Vacuum Casting Service

Polypropylene is a polymer formed by the polymerization of propylene. The composition and structure of polypropylene is crystalline polymer. Among the commonly used plastics, PP is the lightest material, with a density of only 0.90-0.91g/cm³ (less than water). Heat resistance is the best feature of PP among general-purpose plastics. The deformation temperature of PP is 80-110℃, and the product can be processed in boiling water at 100℃. PP has excellent stress crack resistance and good warpage fatigue life.

PP products have the advantages of lightweight, good toughness, and good chemical corrosion resistance. The disadvantages of PP are low dimensional accuracy, insufficient rigidity, poor weather resistance, ease to be damaged by “copper”, ease to shrink, ease to age, brittle, and warp after demolding.

Injection mold process conditions: Drying: If stored properly, it does not need to be dried.

Melting temperature: 220-250℃, not more than 250℃.

Mold temperature: 20-50℃, 40℃ is recommended.

A mold’s temperature is responsible for determining how much crystallization occurs.

Injection pressure: up to 1800bar.

Injection speed: Under normal circumstances, the use of high-speed injection molding can reduce the internal pressure to a minimum.

Polyethylene (PE) is a thermoplastic resin polymerized by ethylene. Polyethylene is colorless and non-toxic. And it feels like wax, has low temperature resistance (the lowest temperature can reach 70°C), good chemical resistance, and can withstand most acids and alkalis (not oxidation resistant). Insoluble in general solvents at room temperature, it has excellent electrical insulation and low water absorption.

Polyethylene is a polymer with a variety of structures and properties. It is mainly divided into LDPE, MDPE, HDPE, LLDPE, and performance ultra-high molecular polyethylene and low molecular polyethylene.

Injection conditions:

The temperature settings are as follows: injection nozzle 140-190°C, front part 140-200°C, middle part 130-180°C, screw speed 210-220 rpm, mold temperature 10-70°C, material tube temperature 150-210°C, back pressure 5 ~ 10 kg, injection pressure 360-500 kg / c㎡.

Polystyrene plastic (PS) refers to plastics containing styrene groups on the polymer chain, including ordinary polystyrene (GPPS), high-impact polystyrene (HIPS), expandable polystyrene (EPS) and metallocene Polystyrene (SPS) and so on.

General-purpose polystyrene is a thermoplastic resin, which is a shiny transparent bead or granular solid. The density is 1.04-1.09, the transparency is 88%-92%, and the refractive index is 1.59-1.60. The product has a melting temperature of 150-180°C, a thermal decomposition temperature of 300°C, a heat distortion temperature of 70-100°C, and a long-term use temperature of 60-80°C.

It is soluble in aromatic hydrocarbons, chlorinated hydrocarbons, aliphatic ketones and esters. In addition, it can withstand the influence of certain mineral oils, organic acids, alkalis, salts, low alcohols and their aqueous solutions. The water absorption rate is low, and the mechanical properties and dimensional stability can be maintained in a humid environment. Its optical performance is second only to acrylic resin. Excellent electrical performance, high volume resistivity and surface resistivity, not affected by temperature and humidity changes, and not affected by corona discharge.

Its main disadvantages are brittleness and easy cracking, low impact strength, poor heat resistance, cannot withstand boiling water, and can only be used at lower temperatures and lower loads. The lightfastness and flammability are poor.

It is possible to use the material directly without drying it in injection molding. But in order to improve the quality of the product, it can be pre-dried in a blast furnace at 55-70°C for 1-2 hours. The specific processing conditions are as follows: the barrel temperature is about 200℃, the mold temperature is 60℃80℃, the injection temperature is 170℃-220℃, and the compression ratio is 1.6 ~ 4.0. In order to eliminate internal stress, the molded product can be treated in an infrared lamp or a blast furnace at 70°C for 2 hours.

PC material is a widely used engineering plastic and belongs to amorphous plastic. It has good mechanical properties, such as high impact resistance, high tensile strength, excellent bending strength, low shrinkage, low thermal creep, high dimensional accuracy, good heat resistance, low-temperature resistance, etc. It can be used at temperatures of minus 60 to 120 degrees Celsius. The disadvantages are poor fatigue strength, brittleness, low solvent resistance and poor wear resistance.

PC material has excellent characteristics such as high light transmittance, high refractive index, high impact resistance and dimensional stability. Optical lenses made of optical grade polycarbonate can be used in cameras, microscopes, telescopes, optical testing instruments, etc., and can also be used in film projector lenses, copier lenses, infrared autofocus projector lenses, laser beam printer lenses, etc. As well as various prisms, polygon mirrors and many other office equipment and household appliances, its application market is very wide.

