Category: Manufacturing Technology knowledge

NDT refers to the defect that does not damage the surface or interior of the casting, or called NDT. There are many NDT test methods, and the following four methods are widely used in production: magnetic particle flaw detection, ultrasonic flaw detection, radiographic flaw detection, and liquid penetrant flaw detection. 1. Magnetic particle flaw detection: ferromagnetic materials such as iron and steel will be subject to this if they pass through a large current or are placed in a magnetic field. For defects on the surface, such as cracks and inclusions, the magnetic line of force is not easy to…

The surface heat treatment is divided into two categories, one is surface quenching and tempering heat treatment, and the other is chemical heat treatment. The hardness test methods are as follows: 1. Surface quenching and tempering heat treatment The surface quenching and tempering heat treatment is usually conducted by induction heating or flame heating. The main technical parameters are surface hardness, local hardness and effective hardened layer depth. The Vickers hardness tester, Rockwell or Superficial Rockwell hardness tester can be used for hardness testing. The selection of test force (scale) is related to the effective hardened case depth and workpiece…

1. Purpose: to standardize the production process, operation contents and methods 2. Scope: applicable to pre-treatment in plastic spraying workshop. 3. Process flow: Degreasing (alkaline) → water washing → rust removal → water washing → neutralization → surface conditioning → phosphating → water washing → post phosphating treatment (spraying) 4. Operation content and key control points: 4.1 Workpiece framing: handle with care to prevent deformation of workpieces. The height shall not exceed the scope of solution blistering (the effect of oil removal and phosphating is better than that of regular oil removal and phosphating when products are placed in a…

The surface performance of die parts is very important to the working performance and service life, such as wear resistance, corrosion resistance, friction coefficient, fatigue performance, etc. It is very limited and uneconomical to rely solely on the improvement and enhancement of the matrix materials. However, through the surface treatment technology, we can get twice the result with half the effort. Therefore, the mold surface treatment technology has been developed rapidly. This technology is a system engineering that changes the shape, chemical composition, structure and stress state of the die surface through surface coating, surface modification or composite treatment technology…

Steel for heavy forgings - forging process Large ingots are required for smelting and forging large forgings. The single weight of large ingots ranges from 30 to several hundred tons. The larger the ingot is, the more serious the metallurgical defects such as segregation are. Therefore, the smelting requirements of steel for large forgings are very strict. In order to ensure the casting of extra large steel ingots, it is generally necessary to use more than two smelting furnaces for casting, so it is not necessary to increase the capacity of a single furnace and reduce the erosion of refractory…

In recent years, due to the requirements of environmental protection, the small cupola of most foundry enterprises has been replaced by the small medium frequency induction furnace. As the cupola uses coke and other fuels, metallurgical reaction occurs in the smelting process, while the electric furnace smelting is mainly alloy remelting, and the metallurgical reaction is not significant The process characteristic of smelting cast iron in electric furnace is that the undercooling degree of alloy increases after molten iron remelting, and the superheat temperature is higher, which brings new problems to the quality control of cast iron. After hot metal…

Process Diagram of Water Cooled Metal Mold Centrifugal Casting melting Add raw materials (scrap steel, pig iron, recycled materials, etc.) into the melting furnace (induction furnace or cupola) and adjust their composition. When the composition meets the process requirements, pour molten iron into the frequency conversion holding furnace for spheroidizing. If the sulfur content in molten iron exceeds the standard, desulfurization treatment shall be carried out first. Spheroidization When the composition and temperature of molten iron meet the process requirements, the spheroidizing agent is added to the molten iron to change the flake graphite in the molten iron into spherical…

1) Amorphous materials have low moisture absorption, and the water absorption of PPO is very low. However, the moisture will cause defects such as silver wire and bubble on the surface of the product. Therefore, the raw materials can be put in an 80~OOC oven and dried for 1-2 hours before use. 2) The molecular bonds of PPO are rigid, the glass transition temperature is high, and it is difficult to orient, but it is difficult to relax after forced orientation. Therefore, the residual internal stress in the product is relatively high, which generally requires post-processing. 3) PPO is an…

Metal Powder Injection Molding (MIM) is a new powder metallurgy near net shape forming technology that introduces modern plastic injection molding technology into the field of powder metallurgy. The basic technological process is as follows: first, the solid powder and organic binder are uniformly mixed, then granulated, injected into the mold cavity with an injection molding machine under the heating and plasticizing state (~150 ℃) for curing and forming, and then the binder in the forming blank is removed by chemical or thermal decomposition methods, and finally the final product is obtained through sintering and densification. Compared with the traditional…

High grade gray cast iron generally refers to gray cast iron above HT250. In the production process, it can be roughly divided into the following forms: one is inoculation cast iron; The other is alloy cast iron (rare earth gray cast iron is mainly introduced here). Now let's talk about my own views and understanding on the two kinds of high grade gray cast iron casting. 1、 Inoculated cast iron In gray cast iron, graphite exists in the form of flake, which seriously damages the properties of iron matrix. In order to improve the mechanical properties, the number of graphite…