At the same time, to some extent reflects the technical level of a mold factory. Most can reflect comprehensively the mould is the last time the level of test samples are provided. Usually, send the sample order to check the result as an important basis when acceptance of the mould. Basic size samples are correct or not can reflect the mould manufacturing precision. Therefore, in the process of acceptance, the first to have the product acceptance. Acceptance at least plastic parts stamping or 16 hours after completing required by post-processing. Acceptance standard ambient temperature of 232, 506% relative humidity and dew point temperature of 21, atmospheric pressure of 890 ~ 1060 hpa, 1 m/s air velocity. If the actual environment is not standard, can be in under the conditions of both parties through consultation, or obtained by the numerical modify it with the length of the corresponding coefficient of expansion.

1. The basic size of products inspection made a sample, the first thing to observe its overall shape is correct, the basic model is in line with the product design thought. And then test the basic size of products.

2. The products with the size of the inspection products refers to products with the size between each other products or products and related components with dimensions, including local dimension and relative location of the overall size.

3. The trial assembly inspection When the basic size, dimension, cooperate with the dimensional check over, think it is in line with the design requirements, can try assembly inspection, this is very important in product inspection means, it can be validated to fit size, to verify this space curved surface.

4. Product appearance quality inspection After the pre-installed conform to the requirements, need on the apparent quality of the product to conduct a comprehensive inspection, then the table view of quality refers to the conditions, there is no common defects apparent quality meets the requirements.

5. Dynamic balance and static balance test For high speed components will go into action, the static balance test; For parts require high strength, resistance to impact test, strength, high temperature test, etc. Parts after full acceptance, acceptance to mould, mentioned above, can provide complete sample mould, can be regarded as basic reasonable on the whole structure. However, for other parts of the mold, the still have to carefully check, the mould structure parts machining precision, ways of panel board, the heat treatment method, factors directly affect the service life of mould.

1. Mold the appearance quality of a pair of mold in front, first observe its template mechanical processing level, below the template on the flat, flat grinding forming. Overall dimensions, has (2 ~ 5) mmX45 chamfering, can give a person a good impression, even reminiscent of mold internal processing quality must be superior. If the surface is rough, the length of the template not neat, although does not affect the intrinsic quality, but make the person is hard to imagine such a mold to produce high quality products.

2. Inspection of main parts of die after the acceptance of plastic parts, mold size basic confirmed correctly or not, mould dimensional tolerance of other aspects need further examination.

3. The status of the main structure Ensure the moving parts of the mould structure, mould set piece, inserts, sliders, and movement of the normal work of the wearing parts, etc.

4. Mold material processing in the mold design, the user can put forward special requirements of die materials, die standard parts heat treatment can be conducted in accordance with national standards.

5. Wearing parts and spare parts Each mold has its vulnerable parts, thus in the mold factory, equipped with spare parts. Some non-standard ask mold factory produce two at the same time, the change for factory

Commonly used plastic raw materials

Commonly used plastic raw materials

Acrylonitrile - butadiene - styrene copolymers (ABS)

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1 three components of the role: acrylonitrile (A) - to make products high surface hardness, improved abrasion resistance, heat resistance, butadiene (B) - to enhance flexibility, toughness to maintain elasticity and impact strength. styrene (S) - to maintain good moldability (fluidity, coloring) and maintain a rigid material (Note: According to the components derived from a variety of different specifications grades).

2. ABS plating with good performance, but also all the best performance plastics plating.

3 due to the effect of butadiene component, ABS representing GPPS becomes significantly improved impact strength.

4. ABS light yellow opaque materials, products, surface gloss.

5. ABS smaller shrinkage, good dimensional stability.

6 intolerant organic solvent, such as soluble in ketones, aldehydes, esters and chlorinated hydrocarbons to form an emulsion (ABS paste)

7 material blending performance (ABS + PVC) ~ improve the toughness, flame resistance, anti-aging ability. (APS + PC) ~ improve impact strength, heat resistance

ABS molding process to understand the

1 before the molding process to be fully dried so that the moisture content of <0.1% Dry condition: temperature 85 ℃ over 3 hours.