The fluidity of the plastic is poor, the mold gating system should be short and thick, a cold feed well is required, the gate size should be large, and the mold temperature should be high. If the temperature of the material is too low, it will cause short shots of the parts, the plastic parts are not shiny, the material temperature is too high, it is easy to overflow, and the plastic parts will bubble. Low mold temperatures result in low shrinkage and elongation, low impact strength, low bending strength, compression strength, and tensile strength. When the mold temperature exceeds 120 degrees Celsius, the plastic parts cool slowly, and the inner wall of the easily deformable viscous mold parts should not be too thick and uniform to avoid sharp corners and chipped materials.

The drying temperature of PC material is 120 degrees Celsius, and the drying time should be more than 4 hours. The mold temperature is usually 80 ~ 120 degrees Celsius. The injection temperature is 280 ~ 320 degrees Celsius. A slower injection speed and a larger injection molding pressure should be used in production.

Polyamide is commonly known as nylon, and its main varieties are PA6, PA66, followed by PA11, PA12, PA610, PA612, PA46 and so on.

Nylon has excellent mechanical strength, heat resistance, low friction ratio, self-lubricating, shock absorption and noise reduction, oil resistance, weak acid resistance, alkali resistance, general solvent resistance, good electrical insulation, self-extinguishing, non-toxic, odourless, good weather resistance, Poor dyeing and other advantages. It has high water absorption, which affects dimensional stability and electrical properties, but the combination of nylon and glass fiber is very good. Fiber reinforcement can reduce the water absorption rate of the resin, allowing it to work in a high temperature and high humidity environment.

Nylon is a crystalline plastic material with high melt temperature, narrow melt temperature range and poor heat resistance. PA does not gradually soften with the increase of heating temperature but softens in a narrow temperature range close to the melting point. Flow occurs as soon as the temperature is reached. PA is easier to absorb moisture. In the molding process of wet nylon, the viscosity drops sharply and the mechanical strength of the silver steel wire mixed with the foam product surface is reduced, so the material must be dried before it can be dried at 80-110 ℃ for 6 hours. However, please note that PA plastics are easy to cause discolouration if they are dried above 90°C.

PA has good fluidity and is easy to overflow, suitable for self-locking nozzles and heating. At the same time, due to the fast condensing speed of the solution, the material should be prevented from clogging the nozzles, runners, and gates and causing product shortages. The mold overflow value is 0.03, and the melt viscosity is more sensitive to changes in temperature and shear force, but more sensitive to temperature. In order to reduce the viscosity of the melt, we should start with the temperature of the barrel. It has a wide range of forming shrinkage, with prominent directions, and it is prone to shrinkage and deformation.

It is a blend of polycarbonate and ABS. As a result, ABS can be made more heat resistant, impact-resistant, and have stronger tensile strength; on the other hand, polycarbonate can be made cheaper, with lower melt viscosity, improved processing, and with less sensitivity to internal stress and impact strength. There is now flame retardant, glass fiber reinforced, electroplated, and ultraviolet resistant polycarbonate/ABS alloys available. Mainly used in the automotive industry, computers, copiers, electronic and electrical components, etc. PC/ABS alloy materials have been widely used in automotive decorative parts, lampshades, high-temperature electrical enclosures and other fields.

PC/ABS must be dried before processing. The humidity should be less than 0.04%. The recommended drying condition is 90mm 110℃, drying for 2h; the melting temperature should be around 23m ~ 300℃; the mold temperature should be 100℃ within 50 meters; the injection pressure depends on the plastic parts, and the injection speed has no special requirements. , But the higher the more appropriate.

Chemical and physical properties: ABS+PC has the comprehensive characteristics of PC and ABS, such as ABS is easy to process, and PC has excellent mechanical properties and thermal stability. The ratio of the two will affect the thermal stability of the ABS+PC material. The ABS+PC hybrid material also shows excellent flow characteristics. The shrinkage is about 0.5%. ABS+PC is a mixed synthetic modified engineering plastic. Among them, PC is polycarbonate, and ABS is a copolymer of acrylonitrile (A), butadiene (B) and phenylephrine (S). This modified plastic has better performance than simple PC and ABS. Such as improved impact resistance, heat resistance, hardness and so on.

