Basic knowledge of plastic mold

Basic knowledge of plastic mold
1,Introduction
 Our everyday life and production used a variety of tools and products to the large to the machine base, the body shell, an embryo as small screws, buttons and various household appliances in the shell, all have a close relationship with the mold. The shape of the mold determines the shape of these products, the quality and precision mold processing will determine the quality of these products. Material for various products, appearance, specifications and use of different mold into the casting mold, forging mold, die casting, stamping die and other non-plastic mold and plastic mold.
In recent years, with the rapid development of plastics and general industrial and engineering plastics in the intensity and precision, continuous improvement, plastic products, also expanding range of applications, such as: household electrical appliances, instruments, construction equipment, automotive, Japan with hardware and other fields, the proportion of plastic products is rapidly increasing. A well-designed plastic parts can often replace the more traditional metal parts. Plastic household products, industrial products and the trend is increasing.
2, the general definition of the mold: in industrial production, mounted by a variety of presses and press the special tools, through pressure or non-metallic materials, the metal shape of the required parts or products, this special tool referred to as mold.
3, the injection molding process Description: Mold is a tool for the production of plastic products. It consists of several groups of components parts, the combination of the successful mold cavity. Injection, the mold clamping in injection molding machine, molten plastic is injected into the mold cavity forming and cooling in the cavity shape, and then separated from the upper and lower mold through the top of the system will be products from the top of the left mold cavity, the mold is closed again, the last the next
injection, the injection molding process is conducted in cycles.
4, the general categories of mold: Mold can be divided into plastic and non plastic mold:
(1) Non-plastic molds are: die casting, forging die, die stamping, die casting molds.
A. Casting mold – faucets, cast iron platform
B. Forging Die – Auto Body
C. Stamping die – computer panel
D. Die casting mold – super alloys, cylinder
(2) Plastic mold production technology and production based on the different products are divided into:
A. Injection Molding – TV cabinet, keyboard buttons (the most common)
B. Blow mold – drink bottles
C. Compression Molding – bakelite switch, science bowl dish
D. Transfer Molding – IC products
E. Extrusion die – glue tubes, plastic bags
F. Hot Forming Die – transparent shell molding packaging
G. Rotary molding – soft toy doll

◆ injection molding is the most commonly used plastic processing method. The method is applicable to all parts of thermoplastics and thermosetting plastics, plastic products obtained large quantities unmatched by other molding methods, injection molding process as one of the main tools for plastic injection molds, precision in quality, manufacturing cycle and injection molding process in the level of production efficiency, etc., directly affect the product quality, yield, cost and product updates, but also determines the competition in the market responsiveness and speed.
◆ injection mold by a number of steel plates with the various component parts, and basically divided into:
A molding device (die, punch)
B positioning device (guide post, guide sleeve)
C fixtures (the word board, code-mode pits)
D cooling system (carrying water hole)
E constant temperature system (heat pipe, heater)
F flow system (pump nozzle holes and flow channel grooves, flow hole)
G top of the system (thimble, top stick)
5, the system according to the different type of gating system can mold into three categories:
(1) large outlet die: the flow channel and gate at the parting line, with products in the mold with the mold release time to design the most simple, easy processing, low cost, so the more people using a large nozzle system operation.
(2) fine nozzle mold: flow channel and the gate is not the parting line, usually directly on the product, so much to design a set of outlet parting line, the design is more complex, more difficult process, generally used depending on the product requirements fine nozzle system.
(3) hot runner mold: This mold structure and fine nozzle substantially the same, the biggest difference is that the flow in one or more of a constant temperature of the hot runner plate and heat pump mouth, no cold material ejection, and the water flow port directly on the product, so the flow does not require stripping, this system is also known as non-outlet system can save raw materials for more expensive raw materials, products require a higher situation, design and processing difficulties, mold costs are higher.
Hot runner systems, also known as the hot runner system, mainly by the hot sprue bush, hot runner plate, temperature control electric box composition. The most common hot runner hot runner system has a single point and multi-point thermal gate two forms. Single hot runner gate is a single set of heat directly to the molten plastic injected into the cavity, it applies to a single gate single cavity plastic mold; more hot runner hot runner plate through the molten material to each branch sub-set of the hot runner and then go to the cavity, it is more suitable for feeding a single cavity or multi-cavity mold.
◆ the advantages of hot runner system
(1) No outlet material, no post processing, the whole forming process is fully automated, saving time and increasing efficiency.
(2) the pressure loss is small. Hot runner injection molding machine nozzle temperature and the temperature are equal, to avoid the material within the sprue surface condensation, the injection pressure loss is small.
(3) outlet material re-use of plastic will degrade performance, and use the hot runner system has no outlet material can reduce the loss of raw materials, thus reducing product costs. Temperature and pressure in the cavity uniformly stress the small plastic parts, density, injection pressure in the smaller, shorter molding time, the injection molding system than the general and better products. For the transparent parts, thin pieces, large plastic parts or plastic parts with high requirements to better demonstrate its advantages, and smaller models can produce more products.
(4) thermal nozzle is standardized, serialized design, with options for nozzle head, good interchangeability. Unique design and processing of electric heating coil, can be achieved even heating temperature, long service life. Board with a hot runner hot runner systems, temperature control, etc., design sophistication, more variety and easy to use, stable and reliable quality.
◆ Application of hot runner system inadequacies
(1) to increase the overall height of the mold is closed due to installation of hot runner boards, die overall height has increased.
(2) thermal radiation is difficult to control, hot runner runner biggest problem is the heat loss is a major issue to be resolved.
(3) there is thermal expansion, thermal expansion and contraction of our design issues to consider.
(4) mold manufacturing costs, prices of hot runner system, the higher standard accessories, the popularity of hot runner molds.
◆ Provide hot runner standard parts companies: DME, HASCO, HUSKY, EOC, FULLY, MASTER-TIP, INCOE other companies.