2. ABS liquidity is good, easy to produce beer plastic burr, the injection pressure is about 70-100Mpa, not too much.

3 tube temperature should not exceed 250 ℃.

4 mold temperature 40-80 ℃, the appearance of high demand products, mold temperature whichever is higher.

5 Take the injection speed, low-speed main; injection pressure according to the part shape, thickness, plastic material grade selection, usually 80-130Mpa.

Interior and exterior the car accessories use plastic type

Interior and exterior the car accessories use plastic type

General plastic on one car weight approximately 10% per cent of total vehicle weight. Which amount is the largest automotive polymer materials PP, representing about plastics for automobile by about 20% of the total. Plastics in the automotive industry occupies a pivotal position. The following are typical cases of application of plastics in the automotive industry:

Main varieties are for automotive plastics: PP, PU, styrene class (ABS,PS,SAN,SMA), PVC, PE etc. Polypropylene PP Max, very wide range of applications, representing about plastics for automobile by about 20% of the total. Its mainly because of lower production costs, while providing good processing properties.

For door assemblies, column cover, cockpit module threshold bumper moulding strip side guard, PP in a large number of applications in the automotive interior and exterior decoration, such as cockpit module, gate guard, bumper, and so on. Styrene-butadiene-acrylonitrile or ABS: application is more extensive, frequently used is ABS and its alloys, such as PC/ABS, and PVC/ABS.

Inside and outside the ABS in cars decorated with a wide range of applications, such as dashboards, barrier, lighting systems, wheel covers, door handles and other PC/ABS is often used as its alloy plating. Pu PU: polyurethane foams in car soft decoration has a irreplaceable status in plastic products, such as soft decoration dashboard, seats, door systems.

Application of polyurethane in automobile decorations interior and exterior: soft foam: semi-rigid foam cushion, backrest: dashboards, handrails, head of hard foam: roof lining elastic RIM: bumper. Polyamide (nylon) PA: polyamide types there are many, often used in automobiles are PA6 and PA66. For example, wheel covers, bumpers, intake manifold, pedal type, rear-view mirror.

And so on. Polycarbonate PC: Polycarbonate with excellent performance, high transparent, so is widely used in vehicle lighting systems.

Polycarbonate alloy, such as PC/ABS, PC/PBT inside and outside the vehicle bumpers made of ornaments is often used in PC/PBT often used in the premium-car.

These plastic types, we are a skilled application experience. But also all kinds of special plastics, PPT,PEI,PEEK,POM, and so on.

At the same time in medical devices, plastic products for life, and defense industry are involved.

If you encounter problems at any auto parts technology, applications or special plastic, see www.chinamoldmaker.org  or www.plastic-injectionmoulding.com

Mold History

Mold History

Since 1980, China passed the die 30 years of glorious history. With the development of economic globalization, more and more high-grade mold moving to China. Among them, Guangdong, Shanghai, Zhejiang, Jiangsu and most representative.

Guangdong is now no doubt that the main mold market, but also China's largest export and import Province die. 40% of the national output of more than die from Guangdong, currently in the country before ordering 10 companies in Guangdong occupies five.

However, it is worth mentioning that Shanghai, the international metropolis. While the rapid development of service industry, mold industry is also advancing with the times. Shanghai's existing mold more than 1,500 companies, employing 70,000 people, the annual production value of nearly 10 billion yuan, the annual average growth rate of over 20%. 2010 output value will reach 200 billion yuan; imports from the current 290 million yuan on the basis of 30% compression, will add about 700 million yuan output value of industry, exports reached $ 130 million, 600 million increase for the industry to turn yuan output value.

Moreover Shanghai mold industry will face six major industries and key industries, especially information (IT) industry and the automotive industry, to develop sophisticated IT industry magnesium alloy die casting, precision injection molding; mold coverage automobile industry, large parts die casting mold, precision stampings multitasking position progressive die. 2010 IT industry to achieve 85% localization of mold, auto mold to achieve 90% localization.

