As a product structure or mechanical engineer, it is necessary to master basic understanding of injection molds. It can help you better develop products. Details are as follows:
Tag: hot runner mold
When did the earliest molds appear? Facts show that humans began to use molds as early as 5,000 to 7,000 years ago. Without use of molds, it is unimaginable to produce large-scale bronze works such as large standing bronze figure, standing figure of a naked and crowned priest, and Simuwu Dafang Ding.
Inner outer shell of door component is divided into two plastic parts, see 3D diagram. Maximum outer dimension of product is 266.26.0 mm * 152.93 mm; average glue thickness of plastic parts is 3.00 mm, plastic parts material is FPP ATX799HF, and shrinkage rate is 1.009. Technical requirements for plastic parts are that there must be no defects such as peaks, underfilling, flow lines, pores, warping deformation, silver streaks, cold materials, jet lines, etc. and they must comply with ROSH environmental requirements.
Scanner base products are shown in Figure 1. Maximum dimensions of product are 371.37 mm * 285.93 mm * 65.83 mm; average thickness of plastic part is 2.50 mm, material of plastic part is PS HI, shrinkage rate is 1.005, and weight of plastic part is 391.30 grams. Technical requirements for plastic parts are that there should be no defects such as peaking, underfilled injection molding, flow lines, pores, warping deformation, silver streaks, cold material, and jetting lines, and meet ROSH environmental protection requirements.
HRC/HB approximate conversion tips Hardness is higher than 20HRC, 1HRC≈10HB, Hardness is lower than 20HRC, 1HRC≈11.5HB. Remarks: For cutting processing, 1HRC≈10HB can basically be converted uniformly (hardness of workpiece material has a fluctuation range)
"Magic" of injection molds There is a type of injection mold, called a multi-cavity mold, which occupies half of the entire plastic product field. Demand for these plastic products is very large, some in tens of millions, some in hundreds of millions. For example: plastic hangers, plastic cheese sticks, plastic cutlery, mask buckles and so on. Even nucleic acid detection kits and nucleic acid detection sampling sticks that we often come into contact with now are in tens of billions. Under same production conditions, under premise of maximizing quality of plastic products, how to reduce production cost of these huge quantities of plastic products is dream of plastic engineers, mold designers and entrepreneurs in injection molding industry, but reality is difficult. Because in production process of these plastic products, there are many constraints. I call it "magic". Let's take a look at what these "magic" are all about.
POM (also known as Saigang, Trane). It is obtained by polymerization of formaldehyde as raw materials. POM-H (polyoxymethylene homopolymer) and POM-K (polyoxymethylene copolymer) are thermoplastic engineering plastics with high density and high crystallinity. Has good physical, mechanical and chemical properties, especially excellent friction resistance. POM is a crystalline plastic with obvious melting point. Once it reaches melting point, melt viscosity drops rapidly. When temperature exceeds a certain limit or melt is heated for too long, it will cause decomposition. Copper is a catalyst for POM degradation, copper or copper materials should be avoided in parts in contact with POM melt.
According to different types of gating system, plastic molds can be divided into three categories: (1) Large nozzle mold Runner and gate are on parting line and are demolded together with product when mold is opened. Design is the simplest, easy to process, and low cost, so more people use large nozzle system to work. Plastic mold structure is divided into two parts: movable mold and fixed mold. Movable part of injection machine is movable mold (mostly ejection side), injection end of injection machine is generally inactive and called fixed mold. Because fixed mold part of large nozzle mold is generally composed of two steel plates, this type of structural mold is also called "two-plate mold". Two-plate mold is the simplest structure in large nozzle mold.
【Abstract】Structural characteristics of transparent plastic cups for aviation are analyzed, mold structure, design characteristics, material selection and demoulding methods of thin-walled plastic parts are introduced, and application of Bernoulli effect in compressed air ejection of thin-walled parts is introduced. It has been verified by manufacturer that mold structure design is reasonable and fully meets structural and technological thin-walled cup, which can be used for reference by engineers and technicians engaged in design and manufacture of injection molds.
Dimensional instability means that under same injection molding machine and molding process conditions, size of plastic part changes between each batch of molded products or between each cavity molded product produced by each mold.
Gud Mould 