Nylon material properties

A, classification and properties of nylon classification:

1, according to the number of carbon atoms of diamine and dibasic acid, composed of two monomer synthetic nylon: 46, 66, 610, 66, 613, 1010, 1313,

2, according to the monomer containing named in the number of carbon atoms: nylon 4, 5, 6, 7, 8, 9, 11, 12, 13

Second, features:

1, nylon has good toughness, self lubrication and wear resistance, chemical resistance, gas permeability, and oil resistance, non-toxic, and the advantages of easy coloring, so the nylon is widely applied in industry.

The technological characteristic of the rheological properties of nylon, nylon: most for crystalline nylon resin, when the temperature exceeds its melting point, the melt viscosity is small, the melt liquidity is wonderful, should prevent excessive edge. Due to the melt condensation speed at the same time, should prevent material blocking the nozzle, runner and gate products caused by insufficient phenomenon. Mould overflow boundary value of 0.03, and the melt viscosity are sensitive to temperature and shear stress change, but is more sensitive to temperature, lower viscosity of the melt from the cylinder temperature first.

Four, nylon nylon absorbent, water absorption and the dry wet nylon in molding process, characterized by viscosity fell sharply and mixed with surface silver bubble products, the products obtained mechanical strength decreased, so the material must be dry before processing.

Crystalline: in addition to the transparent nylon, nylon mostly for the crystallization of polymer, high crystallinity and tensile strength, abrasion resistance, hardness, lubricity, and so on a performance improvement, thermal expansion coefficient and water tends to decline, but bad for transparency and impact resistance. Had a greater influence on the mold temperature on the crystallization, mould temperature high crystallinity, die temperature bottom end of crystallinity.

Shrinkage: similar to other crystalline plastics, nylon resin shrinkage rate larger problems, the maximum nylon with crystallization of contraction, when products crystallinity big products shrinkage increases, in the process of forming lower mold temperature, increasing injection pressure, lower temperature will decrease the contraction, but the internal stress of products is more easy to deformation. PA66 shrinkage rate of 1.5 to 2%

Molding equipment: nylon molding, mainly pay attention to prevent "nozzle flow delay phenomenon", so the nylon material processing generally choose the self-locking type nozzle.

Products and moulds:

1, the products of wall thickness Do so than for 150-200 between nylon, nylon products wall thickness below 0.8 mm generally between 1-3.2 mm, and the products of contraction associated with products of wall thickness, the thicker the thickness contraction.

2, exhaust nylon resin overflow boundary value is about 0.03 mm, so the vent groove should be controlled below 0.025.

3, mold temperature products thin wall molding mould heating control or require high crystallinity, required products have certain flexibility of general use cold water temperature control.

Third, molding technology of nylon

Cylinder temperature: as nylon is a crystalline polymer, so obvious, melting point of nylon polymer in the injection molding of the selected material barrel temperature with the performance of the resin itself, equipment and products of shape factors. Nylon 6 melt temperature is 225 ℃ at the bottom, nylon 66 is 260 ℃. * due to the poor thermal stability of nylon, should not be so high temperature for a long time to stay in the cylinder, lest cause the material color is yellow, due to the liquidity of nylon is better at the same time, the temperature over flow quickly after its melting point.

Injection pressure: nylon low melt viscosity, good fluidity, but the cooling speed faster, the complex shape and wall thickness thinner products are easily appear shortage problem, so still need high injection pressure. Pressure is too high, usually products will overflow edge problems; Pressure is too low, products can produce corrugated, bubble, obvious welding scar or lack of product defects, most varieties of nylon injection pressure does not exceed 120 mpa, the general selection within 60-100 mpa is meet the requirements of most of the products, as long as the products don't appear bubbles, defects such as dents, generally do not want to use high pressure maintaining pressure, so as not to cause internal stress increased.

Injection speed: for nylon, injection speed for quick profit, can prevent the ripples caused by too fast cooling, molding shortage problem. Fast injection speed impact on the performance of the products is not prominent. Mold temperature mold temperature on the crystallinity and the molding shrinkage has certain influence, anti-embrittlement high crystallinity, wear resistance, hardness and elastic modulus increased, decreased water imbibition, products molding shrinkage rate increase; Low mold temperature low crystallinity, good toughness and elongation is higher.

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The importance of mold to industry

Mould process is widely used in industrial production, is the basic industry of national economy. Commonly used in modern production, the product parts stamping, Die-casting, forging forming methods of forming, extrusion forming, plastic injection processing to meet the requirements of the product parts. Mould machinery is used for molding tools, this tool has all parts, different mould made up of different parts. It is mainly by the changes of the molding material physical state to implement items shape processing. In blanking, forming punching, die forging, cold heading, extrusion, powder metallurgy parts suppression, pressure casting, as well as engineering plastics, rubber, ceramics and other products of compression or injection forming, the action of external force to make blank into a specific shape and size of the stamping tools.

Industrial production mould is the important foundation of manufacturing technology and equipment, industrial products mass production and new product development is inseparable from the mold, with mold production parts of four high low (high accuracy, high complexity, high consistency, high productivity and low energy, low consumables) make the industry more and more important status in the manufacturing of dies. People common industrial products are 60% - 90% of the parts need to use die forming. Mould precision is low, the product quality is poor, die life is low, the product cost is high. Modern mould has become the technology intensive and capital intensive industry, its relationship with the new and high technology has become a mutual relying on, on the one hand mold directly serve for new and high technology industrialization indispensable equipment, on the other hand the mold itself is a large number of new and high technology, so the mould manufacturing has become an important part of new and high technology industries. By rapid die forming parts, high quality, low consumption, environmental protection reflects the national strategy of sustainable development and the scientific outlook on development.