Shanghai mold industry has experienced 30 years of rapid development, our company in Shanghai is accompanied by the development of the entire mold trend step by step up to today. Our company has 10 years of experience in manufacturing plastic injection mold, from the beginning of 3-5 people in a small workshop, and now the factory area of 2,500 square meters, the annual output of more than 300 deputy dies. As experience is gained mold manufacturing and supporting industries increasingly sophisticated, and from quantitative to qualitative leap.

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Injection mold surface treatment

Injection mold surface treatment

What methods of injection mold parts surface treatment? In the working process of the injection mold parts on the surface of the working condition is bad, so it's easy to damage, therefore, need for some parts surface to surface treatment, for local enhancement.

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The effect of surface treatment (1) parts

In mould processing, surface treatment can make the parts for the following properties: increasing surface hardness, increase the compressive strength, abrasion resistance, improve the corrosion resistance and improve the sliding, etc.

(2) parts surface treatment methods

Surface treatment method are many, but for the mold parts, main methods of surface treatment are the following.

1) carburizing. Carburizing is to the steel surface infiltration carbon atoms. It is to put the parts into can release the active carbon atom medium, heat insulation, make activated carbon atoms permeability and the surface of the steel. Its purpose is to improve the surface of the carbon content, the subsequent heat treatment, the surface hardness increased, while the core remains resilient. Therefore, carburizing steel must be 0.15% ~ 0.25% (mass fraction), the carbon content of mild steel. Methods include solid carburizing, carburizing liquid carburizing and gas carburizing, is widely used gas carburizing.

2) nitriding (also called nitride). Nitriding is to the steel surface infiltration nitrogen atoms. Its purpose is to improve the parts table surface hardness, wear resistance, corrosion resistance and fatigue strength. At present, the most widely used method of nitriding is gas nitriding. It is to put the parts into the airtight furnace, the ventilation with NH3, heating to 500 ~ 600 ℃, the ammonia decomposition of reactive nitrogen atoms, the nitrogen atom is easy to be absorbed by the workpiece surface and spreading inside, forming a nitride layer, nitriding layer is 0.1 ~ 0.6 mm. Nitriding layer has high hardness and excellent dimensional stability, and can noticeably improve wear resistance and fatigue strength, corrosion resistance has greatly improved. In the mold processing, almost all steel nitriding processing. But it's a longer production cycle, high cost.

3) hard chromium plating. Hard chrome plating is will adopt the method of plating chromium plating on surface of parts, thereby gaining the surface of the hard and wear resistant, it to contain the abrasive plastic molding parts, hard chromium plating layer is very effective. In addition, the hard chromium layer can not only reduce the wear and tear, and can significantly improve the corrosion resistance of parts. Can also be used when repair the wear surface hard chromium plating method processing.

4) hard nickel plating. Hard nickel plating is to use chemical method will nickel plating layer on surface of parts. In the process, deposition of nickel layer does not use imposed by the electron flow, so you don't happen like electroplating on the edge, especially along the edge to form different thickness of electroplating film formation (edge) of the phenomenon. This method of nickel plating in the hole, opening and the place such as contour surface defects will not appear. The nickel plating layer often about 40 microns thick, it can form has good corrosion and wear resistance of the surface.

5) coated hard layer. In order to make the part surface with a high wear resistance and corrosion resistance, there is a new technology is in the surface coated with titanium nitride and similar material for grass-roots approach, it is easy to operate, and the effect is very good.

How to achieve efficient tooling and product quality control

Contemporary mold manufacturing industry is developing rapidly, the same rapid development as well as mold industry market competition. Under the requirements of the processing cycle shortened to lower the cost of the case, the accuracy requirements rise, not fall, so except in the case of funds, to maximize production capacity and processing equipment, quality control and efficient means of getting mold manufacturing enterprises to become can the key to winning the competition.

