ABS Injection Molded Parts

ABS is commonly known as acrylonitrile butadiene styrene, and Acrylonitrile Butadiene Styrene copolymers are copolymerized by three monomers of acrylonitrile-butadiene-styrene. The proportion of the three comonomers is different, and then blending with other plastics and additives will produce different properties, and at the same time greatly expand the use and performance of ABS materials. Such as heat-resistant grade, transparent grade, flame-retardant grade, electroplating grade, impact-resistant grade, reinforced grade, etc. The main products of Zhongwei Precision Machinery Co., Ltd. are nylon products, plastic products, ABS injection molded parts, rubber products, etc. Types of injection molding materials that can be processed: polyethylene (PE), polypropylene (PP), nylon (PA, PA6, PA66), polyoxymethylene (POM), ABS, polyurethane (TPU), polyphenylene sulfide (PPS), polystyrene Carbonate (PC), Polyetheretherketone (PEEK), etc.

Injection molding series: The injection molding workshop serves customers from the source, from plastic product mold and material design, development, mold trial, injection molding to a series of processes. Provide customers with excellent products.

Nylon processing series: The production and processing workshop has more than ten sets of advanced CNC automatic equipment such as CNC, turning and milling, and turntable. Provide customers with excellent products. Large-scale production of nylon wheels, nylon shafts, nylon sleeves, nylon gears, nylon strips, nylon plates, nylon blocks and other products.

Extruded nylon board series: The extruder provides customers with plastic boards, pads, guardrail nylon strips and other products.

Product Description

1. Implementation standards: the company strictly implements ISO9001, ISO14001, IATF16949, VDA6.3 certification, and products have passed ROHS, FDA EU certification, etc.

2. Product material standards: ISO, GB, ASTM, SAE, EN, DIN, BS, AMS, JIS, ASME, DMS, TOCT, GB

3. Main process: plastic injection molding, metal insert injection molding, investment casting, die-casting aluminum

4. Available materials for injection molding:

Processable nylon products, plastic products, ABS series; injection molding material types: polyethylene (PE), polypropylene (PP), nylon (PA, PA6, PA66), polyoxymethylene (POM), ABS, polyurethane (TPU), poly Phenyl sulfide (PPS), polycarbonate (PC), polyether ether ketone (PEEK) and 3D printing can be customized according to customer requirements.

Production Process

ABS is commonly known as acrylonitrile butadiene styrene, and Acrylonitrile Butadiene Styrene copolymers are copolymerized by three monomers of acrylonitrile-butadiene-styrene. The proportion of the three comonomers is different, and then blending with other plastics and additives will produce different properties, and at the same time greatly expand the use and performance of ABS materials. Such as heat-resistant grade, transparent grade, flame-retardant grade, electroplating grade, impact-resistant grade, reinforced grade, etc.

In terms of fluidity, the fluidity of ABS injection molded parts is between PS and PC. Its fluidity is related to injection temperature and pressure, and is more affected by injection pressure. Therefore, higher injection pressure is often used during molding to reduce Melt viscosity, improve mold filling performance.

ABS plastic has excellent comprehensive performance and high mechanical strength, and occupies a considerable proportion in the machinery industry, transportation, electronics industry, building materials, toy manufacturing and other industries, especially for slightly larger box structures and stress components.

1. Drying of ABS plastic

ABS plastic is hygroscopic and sensitive to moisture. It needs to be fully dried and preheated before processing to avoid silver threads and fog spots caused by water vapor. The moisture content of ABS raw materials should be controlled below 0.13%.

When drying, it should be dried for 2 to 3 hours in winter below 75 to 80 °C; in summer, it should be dried at 80 to 90 °C for 4 to 8 hours; if the production process is complicated, it can be dried for a longer time, about 8 to 16 hours. If conditions permit, the hopper of the machine can also be converted into a hot air hopper dryer to avoid secondary moisture absorption of ABS material in the hopper.

2. Injection temperature

The relationship between the temperature and melt viscosity of ABS plastic is different from that of other amorphous plastics. When the temperature rises during the melting process, the melt viscosity actually decreases very little, but when the temperature reaches between 220 and 250 ℃, it will continue to increase blindly. The thermal degradation of ABS material will increase the melt viscosity, make injection molding more difficult, and reduce the mechanical properties of the parts.

The heating range of ABS injection temperature is smaller than that of polystyrene and other materials. On some injection molding machines with poor temperature control, when the number of production parts reaches a certain number, yellow or brown coking particles will be produced. The fundamental reason is that plastic particles will stick to some surfaces in the screw groove that are not easy to scour under high temperature, and long-term high temperature will degrade and carbonize them.

Therefore, the operation of excessively high temperature may adversely affect the ABS material, and it is necessary to limit the furnace temperature of each section of the barrel.

