Mold core, as the name implies, refers to the key operation of the central part of the die precision parts. Die core general structure is extremely complex, processing difficulty is very large, the cost is very high, often manufacturing labor expenditure is much more than the material itself. The choice of core material is also directly related to the cost and service life of the mold.
1. Change the plastic melt from spiral motion to linear motion;
2. The compression ratio is formed to produce the necessary molding pressure to make the extruded plastic melt compact;
3. narrow channel to enhance shear, plastic get further plasticization;
4. Make the material layer thinner, which is conducive to further uniform plasticizing;
5. narrow channel to enhance shear, is the molecular chain orientation, increase the product strength.
The choice of die core material is directly related to the life of the die and the price of the die. In terms of products, product demand for small, choose a good mold core material, mold cost is increased, for the company increases the cost, it is a waste, product demand is big, poor choice of mold core material, cannot meet the production demand, mold is discarded, need to open mold, production efficiency, also increased the mold cost. In order to choose the core material reasonably, it is necessary to understand the characteristics of the core material and the core material commonly used in the mold.
Core materials: P20, 738, 738H, 718, 718H, NAK80, 2316, 2316A, S136, etc.
Properties of materials
1) P20: generally applicable to the requirements of high hardness, high toughness and wear resistance of the plastic mold, after nitrogen can improve the life of the mold, applicable to PS, PE, PP, ABS and other non-added fire-retardant thermoplastics, in the mold is a common mold material, and its price is also relatively low.
2) 738: compared with P20, all kinds of performance have been improved, 738H and 738 better than the effect, and correspondingly increased the life of the mold.
3) NAK80: EDM and polishing performance are relatively good, generally used in plastic products with higher transparency requirements.
4) 2316: suitable for the mold of high acid plastic, with high finish and high acid resistance, generally used in the mold of plastic material forming PVC.
5) 2344: generally used in the plastic hard mold, its mold life can reach 1 million times, but due to the high cost of the mold, it is suitable for the plastic products with large product output. The same is true of hard mold materials such as 8407 and SKD11.
Core processing equipment: due to the complexity of the core and the difficulty of the process, the general core processing equipment is very much.
Mold core structure of mobile phone: CNC precision machining center, computer machining center, MC machining center, walking wire, wire cutting machine, grinding machine, optical grinding machine, computer gong-bed, surface grinding machine, etc.
Mold core accuracy is generally required to be ±0.005mm
The role of the die core
Manufacturing mold terminology, that is, the parts that constitute the product space is called the forming parts (that is, the mold as a whole), the forming products of the inner surface of the (mold) parts is called the Core, also known as the sub – or post-mold. From the appearance of the product mold, the raised part is the mold core, and the concave part is the Cavity. The mold core and Cavity appear in pairs, and the Cavity of the mold is closed to the mold core, and the space formed is the mold shape.
1. Die and die set die also known as female die. The shape of the die is usually round or rectangular, and the fewer the combined parts, the stronger the use. But for many parts and cannot take the concave die as a whole, often in order to facilitate processing, it made of combination. Die sleeve is a component used for clamping die or punch forming parts.
2. Punch (also known as the male) is the parts of the inner surface molding. It is often composed of the whole or several parts of the Mosaic structure, its role is to transfer the pressure of the press to the plastic, plastic parts compact.
3. Core and insert core is to make plastic parts forming through hole or blind hole parts, the core has fixed and movable two.
4. Thread core and threaded ring
The thread core is designed to form a threaded hole in plastic parts and can also be used for joining or fixing threaded and spring-threaded inserts into parts.
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