PMMA acrylic plastic properties:

PMMA acrylic plastic is a hard and transparent material with a density of 1.19-1.22g/10cm³. The biggest feature of PMMA acrylic plastic is its high transparency and 92% light transmittance, which is the highest among plastics. The ultraviolet light transmittance is also as high as 75%.

PMMA acrylic plastic has good comprehensive mechanical properties. Its tensile strength, compressive strength, and flexural strength are higher than PE, PVC, PS, but its impact toughness is poor, so it is a hard and brittle material. PMMA has low heat resistance, glass transition temperature of 104℃, melting temperature of 160-200℃, thermal decomposition temperature of 270℃, easy to burn, the flame is blue when burning, the top is white, and it has a strong floral and fruity smell. And the smell of rotten vegetables.

PMMA has good dielectric and insulation properties, excellent arc resistance, and atmospheric aging resistance; PMMA has good chemical stability, can resist dilution of inorganic acids, intermediates, salts, and oils, but is not resistant to concentrated inorganic salts , Hot alkalis, ketones, chlorinated hydrocarbons, aromatic hydrocarbons, etc., will expand and break in alcohols, and have good corrosion resistance to ozone and sulfur dioxide gas.

PMMA acrylic plastic use: widely used in the manufacture of various optical glasses, such as lenses, prisms, mirrors, camera lenses, etc. And can make lamps, lighting equipment, instrument dials, dials, etc. In addition, it can also manufacture aircraft cabin glass, bulletproof glass, optical fiber, etc. In addition, adding fluorescent powder or pearl powder can make beautiful and beautiful products, which can be widely used in advertising decoration and handicraft production.

Polyvinyl chloride (polyvinyl chloride) is one of the most widely used plastics. Various additives are usually added to improve the performance of PVC materials, such as stabilizers, lubricants, processing aids, pigments, enhancers, etc.

PVC resin softens at a temperature close to that of its decomposition. It starts to decompose at 140°C, but decomposes faster at 170°C. In order to ensure the normal processing of PVC resin, the two most important process indicators are called decomposition temperature and thermal stability. The so-called decomposition temperature refers to the temperature at which a large amount of hydrogen chloride is released, and the so-called thermal stability refers to the time during which a large amount of hydrogen chloride is not released at a certain temperature (usually 190°C). PVC plastic will decompose for a long time at 100°C unless an alkaline stabilizer is added. If the temperature exceeds 180°C, it will quickly decompose.

PVC has the advantages of flame retardancy, high chemical resistance (resistant to concentrated hydrochloric acid, 90% sulfuric acid, 60% nitric acid, 20% sodium hydroxide), good mechanical strength, and electrical insulation.

The most common uses of PVC plastic materials include PVC profiles, PVC pipe, PVC hard materials and plates, PVC general soft goods, PVC packaging materials, PVC wallboards and floors, PVC consumer goods, PVC transparent sheets, etc. PVC plastic materials, PVC plastic materials , PVC plastic materials: PVC profiles, PVC pipes, PVC hard materials and plates, PVC general soft products, PVC packaging materials, PVC wallboards and floors, PVC consumer goods, PVC transparent sheets, etc.

Process conditions of the injection mold. Drying temperature: 80℃ within 2h, material tube temperature: 160-190℃, mold temperature: 30-60℃, molding shrinkage rate: 0.1-0.5%. The injection pressure can reach 1500bar, and the holding pressure can reach 1000bar. In order to avoid material degradation, an appropriate injection speed is required.

The main properties of POM are its hardness, high steel content, and wear resistance. POM has a low coefficient of friction and good geometric stability, so it is particularly suitable for manufacturing gears and bearings. The properties of POM make it appropriate for use in pipeline equipment (pipe valves, pump housings), lawn equipment, etc.

POM is a tough and elastic material with good creep properties, geometric stability and low-temperature impact resistance. Due to the high crystallinity of POM, the shrinkage rate is high, up to 2% ~ 3.5%. Different reinforcement materials have different shrinkage.

POM has a high heat distortion temperature, the heat distortion temperature of homopolymerization is 136℃, and the heat distortion temperature of copolymerization is 110℃. However, due to the difference in molecular structure, co-formaldehyde has a higher continuous use temperature. Generally speaking, the long-term use temperature of polyoxymethylene is about 100℃. UL specifies the long-term heat-resistant temperature of POM as 85-105°C. Mechanical properties: Since POM is a highly crystalline polymer, it has high elastic modulus, high hardness and rigidity. It can be used for a long time under the condition of -40 ~ 100℃. And it can withstand repeated shocks with little change in strength. Temperature and temperature changes do not greatly affect strength.

