Explanation of terms of material technology

Thermit welding: during welding, the ends of the two workpieces to be welded are fixed in the mold in advance, and then the mixture of aluminum powder and iron oxide powder (called thermite) is heated in the crucible to make it undergo reduction exothermic reaction to become liquid metal (iron) and slag (mainly Al2O3) and injected into the mold. The liquid metal flows into the gap of the joint to form the weld metal, and the slag floats on the surface.

Sand mold casting: a casting method for generating castings in sand mold. Basic raw materials: casting sand and molding sand binder. The mold is composed of outer sand mold and core. In order to improve the surface quality of castings, a layer of coating is often applied on the surface of sand mold and core. The main components of the coating are powder materials and binders with high fire resistance and good chemical stability at high temperature.

Injection molding: after plastic is plasticized in the heating barrel of the injection molding machine, it is injected into the mold cavity of the closed mold by the plunger or reciprocating screw to form the plastic processing method of the product. This method can process products with complex shape, accurate size or with inserts, and has high production efficiency.

Yield strength: the external force greater than this limit will permanently invalidate the parts and cannot be recovered. This pressure is called yield strength.

Annealing: a metal heat treatment process in which metal components are heated above or below the critical point for a certain period of time, and then cooled slowly, so as to obtain near equilibrium microstructure and properties.

Tempering: the heat treatment process of heating the quenched steel below AC1 and cooling it after heat preservation.

Q195: it is a kind of carbon structural steel. Yield strength 195mpa.

45: high quality carbon structural steel with average carbon content of 0.45%

9CrSi: alloy tool steel with carbon content of 0.9% and chromium and silicon content of less than 15%

Plywood: it is a three-layer or multi-layer plate-like material formed by turning wood sections into veneers or planing wood into thin wood, and then gluing with adhesive. Usually, odd layers of veneers are used, and the fiber directions of adjacent veneers are glued perpendicular to each other.

Fiberboard: an artificial board made from wood processing waste or plant fiber through crushing, soaking, pulping, molding, drying and hot pressing.

Investment casting: also known as wax loss method. It usually refers to the casting scheme that the fusible material is made into a pattern, the surface of the pattern is coated with several layers of refractory materials to make a mold shell, and then the pattern is melted out of the mold shell, so as to obtain a mold without parting surface, which can be filled with sand after high-temperature roasting.

Pressure casting: in essence, it is a method to make liquid or semi-liquid metal fill the die-casting mold (die-casting mold) cavity at a high speed under the action of high pressure, and form and solidify under pressure to obtain castings.

Metal mold casting: also known as hard mold casting, it is a casting method of pouring liquid metal into metal mold to obtain castings. Features: the mold is generally made of metal, and the weight and shape of the casting will be limited.

Spot welding: the weldment is welded at individual points on the contact surface of the joint. Spot welding requires good plasticity of metal.

Carbonization flame: in the combustion process, the combustible gas acetylene is excessive, and there is black smoke in the flame. Free carbon will penetrate into the molten pool and increase the carbon content of the welding hole. If too much hydrogen enters the molten pool, pores and cracks will occur.

Neutral flame: in the combustion process, the supply of oxygen is exactly equal to the oxygen demand of complete combustion of the gas. There is neither excess oxygen nor the flame of reducing gases such as carbon monoxide generated by hypoxia in the products after fuel.

Demoulding slope: that is, the draft slope, which is designed on both sides of the mold chamber for the convenience of mold out. The orientation of demoulding slope shall be determined according to the internal and external dimensions of plastic parts.

Stiffener: in the process of structural design, the overhang surface of the structure may be too large or the span may be too large. In such a case, the load that the connecting surface of the structure itself can bear is limited, then a stiffener plate, commonly known as stiffener (Jin reinforcement in Engineering), is added on the common vertical plane of the two structures to increase the strength of the joint surface.

Tenon combination: the material is designed as concave convex fastened with each other. There is no need to connect with nails, glue and so on, just knock.

Glue combination: it is a common combination line of wood products. It is mainly used for the splicing of solid wood plates and the gluing of tenons and mortise holes. It is characterized by simple manufacture, firm structure and beautiful appearance. The product form is not limited by manual technology.