With the development of mold manufacturing, mold and product quality measurement and control is very important. My company from the early mold design involved in digital mapping, mold machining process measurement, repair mode measurements, to mold inspection measurement and post-mold repair measure; and product tryout, production, testing; from electronics small size mold the large car class molds and large molds aerospace industry measurement, quality testing mold used in measurement equipment, including the classic fixed high-precision coordinate measuring machine is not only, but also covers the projector and other equipment.

Cengcengbaguan mold quality, cutting-edge products using industry CPK (Complex Process Capability index acronym is used to represent the modern enterprise process capability index. Process capability is the maximum allowable ratio of process performance and process variation range of normal variation) management system to ensure product quality! Efficient mold, product quality control. About Our specific quality testing and CPK use of the program, please refer to www.chinamoldmaker.org or visit our website www.plastic-injectionmoulding.com

The application status of plastics in medical apparatus and instruments

The application status of plastics in medical apparatus and instruments

Medical equipment involves multiple sectors pharmaceuticals, machinery, electronics, plastics, etc., in which the rapid development of plastic medical devices. Since the 1930s, people first used synthetic polymer materials - since celluloid film is made as an artificial kidney dialysis membrane used in clinical success, polymer materials are gradually replacing traditional inorganic materials such as metals, glass, ceramics, phosphorus gray stone for the preparation of medical devices.

This is because: (a) a polymer material with good mechanical properties and chemical stability, more suitable for medical use;

(2) a rich source of polymer materials, inexpensive, disposable medical supplies for made ​​to avoid the traditional material products due to high prices and had to repeatedly use disinfection and problems caused by secondary infections;

(3) or more easily modified plastics have been good tissue compatibility, blood compatibility of products;

(4) made ​​of plastic low cost, suitable for a variety of molding methods, ease of processing into complex shapes and the development of new medical products.

Compared with ordinary plastics, medical plastics require higher:

(1) Since most toxic monomers and oligomers, so medical plastics are strictly limited to the residual of the foregoing;

(2) plastic in the polymerization process inevitably come into contact with the reactor, metal catalysts, which often contain trace metal ions, according to the medical plastics GB requirement for zinc, lead, cadmium, copper, barium, tin and other metal ions residual cases are clearly defined; resin

(3) requirements for medical plastics with high purity, narrow molecular weight distribution;

(4) plastic processing or modified in the process need to add various additives, such as the amount of plasticizer in PVC medical products often as high as 30-60%, thus requiring maximize the use of toxic chemicals, to prevent long-term use or reduce the precipitation of additives to affect product performance and treatment;

(5) In accordance with the requirements of medical plastic, often need to make products with surface hydrophilicity, anti-radiation sterilization and other functions.

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Injection molding cycle

The time required to complete an injection molding process molding cycle, also known as the molding cycle. It includes the following several parts:

Injection molding cycle

Molding cycle: molding cycle directly affect the labor productivity and utilization rate of equipment. In the process of production, therefore, should be on the premise of guarantee quality, try to shorten the molding cycle time of all. In the molding cycle, with injection time and cooling time is the most important, they have a decisive influence on the quality of products. Mold filling time of injection time is directly on the mold filling rate, for the production of molding time is about 3 to 5 seconds. Injection time of the holding time is the cavity pressure time, plastic in the large proportion in the whole injection time, usually about 20-120 seconds (thick parts can be up to 5 ~ 10 minutes). At the gate before freezing, melting the holding time of how many, dimensional accuracy of products are affected, if in the future, no effect. The holding time are the most value, known it depends on the material temperature, mold temperature and the mainstream and the size of the gate. If the mainstream way and the size of the gate and process conditions are normal, usually is to get products shrinkage range minimum pressure value shall prevail. Cooling time is mainly decided by the thickness of products, thermal and crystallization properties of plastics, and mould temperature, etc. The end of the cooling time should be in place to ensure that products mold release when not cause changes for the principle, general about cooling timeliness between 30 to 120 seconds, cooling time is too long is not necessary, not only reduce the production efficiency, the complex parts will also cause demoulding difficulty, even the forced demoulding will produce mold release stress. Other time of the molding cycle is linked to the production process is continuous and automatic and continuous and the degree of automation and so on.