3. Injection pressure

A higher injection pressure is used when ABS molten parts are injected, but a lower injection pressure can be used for parts with small size, simple structure and large thickness. During the injection process, the pressure in the cavity determines the surface quality and the degree of silver filiform defects.

If the pressure is too small, the plastic shrinks greatly, and there is a great chance of getting out of contact with the surface of the cavity, and it is easy to cause the surface of the workpiece to be atomized. Excessive pressure will increase the friction between the plastic and the surface of the cavity, resulting in sticking.

4. Injection speed

ABS materials generally use a medium injection speed to achieve better results, but use slow speed for fire-resistant grades and fast for heat-resistant grades. At the same time, if the surface requirements are high, it is necessary to use high-speed and multi-stage injection rate control.

5. Mold temperature

Because the ABS molding temperature is relatively high, the mold temperature is also relatively high. Generally, the mold temperature is adjusted to 75-85 °C. When producing parts with a large projected area, the fixed mold temperature is required to be 70 to 80 °C, and the movable mold temperature is required to be 50 to 60 °C.

In order to shorten the production cycle and maintain the stability of the mold temperature, after the parts are taken out, cold water bath, hot water bath or other mechanical setting methods can be used to supplement the time of cold fixing.

6. Back pressure

In general, the lower the back pressure, the better, usually the back pressure is 5bar, and the dyeing material needs a higher back pressure to make the color mixing uniform.

7. Material quantity control

In order to achieve stable quality and size of the parts, uniform surface gloss and color tone, it is necessary to control the injection volume to 50% of the nominal injection volume.

8. Residence time

At a temperature of 265°C, ABS can stay in the melt cylinder for up to 5 to 6 minutes. The flame retardant time is shorter. When the machine needs to be shut down, the set temperature should be lowered to 100 °C, and then the melt tube should be cleaned with general-purpose ABS. The cleaned mix needs to be placed in cold water to prevent further decomposition. If you need to change from other plastics to ABS, you need to clean the melt tube with PS, PMMA or PE first.

Overheating or the long dwell time of the melt tube will cause discoloration of the part.

9. Post-processing of products

Usually ABS parts do not need post-treatment, only electroplating grade products need to be baked at 70~80℃ for 2~4 hours to passivate the traces on the surface, and no release agent can be used, and it needs to be carried out immediately after removing the products Package.

10. Precautions for molding

After the flame retardant ABS is plasticized, its melt has a strong adhesion to the screw surface, which will cause decomposition after a long time. At this time, it is necessary to pull out the screw homogenization section and compression and wipe it, and regularly clean the screw with PS, etc.

Post Injection Molding Process

1. Processing equipment: CNC, WEDM, lathe, milling machine, drilling machine, grinder, etc.;

2. Surface treatment: For some products that require subsequent processing, we can provide surface treatment services to achieve the special purpose of customers. At present, we can provide degreasing, polishing, electroplating (gold, silver, nickel, tin, galvanized, etc.), anodizing, electrophoresis and other surface treatment services for precision parts.

Moulds and Inspection Fixtures

1. Mold service life: usually semi-permanent. (except for lost foam)

2. Mold delivery time: 10-25 days, (according to product structure and product size).

3. Tooling and mold maintenance: Zhongwei is responsible for precision parts.

Quality Control

1. Quality control: the defective rate is less than 0.1%.

2. Samples and trial run will be 100% inspected during production and before shipment, sample inspection for mass production according to ISDO standards or customer requirements

3. Testing equipment: automated visual inspection equipment can carry out 100% inspection of products, spectrum analyzer, golden elephant analyzer, three-coordinate measuring machine, hardness testing equipment, tensile testing machine.

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Application

ABS plastic is widely used in automotive, electrical and electronic, office and communication equipment and other fields. Today, in order to meet the special requirements of fire safety in the field of application (especially electronic and electrical products). Among them, the flame retardant technology of PC/ABS alloy has become a research hotspot. However, with the advancement of science and technology, the requirements for the environmental friendliness of materials are getting higher and higher, and the harm caused by traditional halogen-based flame retardants is becoming more and more obvious.

In engineering, ABS injection molded parts are widely used in engineering pipelines. In municipal projects, ABS pipelines can generally be used for pool bottom pipelines of projects with relatively high material requirements.

In addition, ABS plastics are often used in 3D printing, mainly because of the properties of ABS, which are characterized by heat resistance, impact resistance, low temperature resistance, chemical resistance, excellent electrical properties, and product dimensional stability. It is one of the most stable materials in 3D printing materials.

Knowledge points about ABS plastics, in addition to performance and uses, also include the coating process, injection molding process of ABS plastics, and local electroplating of ABS plastics.