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Precision injection mold industry development is getting better and better

Many industry rising to the requirement of the mould, so precision mold industry development gradually hot up, with the vigorous development of the electronic information industry and traditional industry informatization modification, plastic mold market prospect of a vast, global high-grade, precision plastic mould market is in short supply situation.

In recent years, China plastic mold manufacturing level has been improved greatly, the production of large single set weight of the plastic mould has reached more than 50 t, the accuracy of precision plastic mold has reached to 3 cm, already can produce a multi-cavity mold plastic mold cavity encapsulation molds, 7800 high-speed molding aspect has been able to produce extrusion speed of more than 4 m/min high-speed plastic different profile extrusion die and the main profile double co-extrusion die cavity.

Affected by the variety of national policy and the continuous expansion of market space, car industry, IT industry, packaging industry momentum very rapidly in recent years, not only has made great development in terms of capacity, but also in the aspect of the industry's high-end has a great progress, therefore, in the industry including the three aspects has a strong mold needs. Part of automobiles, IT products of plastic parts need to be all through the molding, eventually to become a finished product for sale.

With the rapid development of plastic industry and general engineering plastics in such aspects as strength unceasing enhancement, the application range of the plastic products are also constantly expanding, the amount of plastic products is also rising. More information on www.chinamoldmaker.org www.cnmoulding.com

Automobile industry drives the mold production

Auto mould is still the most widely , the field of industry development is rapid, every car need thousands of pair of mould, auto makers has formed with the closely matching mould enterprise development, research and debugging technology, production of strategic alliance. Cars are increasingly high strength plate in order to reduce weight, also for some ultra high strength plate hot forming and the corresponding hot forming mould has naturally become the development trend.

Mold to use plastic lighter will increase and the development of new materials, including all kinds of new plastic, modified plastic, metal, plastic, magnesium alloy, composite material, and so on, this requires a new forming technology, which also requires that have adapted to the new mold. According to network mold, China mold in the future in the market, the proportion of total plastic mold in the mold will gradually increase, its development speed will be higher than other mold.

"Mould to elegant, requires good appearance generous, internal defects, this would require careful, precision mould with high quality. At present, the refinement has a big gap, refinement is often ignored by some companies, the results fell short." Company, I think that the mold fast and efficient production, this mould enterprises try to shorten the mold production cycle, to mold the user mould as soon as possible, on the other hand is more important, the user can you provide a mold to production products more quickly and efficiently. Such as more than a multi-cavity mould production, laminated mold, forming time and make good use of hot runner technology to shorten the use of multilayer composite technology, mould decoration technology, highlights non-mark injection molding technology, testing technology and process of composite technology and transfer technology and so on, at the same time stamping forming process intelligent also requires intelligent mold to adapt.

　　

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electrical and electronic engineering plastics application

Compared with general plastics, engineering plastics has more excellent mechanical properties, electrical properties, chemical resistance, heat resistance, abrasion resistance, dimension stability, etc; Compared with metal materials, engineering plastics has the advantages of light weight, small energy consumption when molding. Engineering plastics has become the world's plastics industry developing the fastest growing materials

In Asia, engineering plastics are mainly used in electrical industry, more than 50%, and in Europe and the United States, engineering plastics are mainly used in automotive industry. From 1998 to 1998 China engineering plastics consumption annual average increase rate of 26% (see chart 1). Is expected in the next few years the growth rate of 15% ~ 18%. As China's electrical products exports increased year by year, the dosage of the engineering plastics is on the rise. Although the current domestic product technology content and added value is very low, but this does not affect the huge demand for engineering plastics manufacturing. Under cost pressure, requirement for material localization is more and more obvious, which provides a broad prospect of application for engineering plastic.

Commonly used on electrical and electronic engineering plastics

1. The PA(nylon)

PA is characteristic of good toughness and high mechanical strength, wear resistance, but easy bibulous deformation. Mainly used in the manufacture of machine tools in electrical and electronic appliances, air switches, connectors, all kinds of coil skeleton; Tape recorder, video camera, video camera, DVD, OA equipment, machine core, skeleton, supporting parts, gear, wheel; As well as the cable bracket, brace, gear, wheel; And the cable sheath, household appliances, small appliances, etc.

2. PC (polycarbonate)

The advantage of PC is transparent, high impact strength, good mechanical strength, size stability. Drawback is not resistant to solvents, easy to produce stress cracking. Mainly used in the transparent parts of the electrical appliances (such as window, shell, panel, etc.).

PC/ABS alloy is more used in electrical appliances shell, display case, mobile phone shell, shell, batteries, laptop charger shell; Cable connector, OA equipment and small home appliance products.

3. The POM (POM)

POM has superior mechanical properties. Wear resistance and size stability, resistance to chemical corrosion, fatigue resistance, but poor thermal performance, flammable easy decomposition, notch sensitivity. Mainly used in electrical appliances, instrument structure, all kinds of gear, CAM, driving wheel, the recording tape axis core, floppy disks, the doors of machine tool electrical appliances.

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