Injection molding conditions: POM does not need to be dried before injection molding. The melting temperature range is 190-220°C. By increasing the holding pressure during injection molding, the pressure drop can be reduced. The material will decompose at a high melting temperature. The screw speed should be appropriate, not too high, and the residue should be reduced; the appropriate mold temperature is (80mm 100℃), and the product demoulding temperature is relatively high, so pay attention to the protection work when disassembling the parts. POM should be processed under the conditions of medium injection pressure, medium injection speed, low material temperature and high mold temperature.

PEEK plastic is a special engineering plastic, which is a high molecular polymer composed of aryl, ketone bond and ether bond. It has many properties such as high temperature resistance, strong flame retardancy, and good chemical stability, so it is often used in construction machinery and aerospace products.

PEEK plastic has the advantages of strong heat resistance and high temperature resistance. The positive high temperature resistance of PEEK plastic is 260°C, and the heat distortion temperature is 160°C. If 30% glass fiber is added for modification, the heat distortion temperature can be increased to 280-300℃.

PEEK plastic has excellent electrochemical properties. Even in the high frequency range, the dielectric index and dielectric loss of 10HZ plastic are very small. The results show that the dielectric point constant under the PVA environment is only 3.2, and the dielectric loss is only 0.02.

It has excellent chemical stability and can withstand acids and alkalis. Almost any chemical reagent except concentrated sulfuric acid still maintains good stability at high temperatures.

It has excellent hydrolysis resistance and can be used for a long time even in a steam environment at 200-250°C.

In addition, PEEK plastic also has excellent flame retardancy, melt fluidity, thermal stability, corrosion, high strength and easy formability.

PEEK plastic is widely used in chemical industry, electronic equipment, automobile industry, aerospace and other fields because of its excellent high temperature resistance, heat resistance, high height and processability.

This material is formally known as polyphenylene sulfide. It is famous for its thermal stability and is widely used in special engineering plastics after filling and modification.

PPS is a special high engineering plastic with excellent properties such as high temperature resistance, flame retardant, corrosion resistance, weather resistance, dimensional stability, and excellent electrical properties. The transformed PPS is widely used as special engineering plastics, mainly in the fields of electronics and electrical appliances, such as transformer skeletons, high-frequency coil skeletons, plugs, sockets, junction frames, contactor drum plates, and various precision parts.

Heat resistance is PPS plastic: the heat distortion temperature exceeds 260℃, which is one of the highest temperatures of thermoplastic engineering plastics. The long-term use temperature is 220-240℃, and the short-term temperature can reach 260℃.

Chemical resistance of PPS plastics: At present, we cannot find any solvent that can dissolve PPS below 200°C, and has high corrosion resistance to inorganic acids, alkalis, and salts.

When exposed to high temperatures, high humidity, and high frequency, PPS plastic exhibits high surface resistivity, low breakdown voltage, low dielectric constant, and dielectric loss tangent, making it an excellent insulation material. After modification, it can also be made into a high-strength material with good electrical conductivity.

PPS plastic mechanical properties: strong rigidity, high surface hardness, excellent creep resistance and good fatigue resistance.

Injection conditions: The material is dried at 130-150°C for 3 hours, the barrel temperature is 280-330°C, 40%GF+PPS 300mm, 350°C, the mold temperature is 120-180°C, the injection pressure is 50-130V MPA, and the injection speed is medium.

The processed surface is the surface effect of the workpiece obtained by directly processing the workpiece with various machines and equipment without any post-processing. With the improvement of modern machinery accuracy, the surface quality of the workpiece is getting better and better. Although the processing line can be seen on the surface of the workpiece, it is actually very smooth, and the general processing surface quality can reach Ra3.2.

Anodizing is divided into ordinary anodizing and hard anodizing.

The conversion film formed in the process of metal anodization is wear-resistant, corrosion-resistant, and other functional or decorative properties on the metal surface in the electrolytic solution electrochemical treatment, and the treated part is used as the positive and negative corrosion-resistant materials.

The object of anodizing treatment can be aluminum and aluminum alloy, magnesium alloy, titanium and titanium alloy, etc. The anodic oxidation of aluminum and aluminum alloys is widely used in the market and is developing rapidly.

The main function of anodizing is to improve the hardness, wear resistance, corrosion resistance and surface coloring of the workpiece, and to protect and beautify the surface of the workpiece.

