Casting flange, the shape of the blank is accurate, the processing volume is small, the cost is low, but there are casting defects (pores, cracks, inclusions); the internal flow of the casting is poor (if it is a cutting part, the streamline type is worse);
Forged flanges generally have lower carbon content than cast flanges and are less prone to rust. Forgings have better streamlined shape, denser structure and better mechanical properties than cast flanges;
If the forging process is improper, the grain will be large or uneven, and the hardening crack will occur. The forging is higher than the casting flange.
Forgings can withstand higher shear and tensile forces than castings.
The advantage of the casting is that it can produce a more complicated shape and the cost is relatively low;
The advantage of the forging is that the internal structure is uniform, and there are no harmful defects such as pores and inclusions in the casting;
Different from the production process, the difference between the cast flange and the forged flange, such as the centrifugal flange, is one of the cast flanges.
Centrifugal flange is a precision casting method production flange. This kind of casting is much thinner than ordinary sand casting structure, and the quality is improved a lot. It is not easy to have problems such as loose structure, pores and trachoma.
First of all, we need to understand how the centrifugal flange is produced and processed by centrifugal casting to produce a flat welded flange. The product is characterized by the following process steps:
- The selected raw material steel is smelted in a medium frequency electric furnace to make the molten steel temperature reach 1600-1700 ° C;
- Preheating the metal mold to 800-900 ° C to maintain a constant temperature;
- Start the centrifuge, and inject the molten steel in step 1 into the metal mold after preheating in step 2;
- Castings are naturally cooled to 800-900 ° C for 1-10 minutes;
- Cool with water to near normal temperature, demoulding to remove the casting.
Let’s take a look at the production process of forged flanges:
The forging process generally consists of the following steps: selecting high-quality billet blanking, heating, forming, and forging cooling. Forging processes include free forging, die forging and film forging. At the time of production, different forging methods are selected according to the quality of the forgings and the number of production batches.
The free forging productivity is low, the machining allowance is large, but the tool is simple and the versatility is large, so it is widely used for forging a single piece and a small batch of forgings with a simple shape. Free forging equipment includes air hammers, steam-air hammers and hydraulic presses, which are suitable for the production of small, medium and large forgings. Die forging has high productivity, simple operation, and easy mechanization and automation. The die forgings have high dimensional accuracy, small machining allowance, and reasonable distribution of the fiber structure of the forgings, which can further improve the service life of the parts.
The basic process of free forging: When free forging, the shape of the forging is gradually forged by some basic deformation process. The basic processes of free forging are upsetting, lengthening, punching, bending and cutting.
- Upsetting Upsetting is an operation process in which the raw material is forged in the axial direction to reduce its height and increase the cross section. This type of process is commonly used for forging gear blanks and other disc-shaped forgings. The ups and downs are divided into two types: all upsetting and partial forging.
- Pulling out Lengthening is a forging process that increases the length of the blank and reduces the section. It is usually used to produce shaft blanks, such as lathe spindles and connecting rods.
- Punching A forging process in which a punch punches a through hole or a through hole without using a punch.
- Bending A forging process that bends the billet into a certain angle or shape.
- Torting A forging process that rotates a portion of a blank relative to another portion by a certain angle.
- Cutting The forging process of dividing the blank or cutting the material.
Second, die forging
The die forging is collectively referred to as model forging, and the heated billet is placed in a forging die fixed to the die forging device to be forged.
The basic process of die forging The process of die forging: cutting, heating, pre-forging, final forging, punching, trimming, quenching and tempering, shot peening. Commonly used processes are upsetting, lengthening, bending, punching, and forming.
Common die forging equipment Common die forging equipment includes die forging hammer, hot die forging press, flat forging machine and friction press.
Generally speaking, forged flanges are of better quality, generally produced by die forging, with fine crystal structure and high strength, and of course the price is more expensive.
Whether it is cast flange or forged flange, it is a common method of manufacturing flanges. See the strength requirements of the parts to be used. If the requirements are not high, you can also use turning flanges.
Third, the cutting flange
The inner and outer diameters of the flange and the thickness of the disc are cut directly on the middle plate, and the bolt holes and water lines are processed. The flange thus produced is called a cut flange, and the maximum diameter of such a flange is limited to the width of the middle plate.
Fourth, the rolling flange
The process of cutting the strips with the middle plate and then rolling them into a circle is called rolling, and is used for the production of some large flanges. After the winding is successful, the welding is performed, and then the flattening is performed, and then the process of the water line and the bolt hole is processed.
Source: China Stainless Steel Flanges Manufacturer – Yaang Pipe Industry Co., Limited (www.yaang.com)