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Basic knowledge of plastic mold products and technical applic

 Zhilian Mould       2013-09-25 13:58      visitor 

Basic knowledge of plastic mold products and technical applications:


Our day-to-day production, life used to a variety of tools and products, large machine tool base, body shell, small embryo head screws, buttons and a variety of household appliances shell, all with the mold has a close relationship. The shape of the mold determines the shape of these items, the quality and accuracy of the machining of the mold will determine the quality of these products. Different because of a variety of products, materials, appearance, specifications, and use, the mold is divided into a casting mold, forging mold, die casting mold, stamping mold and other non-plastic mold, plastic mold.

    1) In recent years, with the continuous improvement in the strength and accuracy of the rapid development of the plastics industry and general engineering plastics, plastic products application range is also expanding, such as: household appliances, instruments and meters, construction equipment, automotive industry, and many other fields, the proportion of plastic products is rapidly increasing. A well-designed plastic parts can often replace multiple traditional metal pieces. Industrial products and consumer products, plastic of the trend is rising.


2) The general definition of the mold: in industrial production, with a variety of presses and a special tool is mounted on the press, through the pressure of metal or non-metallic materials, the desired shape of the parts or articles, such special tools are collectively referred to as the mold.

3) The injection molding process: mold tool is a production of plastic products. It consists of several groups of parts to the mold cavity, this combination successful. When injection molding, the mold clamping, the injection molding machine, the molten plastic is injected into the mold cavity, and cooling and shaping in the cavity, and then separated from the upper and lower molds via the top of the system, the top of the article from the mold cavity leaving the die, and finally the mold is closed again, the next injection, the injection molding process cycle.


4) The general classification of the mold: can be divided into the plastic mold and plastic mold:

    (1) A non-plastic mold: die casting, forging dies, stamping dies, die casting mold, etc..

    A. Casting mold - faucets, pig iron platform

    B. Forging mold - automobile body

    C. Stamping die - computer panel

    D. Die-casting mold - super-alloy cylinder block

    (2) plastic mold according to the different production processes and production products is divided into:

    A. Injection Molding - TV shell, keyboard button (the most common)

    B. Blow mold - drink bottles

    C. Compression molding mold - Bakelite switch, science bowl dish

    D. Transfer molding mold - Integrated Circuits products

    E. Extrusion die - glue tube, plastic bag

    F. Thermoforming mold - transparent molding packaging shell

    G. Rotational molding mold - soft dolls

     The injection molding method is most commonly used in plastic processing. The method is suitable for all thermoplastics and thermosetting plastics, obtained by the large number of plastic products is unmatched by other forming methods, as injection molds for injection molding tools, quality precision manufacturing cycle and injection molding process level in production efficiency, a direct impact on product quality, yield, cost and product updates, and also determines the ability to respond to market competition and speed.


5) According to the the pouring system type made different mold divided into three categories:

    (1) large outlet mold: runner and gate at the parting line mold with the mold release products, the most simple design, easy processing, low cost, large intake system so more people jobs.

    (2) fine outlet molds: the runner and gate is not parting line, the general directly on the product, so you want to design more than a group of outlet parting line, the design is more complex, more difficult processing, generally depending on the product requirements and selection fine nozzle system.

    (3) hot runner mold: such a mold structure, and the fine nozzle substantially the same, the maximum difference is the flow channel in one or more of the thermostat of the hot runner plate and the thermal jack mouth, without releasing of cold material, the flow channel and the pouring port directly on the product, so the flow path does not require stripping, this system is also called non-intake system may save raw materials, applicable to expensive raw materials and products require higher design and processing difficulties, high cost of the mold.

    Hot runner system, also known as hot runner system, mainly composed of hot sprue bush, hot runner plate, thermostat electrical box. Common hot runner hot runner single point and multi-point hot runner system has two kinds of forms. Single-point thermal gate directly with a single hot sprue bush molten plastic is injected into the cavity, it applies to a single-chamber single plastic mold gate; multi-point thermal gate hot runner plate the molten material Mycobacterium each sub hot sprue bush into the cavity, it applies to the single-chamber and multi-point into the material or multi-cavity mold.


The advantages of hot runner systems

    (1) outlet material, does not require post-processing the entire molding process is fully automated to save time, improve work efficiency.

    (2) the pressure loss is small. Equal to the temperature of the hot runner temperature and the injection molding machine nozzle, to avoid surface condensation phenomenon of the raw material within the sprue, the injection pressure loss is small.

    (3) outlet material reuse cause the plastic performance degradation, and no outlet material using a hot runner system, can reduce the loss of raw materials, thereby reducing the cost of the product. Uniform temperature and pressure in the cavity, the stress of plastic parts, uniform density, the smaller injection pressure, shorter molding time better than the injection system, injection products. For transparent pieces of thin pieces of large plastic parts or high-demand plastic parts to better display its advantages, and can use smaller models to produce a larger product.

    (4) hot nozzle standardization, serialization design, with a variety to choose from the nozzle head, good interchangeability. The unique design of the electric heating coil processing, to achieve uniform heating temperature, long service life. Hot runner system is equipped with hot runner plate, thermostat, compact design, species diversity, and easy to use, stable and reliable quality.

    The inadequacies of the hot runner system applications

    (1) the overall mold closes height increase, due to the retrofit hot runner plate or the like, the mold is the overall height increase.

    (2) thermal radiation is difficult to control, the hot runner runner of the biggest problems is the heat loss is a need to address the major issue.

    (3) presence of thermal expansion, thermal expansion and contraction to consider when we design.

    (4) mold manufacturing cost increases, higher prices of hot runner system standard accessories, affect the popularity of hot runner mold.

    Provide hot runner standard parts companies: DME, HASCO HUSKY, the EOC, FULLY the MASTER-TIP, INCOE etc..