Sandblasting is a kind of high-pressure air as the power to spray abrasives into the workpiece that needs surface treatment at a high speed, thereby changing the post-treatment process of the surface of the workpiece. Due to the impact and cutting action of the abrasive on the surface of the workpiece, the working surface will get different roughness, which improves the mechanical properties of the working surface and improves the fatigue durability of the workpiece. Due to the influence of abrasives, very small pores are generated on the working surface, thereby increasing the adhesion between the workpiece and the coating and prolonging the service life of the coating.

The main functions of sandblasting are as follows:

In order to remove oil and rust, sandblasting can remove rust and other dirt on the surface of the workpiece, forming a certain rough surface on the surface of the workpiece, thereby improving the adhesion of the plastic powder and the paint film.

For processed workpieces, burrs on the surface can be removed by sandblasting to make the workpiece more beautiful.

For castings or heat-treated parts, sandblasting can remove oil and scale on the surface, improve the surface finish, and make the workpiece more beautiful.

Powder coating electrostatic spraying is to use static electricity to adsorb the powder coating on the working surface, and the powder is baked at high temperature to form a solid coating on the surface of the part.

Electrostatic powder spraying must first have an electrostatic generator to generate DC high voltage, a spray gun, a power supply system, and a powder recovery system to spray and atomize the powder. The workpiece to be sprayed should be grounded to the positive electrode, and the negative high voltage generated by the discharge needle gun connected to the powder outlet of the spray gun will generate corona discharge through the discharge needle. At this time, the negatively charged powder particles reach the surface of the workpiece under the action of static electricity and compressed air flow.

Due to the attraction of electrostatic force, the powder is uniformly adsorbed on the surface of the workpiece for a period of time without falling off. The workpiece enters the curing furnace, leveled, consolidated, and controlled humidity or time, and finally a tight, uniform, smooth and dense coating is combined with a firm workpiece. .

Powder spraying makes the surface of the product smooth, and the coating has strong acid resistance, alkali resistance, impact resistance and abrasion resistance. And can withstand strong ultraviolet radiation and acid rain for a long time, and the coating has no powdering, discoloration, falling off and other phenomena.

Black oxidation is an oxidation treatment on the surface of steel, mainly suitable for carbon steel and low alloy steel.

The black oxide heats the workpiece in a solution of concentrated alkali and oxidant (heating temperature is about 550°C), forming a dense oxide film (fe3-fe3) on the surface of the steel. The iron oxide film can isolate the air, prevent the internal steel from oxidizing, and achieve the purpose of corrosion resistance.

The steel is oxidized to form a protective oxide film with magnetic iron oxide (fe-fe2o3) as the main component. Its color is generally black or blue-black, and cast steel and silicon steel are brown. The oxidation treatment methods include alkali oxidation, alkali oxidation, acid oxidation and so on. It is often used for the protection and decoration of machinery, precision instruments, weapons and daily necessities.

Whether iron oxide can be oxidized with dense and smooth iron oxide, it is very important to choose a strong oxidizer. The strong oxidant is composed of sodium hydroxide, sodium nitrite and sodium hydroxide phosphate. When the color is blue, the steel part is treated with its molten liquid; when the steel part is treated with an aqueous solution, the steel part is black.

Surface drawing is a surface treatment method that forms lines on the surface of the workpiece by polishing the product and has a decorative effect.

The surface drawing process is to use drawing materials to make a decorative surface of metal stainless steel aluminum surface, and the surface drawing process is also a surface treatment method. It can make the surface clearly show every tiny silk mark, so as to make the metal frosted surface a fine brushed gloss product. Because wire drawing surface treatment can make the surface of the material show different textures and make the product more beautiful, wire drawing processing is becoming more and more popular nowadays.

There is no uniform classification and name for wire drawing. Usually divided into straight wire and wire according to the surface effect. Straight wire is also called silk thread; while silk thread is called snow pattern.

Electroplating is the use of electrolyte to electroplate other types of metals on the workpiece. Use electrolysis to attach the surface of the part to the metal film to prevent metal oxidation (corrosion), improve wear resistance, electrical conductivity, anti-reflection, corrosion resistance (such as copper sulfate), and improve aesthetics.

Electroplating metal or other insoluble materials, anodizing the workpiece, and cathode coating metal cations, form a coating surface on the surface of the workpiece. In order to eliminate the interference of other cations and make the electroplating uniform and firm, the electroplating solution should be used as the electroplating solution containing electroplating metal cations to keep the concentration of metal cations unchanged.