What is affecting precision injection molding?
Precision injection molding is affected by many related factors and environmental conditions, and the most basic ones are the basic factors of plastic materials, injection molds, injection molding processes and injection molding equipment. In the early stage of designing plastic products, first select the engineering plastics that can be needed according to their environment. Secondly, the appropriate plastic injection molding machine is selected for the selected plastic material, finished...
Injection molding process Process analysis
The plastic must be sufficiently dried before molding. When the moisture-containing material enters the cavity, it will cause silver-like ecchymosis on the surface of the workpiece, and even water decomposition will occur at high temperatures, resulting in deterioration of the material. Therefore, the material must be pretreated before forming, so that the material can maintain proper moisture. First, the mold temperature setting (1) The mold temperature affects the molding cycle and the...
The main role of injection and holding pressure in the injection molding process
What does it mean to hold pressure? The holding pressure means that the screw does not immediately retreat after injection, and pressure is still applied to the front melt. In the pressure holding stage, the plastic of the cavity can be reduced in size due to cooling shrinkage. If the gate is not frozen, the screw advances slowly under the pressure of the holding pressure, so that the plastic continues to be injected into the cavity for feeding. The role of injection The effect of the injection...
Problems that tend to occur during the injection moulding process and related solutions
First, the problem: the plastic is a wave. Cause: Due to the narrowness of the gate or other parts, the molten plastic pushes the solidified parts forward, and the surface is corrugated. Solution: 1. Increase the injection diameter 2. Increase the nozzle and mold temperature 3. Increase the height of the barrel 4. Increase the injection speed 5. Slow down the injection speed 6. Change the mold cooling water inlet position away from the gate 7. Expand the gate. Second, the problem: the plastic...
About the main features of UPVC and the injection molding process
1.What is UPVC material? UPVC is a mixture of an amorphous thermoplastic resin prepared by polymerization of vinyl chloride monomer with certain additives (such as stabilizers, lubricants, fillers, etc.). In addition to the use of additives, it is also possible to use a blending modification with other resins to make it have obvious practical value. UPVC has a high melt viscosity and poor fluidity, and even if the injection pressure and melt temperature are increased, the fluidity does not...
Special ceramic injection molding
Special ceramic materials such as silicon nitride have excellent properties such as high strength, high wear resistance, low density (light weight), heat resistance and corrosion resistance, and are suitable for manufacturing turbine feeder impellers, rocker burners, and auxiliary combustion. Ceramic parts for automobiles such as rooms. These components require complex shapes, high precision dimensions and high reliability. Intrinsic defects (cracks, pores, foreign matter, etc.) and surface...
Eleven considerations for PC injection molding
Excellent PC performance, high transparency, good impact toughness, creep resistance, and wide temperature range. Process characteristics of PC: melt viscosity has little sensitivity to shear rate, but has high sensitivity to temperature, no obvious melting point, high viscosity of melt, easy hydrolysis of resin at high temperature, and easy cracking of products. For these characteristics, we have to treat them differently: 1. To increase the fluidity of the melt, it is not necessary to...
Advantages and disadvantages between the extrusion and injection molding processes
The comparison between the extrusion process and the injection molding process is as follows: Concept comparison: Extrusion molding: Extrusion is also known as extrusion in plastic processing, and is used in the processing of non-rubber extruders by using hydraulic press pressure to extrude the extrusion of the mold itself. It refers to a processing method in which the material passes through the action between the barrel and the screw of the extruder, is plasticized while being pushed forward...
Problems that can arise during the use of masterbatches
In the case of sunlight, there are strips of pigmented strips in the product. This problem needs to be considered from the aspects of physical and mechanical properties of plastics and plastic molding processes: 1. The temperature of the injection molding equipment is not well controlled, and the color master cannot be thoroughly mixed with the resin after entering the mixing chamber. 2. The injection molding machine does not add a certain back pressure, and the screw mixing effect is not good....
Causes of excessive burrs and flying edges in injection molded products
What is the cause of excessive burrs in injection molding products? Excessive burr generally occurs on the split surface, that is, between the movable mold and the static mold, the sliding portion of the slider, the gap of the insert, the pore of the ejector rod, etc., and the excess melt is formed on the injection molded product . The burr, such a flash burr, can be leveraged during molding, which will further increase the burr of the flash, thereby causing partial depression of the mold, and...
The LCP molding process
The relevant knowledge of LCP injection molding is as follows: 1. Processing process of LCP material (liquid crystal polymer) Key points: The LCP material should be dried before use. The temperature is about 150 °C and the time is about 4~6 hours. The residual moisture content of the LCP after dehumidification should be below 0.02%, and the dew point should be kept at -35 °C. Note: It is recommended to use a vacuum dehumidifying dryer for the dryer. Do not use a general dryer. Because the...
Three major restrictions on injection molding plants
With the continuous development and progress of the market, the development of the plastics industry is constantly demanding more injection molding products, and the injection molding industry is also constantly developing. So far, although China's injection molding plant has achieved a series of advancements, it still faces some very important problems, which restricts the development of injection molding plants. First, the development is uneven. The direct development imbalance of the...
