플라스틱 사출성형(Injection Molding)

◆ Plastic Injection ◎ Injection Molding Steps 1) Plastication: Melting the raw material into a molten state. 2) Mold Closing: Closing the mold. 3) Filling: Injecting the raw material into the mold. 4) Packing: Maintaining pressure to control shrinkage. 5) Cooling: Solidifying through coolant circulation. 6) Mold Opening & Ejection: Opening the mold and removing the molded plastic. Injection molding, which creates products using a mold, has its origins in casting, which involves pouring molten metal into a mold to create a product. Casting is a method of manufacturing by pouring molten material into a mold. When plastic is melted, it's called injection molding, and when metal is melted, it's called die casting. ※ Pressing is the process of applying pressure to a metal plate to create various shapes. Extrusion is a continuous production method of producing uniform, long products by forcing material, either heated or unheated, through a die with a specific hole in a container. Precision machining involves precisely cutting the shape using machines such as CNC milling machines. Injection molding is the most common method used in mass production. It involves forcing plastic into a mold under high pressure to form the desired shape. Almost all plastic products commonly seen around us are made using injection molding. ◎ Injection Molding Unit This unit melts the plastic material and injects it into a mold. Hopper, Barrel, and Reciprocating Screw It consists of three components: ◎ Pellet, a plastic molding material ○ An electric heater operates around the barrel (the tube that injects the material into the mold). ※ Masterbatch In the process of mixing additives into rubber or plastic raw materials, additives are mixed and kneaded at a concentration higher than the prescribed concentration. By mixing them into rubber or plastic raw materials, it allows for precise dosing of each additive, promotes dispersion, and prevents splattering during processing. ※ Runner The path through which the molten plastic flows to the mold cavity. The runner's ridges should be thicker than the product's wall thickness. ※ Cavity: The space in the mold where the mold is formed. Core: The protruding portion of the mold that forms the inner surface of the molded part. i.e., the mold part used to form plungers and undercuts. ※ ABS (Acrylonitrile Butadiene Styrene) Excellent tensile strength and impact strength Excellent mechanical properties (high hardness, high strength) Excellent painting and plating performance ※ PP (Poly Propylene) Low specific gravity, low price, and high flexural strength Flexible as a crystalline resin Poor dimensional stability, paintability, and adhesive performance ※ Composite Materials that enhance functionality (physical properties, strength) by adding reinforcing materials to plastic raw materials Glass fiber and talc are most commonly used ===================================== ◎ Filming assistance and interview: Park Kyung-hoon, CEO of Bukwang Plastics