How to distinguish between forged flanges and cast flanges

- Sep 11, 2018-

How to distinguish between forged flanges and cast flanges

1. Casting flange
Both the cast flange and the forged flange belong to the common manufacturing method of the flange. The forged flange is invented on the basis of the cast steel flange, and its strength is much higher than that of the cast steel flange. As for the choice of cast flange or forged flange, it depends on the strength requirements of the parts to be used. According to the flange material: stainless steel flange, carbon steel flange, alloy steel flange according to type: plate type flat welding flange, neck flat welding flange, butt welding flange, blind flange flange cover, loose sleeve Flange, threaded flange, socket weld flange, etc.
Casting flanges can be used to create more complex shapes with lower costs; generally integral flanges (such as valves) are cast. The flanges are cast, the shape of the blank is accurate, the processing amount is small, the internal flow of the casting flange is poor, and there are casting defects (cracks, sand holes, pores, inclusions).
2. Forged flange
Forgings can withstand higher shear and tensile forces than castings. 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. The advantages of forged flanges are uniform internal structure, no porosity in the castings, inclusions, etc. Harmful defects, improper forging process will also appear large or uneven grain, hardening crack phenomenon, forged flange quality is better, generally by die forging production, fine crystal structure, high strength, forging is higher than casting flange, price Also more expensive than casting flanges.
The forging process is generally for blanking, heating, forming, and post-forging cooling. According to the quality of forgings, the number of production can choose different forging methods.

Carbon steel flange.jpg

 The common forging methods are free forging and die forging.
1. Free forging is widely used for forging single-piece and small batch forgings with simple shape. The free forging processing has large margin and low productivity, but the versatility is high and the tools are simple. The basic process of free forging is to gradually forge the forging blank by some basic deformation process. The basic processes of free forging are upsetting, lengthening, punching, bending and cutting.
 2. The 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 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. Common die forging equipment includes die forging hammer, hot die forging press, flat forging machine and friction press. The basic process of die forging: cutting, heating, pre-forging, final forging, common processes are upsetting, lengthening, bending, punching, forming.