Allyl esters injection molding material characteristics and processing technology
Allyl ester resin Allyl esters are allyl based esters. Allyl esters based on monobasic or dibasic acids can be used as low tack monomers or thermoplastic prepolymers. They are often used as crosslinkers for unsaturated resins and are also used in the processing of reinforced thermosetting molding materials and high performance transparent materials. The resin retains its original electrical properties under high temperature and high humidity conditions, and the molded article has the advantages...
PA12 PS SA injection molding material characteristics and processing technology
PA12 Polyamide 12 or Nylon 12 Typical applications: water gauges and other commercial equipment, cable jackets, mechanical cams, sliding mechanisms and bearings. Injection molding process conditions: drying treatment: the humidity should be below 0.1% before processing. If the material is stored in the air, it is recommended to dry in 85C hot air for 4 to 5 hours. If the material is stored in a closed container, it can be used directly after 3 hours of temperature equilibration. Chemical and...
POM PPE injection molding material characteristics and processing technology
POM POM Typical Applications: POM has a very low coefficient of friction and good geometric stability, making it ideal for gears and bearings. Because it also has high temperature resistance, it is also used in pipeline devices (valves, pump housings), lawn equipment, etc. Injection Molding Process Conditions: Drying: If the material is stored in a dry environment, drying is usually not required. Melting temperature: homopolymer material is 190~230C; copolymer material is 190~210C. Mold...
PET PMMA injection molding material characteristics and processing technology
Typical application range of PBT polybutylene terephthalate: household appliances (food processing blades, vacuum cleaner components, electric fans, coffee utensils, etc.), electrical components (switches, motor casings, computer keyboard keys, etc.), automotive industry (heat radiator window, wheel cover, door and window parts, etc.). Injection Molding Process Conditions: Drying: This material is easily hydrolyzed at high temperatures, so drying prior to processing is important. It is...
PC/PBT/PE injection molding material characteristics and processing technology
Typical applications for PC/PBT polycarbonate and polybutylene terephthalate: gearboxes, automotive bumpers and required chemical and corrosion resistance, thermal stability, impact resistance and geometric stability The product. Injection molding process conditions: drying treatment: recommended 110 ~ 135C, about 4 hours of drying. Melting temperature: 235~300C. Mold temperature: 37~93C. Chemical and physical properties: PC/PBT has the combined properties of both PC and PBT, such as the high...
PA6/PA66 injection molding material characteristics and processing technology
PA6 Polyamide 6 or Nylon 6 Typical applications: Widely used in structural components due to good mechanical strength and stiffness. It has good wear resistance and is also used to make bearings. Injection Molding Process Conditions: Drying: Since PA6 absorbs moisture easily, special attention should be paid to drying before processing. If the material is supplied in a waterproof material, the container should be kept closed. If the humidity is greater than 0.2%, it is recommended to dry in hot...
PET, PP injection moulding process
PET Polyethylene terephthalate Typical applications: automotive industry, electrical components (motor housings, electrical couplings, relays, switches, microwave oven internal devices). Injection Molding Process Conditions: Drying: Drying before processing is necessary because PET is more hygroscopic. It is recommended to dry at 120~165C for 4 hours. The required humidity should be less than 0.02%. Melting temperature: for unfilled type: 265~280C; for glass filling type: 275~290C. Mold...
PC/ABS injection molding material characteristics and processing technology
PC/ABS Polycarbonate and Acrylonitrile Butadiene Styrene Copolymers and Mixtures: Typical Applications: Computer and Commercial Machine Housings, Electrical Equipment, Lawn Gardening Machines, Auto Parts Dashboards, Interior Finishes, and Wheel Covers. Injection Molding Process Conditions: Drying: Drying before processing is a must. The humidity should be less than 0.04%. The recommended drying conditions are 90~110C for 2~4 hours. Melting temperature: 230~300C. Mold temperature: 50~100C....
Characteristics and processing of PVC injection molded materials
PVC (polyvinyl chloride) Typical applications: water supply pipes, household pipes, house wall panels, commercial machine casings, electronic product packaging, medical equipment, food packaging, etc. Injection Molding Process Conditions: Drying: Drying is usually not required. Melting temperature: 185~205C. Mold temperature: 20~50C Injection pressure: can be as large as 1500bar holding pressure: can be as large as 1000bar injection speed: in order to avoid material degradation, generally use a...
Defects in injection molded products - colour differences
The color difference is also called discoloration, and the gloss is poor. The mechanism of chromatic aberration: Chromatic aberration is a common defect in injection molding . There are many factors affecting chromatic aberration, including raw material resin, color masterbatch, color masterbatch and raw material mixing, injection molding process, and injection molding machine. solution
How to solve the problem of air bubbles during the injection molding process?
The solution to the bubble phenomenon in the injection molding process is as follows: 1. According to the cause of the bubble, the solution has the following aspects: (1) When the wall thickness of the product is large, the outer surface is cooled faster than the center portion. Therefore, as the cooling progresses, the resin at the center portion is expanded toward the surface while being shrunk, so that the center portion is insufficiently filled. This condition is called a vacuum bubble. The...
Problems to be aware of during injection molding of transparent plastics
Due to the high light transmittance of transparent plastics, the surface quality of plastic products must be strict, and there must be no markings, pores or whitening. Fog, black spots, discoloration, poor gloss and other defects, so the raw materials, equipment throughout the injection process. Molds and even product designs must pay great attention to and impose strict or even special requirements. Secondly, because transparent plastics have high melting point and poor fluidity, in order to...
