Plastic blow molding - the process of making plastic molds
Plastic blow molding - the process of making plastic molds
1, the general definition of the mold: in industrial production, with a variety of presses and special tools installed on the press, through the pressure of metal or non-metal materials to make the required shape of the parts or products, this special tool is collectively known as the mold. Plastic blow molding
2, injection molding process: mold is a tool for the production of plastic products. It consists of several sets of parts in which the mold cavity is formed. When injection molding, the mold is clamped in the injection molding machine, the molten plastic is injected into the mold cavity, and the cooling in the cavity is finalized, and then the upper and lower molds are separated, through the ejecting system will be products from the mold cavity out of the mold, and finally the mold is closed for the next injection molding, the whole injection molding process is carried out in a cycle.
3. General classification of moulds: it can be divided into plastic moulds and non-plastic moulds:
(1) non plastic mold: casting mold, forging mold, stamping die, die casting mold, etc.
A. Casting mold - faucet, pig iron platform
B. Forging die - car body
C. Stamping die - computer panel
D. Die casting mold -- superalloy, cylinder body
(2) According to the production process and the production of different products, the plastic mold is divided into:
A. Injection moulds -- TV sets, keyboard buttons (most commonly used)
B. Blow mold - beverage bottle
C. Compression molding mold - bakelite switch, scientific porcelain dishes
D. Transfer mold - integrated circuit products
E. Extrusion mold - glue tube, plastic bag
F. Thermal molding mold - transparent molding packaging shell
G. Rotating molding mold - soft glue doll toy
◆ Injection molding is the most widely used method in plastic processing. This method is suitable for all thermoplastic plastics and part of thermosetting plastics, and the number of plastic products produced is beyond other molding methods. As one of the main tools of injection molding processing, the injection mold has a high level in quality precision, manufacturing cycle and production efficiency in the process of injection molding. Direct impact on product quality, output, cost and product update, but also determines the response ability and speed of enterprises in the market competition.
◆ Injection mold is composed of a number of steel plates with various parts, basically divided into:
A Forming device (die, punch)
B Positioning device (guide post, guide sleeve)
C Fixed device (I-plate, code pit)
D Cooling system (water hole)
E Constant temperature system (heating tube, hairline)
F Channel system (jogger hole, channel slot, channel hole)
G ejection system (thimble, ejector)
5, according to the different type of gating system can be divided into three types of molds:
(1) Large nozzle mold: the runner and gate are on the parting line and demoulded together with the product when the mold is opened. The design is the simplest, it is easy to process and the cost is low, so more people use large nozzle system to operate.
(2) fine nozzle mold: the runner and gate are not on the parting line, and they are generally directly on the product, so it is necessary to design one more group of outlet parting line. The design is more complex and the processing is more difficult. Generally, the fine nozzle system is selected according to the product requirements.
(3) Hot runner mould: Such mold structure to be about equal to the fine shuikou, the biggest difference is that the flow is in one or more have temperature and heat flow but heat pumping mouth, no cold feeding demoulding, runner and gate directly on the product, so the port don't need mold release, also known as no runner system, this system can save raw materials, applicable to the raw material is more expensive, high requirement of products, design and processing difficulties, The mould cost is higher.
Hot runner system, also known as hot runner system, is mainly composed of hot gate sleeve, hot runner plate, temperature control electric box. Our common hot runner system has two forms: single point hot gate and multi-point hot gate. Single point hot sprue is a single hot sprue sleeve directly injected the molten plastic into the cavity, it is suitable for single cavity single sprue plastic mold; The multi-point hot gate is to branch the molten material into the separate heat gate sleeve through the hot gate plate and then enter the mold cavity. It is suitable for single-cavity multi-point feeding or multi-cavity mold.
◆ Advantages of hot runner system
(1) No outlet material, no need for post-processing, so that the whole molding process is fully automated, save working time, improve work efficiency.
(2) Small pressure loss. The temperature of the hot runner is equal to that of the injector of the injection molding machine, which avoids the surface condensation of the raw material in the runner and reduces the loss of the injection pressure.
(3) the repeated use of nozzle material will degrade the plastic performance, and the use of hot runner system without nozzle material, can reduce the loss of raw materials, thereby reducing the cost of products. In the cavity, the temperature and pressure are uniform, the plastic parts stress is small, the density is uniform, under the smaller injection pressure, the shorter molding time, the injection molding system is better than the general product. For transparent parts, thin parts, large plastic parts or high-demand plastic parts can show its advantages, and can be used to produce larger products with smaller models.
(4) the hot nozzle adopts the standardized, serialized design, equipped with a variety of optional nozzle head, good interchangeability. The electric heating ring with unique design and processing can achieve uniform heating temperature and long service life. Hot runner system is equipped with hot runner plate, temperature controller, etc., exquisite design, variety, easy to use, stable and reliable quality.
◆ The deficiency of the application of hot runner system
(1) The closure height of the overall mold is increased, and the overall height of the mold is increased due to the addition of hot runner plate, etc.
(2) the heat radiation is difficult to control, the biggest problem of the hot runner is the heat loss of the runner, which is a major issue that needs to be solved.
(3) there is thermal expansion, thermal expansion and cold contraction is our design to consider the problem.
(4) The cost of mold manufacturing increases, and the price of standard parts of hot runner system is higher, which affects the popularity of hot runner mold.
Plastic blow molding information