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Injection operator processing requirements

Injection operator processing requirements

A, plastic product quality requirements

1, the injection forming of product, must ensure that the product structure is complete, there is no less material, more material phenomena.

2, product surface bright, uniform chromaticity, full.

3, product surface is not filled with flowers, impurities, defects such as black spots.

4, the product shape neat, there is no deformation, distortion, and the internal products are obvious bubble phenomenon.

5, the product can cooperate with relevant parts is normal, without external force cannot be separated.

6, the assembled product to need, after assembling the operators need to introspection, to ensure that products meet quality requirements. There is no

Not installed in place, packing, and have a fracture phenomenon.

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Second, the plastic products trimming

1, the product of the inlet with trimming knife cutting, cutting mouth who can not have express white appearance.

2, when trimming knife trimming, forcibly when repairing products shall repair products outside introversion, resistance force direction is not allowed to have another hand

Block.

3, product trim on the handle of the strength should be uniform, can guarantee a hard cut products as much as possible, long group of front, middle

Not stagnation, a fix to the end, to ensure that after trimming the edges of the beautiful appearance.

4, the surface of the product by trimming does not allow defects wavy lines and uneven.

5, to remove the inlet area, trimming should level off, allow the phi 10 from minor scratches, trimming to improper

Other parts are not allowed to have should be trimming undeserved cause scratch defect.

6, to put front height is greater than 0.2 mm should be handled for trimming (unless adjust injection parameters to solve), especially in the production

Product outline on the edge of the phi front must be removed.

7, for different products, it is suggested that should use different types of trimming knife, to ensure product quality, improve the efficiency of trimming. 8, don't allow should trim other qualified on the surface of the damage caused by improper operation (such as good surface scratch, cut, etc.).

Three, product storage and handling

1, product stacked on the pallet height should not exceed 1.2 mm, the number of the same specifications each building products must be the same, with winding mode finally. For small products in the turnover box, bottom in turnover box height should be 10 cm, turnover box the loading weight of not more than 25 kg.

Injection molding Tips

Injection  molding Tips

Injection molding process, wherein the thermoplastic resin is injected into a mold, cooled and hardened in front of the machine. The end result is a series made of the same plastic articles. Injection molding may be used to make industrial products such as automotive parts or smaller products, such as a plug receiver, camera parts or containers.

Choose your resin in advance

Although you can wait until the last moments of the injection molding process of the game, select and use your resin, the resin earlier picking speed up the process and save time and money. Already considering using resin helps simplify the design of any further design choices along the way, at a later stage, and to reduce the need for additional work. For example, one product has a very thick part of the ABS resin, which is likely to dent the mold thick around the place is not a good idea. Similarly, selecting a set mold polystyrene is a bad idea, thinner regions will simply break due to the brittle nature of the material. A prototype, the freedom to change the resin, if necessary.

Avoid sink marks

Dent of the surface occurs in the mold thicker portion recess or void. When the occurrence of dents, thickness of the resin is cooled at different speeds set portion hardens inside the external heat is still in a molten state, and the edges of the coolness of the contract, which creates a dimple or depression. Industry professionals a trick used is the hollowing out of the thick set of part or core strength and durability still be avoided dent.

Avoid premature freeze

Prior to occur when the thermoplastic resin is cooled and solidified prematurely hardened, the mold has been completely filled. A possible solution is to increase the temperature of the resin, until the mold has been filled, which will keep the thermal material. Another tip is to improve the injection speed, should ensure a thermoplastic resin has fully pumped into the mold before setting. Other tips to avoid premature solidification include mold temperature, injection pressure and to improve the high melt flow rate less than the MFI (melt flow index) level.

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