(1) The mould meets the requirements of working conditions
When the blank is plastically deformed in the mould cavity, it flows and slides along the surface of the cavity, causing severe friction between the surface of the cavity and the blank, resulting in the failure of the mould due to wear. Therefore, the wear resistance of the material is one of the most basic and important properties of the mould.
Hardness is the main factor affecting wear resistance. In general, the higher the hardness of the mould parts, the smaller the amount of wear and the better the wear resistance. In addition, the wear resistance is also related to the type, number, form, size and distribution of carbides in the material.
Strong and tough
Most of the working conditions of the mould are very bad, and some often bear large impact loads, which leads to brittle fracture. In order to prevent the mould parts from being brittlely broken during work, the mould should have high strength and toughness.
The toughness of the mould mainly depends on the carbon content, grain size and microstructure of the material.
Fatigue fracture performance
In the process of mould work, under the long-term effect of cyclic stress, it often leads to fatigue fracture. Its forms are low energy multiple impact fatigue fracture, tensile fatigue fracture contact fatigue fracture and bending fatigue fracture.
The fatigue fracture performance of the mould mainly depends on its strength, toughness, hardness, and the content of inclusions in the material.
High temperature performance
When the working temperature of the mould is higher, the hardness and strength will decrease, resulting in early wear or plastic deformation of the mould and failure. Therefore, the mould material should have high stability against tempering to ensure that the mould has high hardness and strength at the working temperature.
Cold and heat fatigue resistance
Some moulds are in the state of repeated heating and cooling during the work process, which causes the surface of the cavity to be pulled and the stress of the pressure changes, causing surface cracking and flaking, increasing friction, hindering plastic deformation, and reducing dimensional accuracy, resulting in mould failure. Hot and cold fatigue is one of the main forms of hot work die failure. This type of mould should have high resistance to cold and hot fatigue.
When some moulds such as plastic moulds work, due to the presence of chlorine, fluorine and other elements in the plastic, after heating, the strong corrosive gases such as HCI and HF are decomposed, eroding the surface of the mould cavity, increasing its surface roughness, and exacerbating wear failure.
(2) The mould meets the process performance requirements
The manufacture of the mould generally goes through several processes such as forging, cutting, and heat treatment. In order to ensure the manufacturing quality of the mould and reduce production costs, the material should have good forgeability, cutting workability, hardenability, hardenability and grindability; it should also have small oxidation, decarburization sensitivity and quench Deformation and cracking tendency.
It has low resistance to hot forging deformation, good plasticity, wide forging temperature range, low forging cracking and low tendency to precipitate network carbide.
The spheroidizing annealing temperature range is wide, the annealing hardness is low and the fluctuation range is small, and the spheroidizing rate is high.
Large amount of cutting, low tool loss and low surface roughness.
Sensitivity to oxidation and decarburization
Antioxidation is good when heated at high temperature, the decarburization speed is slow, it is not sensitive to the heating medium, and the tendency to produce pitting is small.
After quenching, it has uniform and high surface hardness.
After quenching, a deeper hardened layer can be obtained, which can be hardened by using a mild quenching medium.
Cracking tendency of quenching deformation
Conventional quenching has small volume changes, slight warpage and distortion, and low tendency to abnormal deformation. Conventional quenching has low cracking sensitivity and is insensitive to quenching temperature and workpiece shape.
The relative wear of the grinding wheel is small, and the maximum amount of grinding without burns is large. It is not sensitive to the quality of the grinding wheel and the cooling conditions, and it is not easy to cause scratches and grinding cracks.
(3) mould meets economic requirements
In the selection of materials for moulds, the principle of economy must be considered to reduce manufacturing costs as much as possible. Therefore, on the premise of satisfying the use performance, first of all, choose the lower price, carbon steel can be used without alloy steel, domestic materials can be used without imported materials.
In addition, the production and supply of the market should also be considered when selecting materials. The steel types selected should be as few and concentrated as possible and easy to purchase.
Yuhuan Shengjiu Mould Co., Ltd. is a professional China manufacturer and supplier of Medical Mould . The main production and supply: medical mould products such as syringe moulds, safety needle moulds, oxygen mask moulds, needleless injection takeovers, vaginal expander moulds and so on. And provide customers with a complete mould configuration program to help and improve the production of disposable medical equipment. According to the requirements of the market and customers, Shengjiu has developed a new type of medical mould with a full hot runner system, and developed a variety of new scientific medical equipment for customers. Welcome to consult and order: https://www.medicalmould.net/