Basic knowledge of mold

- Jun 28, 2019-

2, the general definition of mold
In industrial production, parts or products of the desired shape of metal or non-metallic materials are produced by pressure using various pressure machines and special tools mounted on pressure machines. This special tool is collectively referred to as a mold.
3, injection process description
Mould is a tool for the production of plastic products. It consists of several sets of parts. This combination has a molded cavity. During injection molding, the mold is clamped into the injection molding machine. The molten plastic is injected into the molding cavity and cooled in the cavity. Then the upper and lower molds are separated. The product is topped out of the mold through the top exit system. The mold is closed again. For the next injection molding, The entire injection process is circular.
4, the general classification of molds
Can be divided into plastic molds and non-plastic molds:
(1) Non-plastic molds have: casting molds, forging molds, stamping molds, die-casting molds, etc..
A. Casting molds-faucets, pig iron platforms
B. Forging-car body
C. Stamping die-computer panel
D. Die-casting die-superalloy, cylinder body
(2) Plastic molds are divided into:
A. Injection moulds -- television case, keyboard buttons(most commonly used)
B. Blowing moulds-drinking bottles
C. Compressed moulds-electric wood switches, scientific porcelain dishes
D. Transfer moulds-integrated circuit products
E. Extrusion moulds-rubber pipes, plastic bags
F. Thermoforming die-transparent forming packaging case
G. Rotation moulds-soft plastic doll toys
Injection molding is the most commonly used method in plastic processing. The method is suitable for all thermoplastic plastics and some thermosetting plastics. The large number of plastic products produced is beyond the reach of other molding methods and is used as one of the main tools for injection molding. The level of quality accuracy, manufacturing cycle and production efficiency in injection molding process directly affects product quality, output, cost and product renewal, and also determines the responsiveness and speed of enterprises in market competition.
Our products are all injection molding.
The injection mold is composed of several steel plates and various parts. It is basically divided into:
A molding device(concave, convex)
B positioning device(guide column, guide sleeve)
C fixing device(workplate, code mold pit)
D Cooling system(water port)
E Heating system(heating pipe, firing line)
F Stream system(pump hole, runner slot, runner hole)
G top out system(thimble, thimble)
5, depending on the pouring system type can be divided into three types:
(1) Dashuikou mold: The flow channel and the gate are on the sub-mold line, and the product is demoulded together when the mold is opened. The design is the simplest, easy to process, and the cost is low. Therefore, more people use the Dashuikou system to operate.
(2) Fine water port mold: The flow channel and the gate are not on the division line and are generally directly on the product. Therefore, a group of water port die lines must be designed. The design is more complex and the processing is more difficult. Generally, depending on the product requirements. Choose a fine water port system.
(3) Heat channel dies: The structure of such dies is roughly the same as that of fine water outlets. The biggest difference is that the flow channel is in one or more heated hot channel plates and hot jaws, and there is no cold material demoulding, and the flow channel and gate are directly on the product. Therefore, the flow channel does not need to be demoulded. This system is also called an anhydrous mouth system. It can save raw materials and is suitable for situations where raw materials are more expensive and products require higher requirements. It is difficult to design and process, and the mold cost is higher.
The so-called 2 plate mold generally refers to the large water port system mold, 3 plate mold generally refers to the fine water port system mold. 3 board die can not simply think of more than 2 board die one plate, according to the product shape and mold design needs, the mold can have more than 3 board knot
The hot channel system, also known as the hot channel system, mainly consists of a hot gate cover, a hot channel board, and a temperature controlled electric box. Our common hot channel system has two forms: single point hot gate and multiple point hot gate. The single point heat gate is to directly insert the molten plastic into the cavity with a single heat gate sleeve. It is suitable for a single cavity plastic mold; The multi-point heat gate is to branch the melt material into each heat separation gate sleeve and enter the cavity. It is suitable for single-cavity multi-point feed or multi-cavity mold.
Advantages of the hot runner system
(1) No water mouth material, no need for post-processing, so that the entire molding process is fully automated, saving work time and improving work efficiency.
(2) Low pressure loss. The temperature of the hot casting channel is equal to that of the injection nozzle of the injection molding machine, which avoids the condensation of the raw material on the surface of the casting channel, and the injection pressure loss is small.
(3) Reuse of the water mouth material will degrade the properties of the plastic, and the use of the hot channel system without the water mouth material can reduce the loss of raw materials and thus reduce the cost of the product. In the cavity, the temperature and pressure are uniform, the plastic stress is small, and the density is uniform. Under the smaller injection pressure, the shorter molding time, the injection molding system is better than the general injection molding system. For transparent parts, thin parts, large plastic parts or high-demand plastic parts can show their advantages, and can use smaller models to produce larger products.
(4) The thermal nozzle adopts a standardized and serialized design and is equipped with a variety of alternative nozzles, which are interchangeable. The electric heating ring specially designed and processed can achieve uniform heating temperature and long service life. The hot channel system is equipped with hot channel plates, thermostats, etc.. The design is exquisite, diverse, easy to use, and the quality is stable and reliable.
Deficiencies in the application of hot runner system
(1) The height of the overall mold closure is increased, and the overall height of the mold is increased due to the installation of hot casting plates.
(2) Thermal radiation is difficult to control. The biggest problem of the hot channel is the heat loss of the channel. It is a major problem that needs to be solved.
(3) The existence of thermal expansion, thermal expansion and cooling is a problem that we should consider when designing.
(4) Increased die manufacturing costs, high price of standard parts of the hot casting system, affecting the popularity of hot casting dies.
The companies that provide hot flow standard parts are: DME, HASCO, HUSKY, EOC, FULLY, MASTER-TIP, INCOE and others.
When I make the mold, the hot channel system generally uses the brand designated by the customer. If the customer does not specify the brand, I can select the more common brand, such as DME, HASCO, etc..