Mold in the production of silicone products, the first issue to consider is the choice of mold materials. According to product quality, quantity, and structure to determine the selection of the mold. Mold material selection is the entire mold making process is very important link. Mold material selection need to meet three requirements: First of all, die met wear resistance, toughness, etc. needs; Secondly, the mold meet the technical requirements; again, mold should meet the requirements of economic fitness.
(A) of the mold required to meet the working conditions
1, wear resistance
Blank in the mold cavity in the plastic deformation, the flow along the cavity surface, they both slide to the cavity surface and a sharp friction between billet and thus prone to mold because of wear and failure. Therefore, the wear resistance of material is die most fundamental and important one performance.
Hardness of the main factors affecting the wear resistance. In general, the higher the hardness of mold parts, the smaller the wear, abrasion resistance, the better. In addition, the wear resistance of carbide with material type, quantity, shape, size and distribution of the.
2, strength and toughness
Mold most appalling working conditions, often bear some of the larger impact load, leading to brittle fracture. To prevent mold parts at work, suddenly brittle fracture, die to have high strength and toughness. Mold depends on the material toughness of the carbon content, grain size and organization of the state.
3, fatigue fracture properties
Die working process, in the long-term effect of cyclic stress often leads to fatigue fracture. The form of a small number of energy impact fatigue fracture, fatigue fracture of the contact fatigue fracture tensile and bending fatigue fracture.
Die of fatigue fracture properties are dependent on their strength, toughness, hardness, and material content of inclusions.
4, high temperature performance
When the mold temperature is high, the hardness and strength will decrease, leading to early wear or mold plastic deformation and failure. Therefore, the mold material should have high temper resistance, to ensure that die in the operating temperature, high hardness and strength.
5, anti-fatigue properties of hot and cold
Some die in the course of their work in the repeated heating and cooling of the state, so that the cavity surface tension, pressure changes the role of stress, causing surface cracking and spalling, increased friction, obstruction of plastic deformation, reduced dimensional accuracy, resulting in Die failure. Thermal fatigue is a hot die one of the main forms of failure to help this type of mold should have a high resistance to thermal fatigue.
6, corrosion resistance
Some molds, such as plastic mold at work, because there is plastic in the chlorine, fluorine and other elements, heated decomposition precipitation HCI, HF and other strong corrosive gases, mold cavity surface erosion, increase its surface roughness, increased wear failure.
(B) of the mold meet the technical performance requirements
Mold manufacturing generally go through forging, machining, heat treatment, several working procedure. To ensure the quality of mold manufacturing, lower production costs, the material should have good malleability, machinability, hardenability, hardenability and can be grinding sex; should have little oxidation, decarbonization and quenching sensitivity deformation cracking tendency.
1, malleable
Hot deformation resistance with the lower, plastic good, wide range of forging temperature, forging crack network carbide precipitation of cold cracking and a low propensity.
2 Process of
Ball annealing temperature range, annealing hardness range of low and volatile small, the ball high.
3 Machinability
Cutting large, tool wear is low, low surface roughness.
4, oxidation, decarbonization sensitivity
Antioxidant pregnant when heated to high temperatures can be good, decarbonization, slow is not sensitive to the heating medium, resulting in pitting tendency of small.
5, hardenability
After quenching with a uniform and high surface hardness.
6 hardenability
After quenching to obtain a deeper hardened layer can be used to ease the quenching medium hardening.
7, quenching distortion cracking tendency
Quenched and small volume change, shape warping, distortion slight tendency to lower abnormal deformation. Low sensitivity of conventional quench cracking on quenching temperature and is not sensitive to the shape of the workpiece.
8, may be grinding of
Wheel relative loss, no amount of grinding burn limit large, the quality of the grinding wheel and the cooling conditions are not sensitive, less prone to injuries grinding grinding cracks.
(C) of the mold to meet the economic requirements
To die in the selection, we must consider the economic nature of this principle, as much as possible to reduce manufacturing costs. Therefore, to meet the performance of the premise, first, a lower price, and can use carbon steel do not need, can use domestic materials do not need to import materials.
In addition, selection should also consider the market's production and supply of selected steel should be minimal and concentrated, easy to buy.
Selection of knowledge about the mold can make mold of the advantages of better play. To open a better and more high-quality molds |
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