Mold: Various molds and objects used in industrial production for injection molding, blow molding, extrusion, die-casting or forging, shaping, exercising, stamping, stretching and other methods to obtain the required goods.

In short, a mold is something used to shape objects, which is composed of various parts, and different molds are composed of different parts. It primarily completes the processing of the shape of the object by modifying the physical condition of the formed data.

According to the different materials formed, molds can be divided into metal molds and non-metal molds. Metal molds are divided into casting molds (non-ferrous metal die-casting, steel casting), and casting molds, etc; Non metallic molds are also divided into plastic molds and inorganic non-metallic molds. According to the different information of the molds themselves, molds can be divided into sand molds, metal molds, vacuum molds, white wax molds, and so on. During this time, with the rapid opening of polymer plastics, plastic molds are closely related to our lives. Plastic molds can usually be divided into injection molding molds, extrusion molding molds, gas assisted molding molds, and so on.

Typical types of molds

Two plate mold, also known as single parting surface mold, is a simple type of injection mold. It divides the entire mold into two parts with the parting surface as the interface: the moving mold and the fixed mold. Some cavities are in the moving mold, while others are in the fixed mold. Dry channel in fixed mold; The diversion channel is set on the parting surface. After the mold is opened, the product and flow channel are left in the moving mold, and some of the moving molds are equipped with an ejection system. （2）The three plate mold or fine water nozzle mold has two parting surfaces that divide the mold into three parts. Compared to the two plates, it adds a sprue plate, which is suitable for situations where sprue marks are prohibited near the product. This type of mold uses a sprue, so it is called a fine water nozzle mold. The design of this type of mold is correspondingly more complicated. Activate the power by screwing or pulling a plate with a mountain.

Classified by molding method

Injection molding is the process of first adding plastic into the heating cylinder of an injection machine, where the plastic is heated and melted. With the push of the injection machine's screw or plunger, it enters the mold cavity through the nozzle and mold casting system, and hardens and shapes into injection molded products due to physical and chemical reactions. Injection molding consists of a cyclic process involving injection, pressure holding (cooling), and demolding of plastic parts, thus exhibiting periodic characteristics. The molding cycle of thermoplastic injection molding is short, the production power is high, the wear of the melt on the mold is small, and it can form large quantities of plastic parts with messy shapes, clear external drawings and symbols, and high dimensional accuracy; However, for plastic parts with significant changes in wall thickness, it is difficult to prevent molding defects. The anisotropy of plastic parts is also one of the quality issues, and all possible methods should be used to minimize it as much as possible. （2）Tightening molding, commonly known as restricted molding, is one of the methods for early forming plastic parts. Tightening molding is the process of directly introducing plastic into an open mold cavity at a certain temperature, then closing the mold and melting the plastic into an active state under the action of heat and pressure. Due to physical and chemical processes, plastic hardens into a shape and scale that remains unchanged at room temperature. Tightening molding is primarily used for molding thermosetting plastics, such as phenolic molding powder, urea formaldehyde and melamine formaldehyde molding powder, glass fiber reinforced phenolic plastics, epoxy resinsDAPMolding plastics such as resin, silicone resin, polyimide, etc. can also be used to shape and process unsaturated polyester pellets（DMC）Sheet molding compound（SMC）Prefabricated full mold plastic（BMC）Wait. Usually, according to the cooperation plan of the upper and lower molds of the compression film, the compression molds are divided into three categories: overflow type, non overflow type, and semi overflow type. （3）Extrusion molding is a method of shaping plastic in a viscous flow state into a continuous profile of the desired cross-sectional shape at a lower temperature through a die with a specific cross-sectional shape under high temperature and pressure. The production process of extrusion molding involves preparing molding materials, extruding shapes, cooling and shaping, pulling and blocking, and disposing of extruded products (quenching or heat treatment). During the extrusion molding process, pay attention to adjusting the temperature, screw speed, traction speed, and other technical parameters of each heating section of the extruder barrel and the die head in order to obtain qualified extruded profiles. Special attention should be paid to adjusting the extrusion rate of polymer melt from the die of the machine head. Because when the extrusion rate of molten material is low, the extruded material has a lubricating surface and a uniform cross-sectional shape; But when the extrusion rate of the molten material reaches a certain limit, the surface of the extruded material will become rough, lose its luster, and exhibit appearances such as shark skin, orange peel patterns, and distorted shapes.

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