Production Techniques of Flanges

The production techniques of flanges fall into four major types: forging, casting, cutting, rolling.
Cast Flange
Pros: Precise, sophisticated shape and size
         light workload
         low cost
Cons: Defects such as pores, crack, containing impurities
          Poor internal streamline (worse in cutting parts)
Compared to cast flange, forged flange is generally with lower carbon content and better in rust prevention, streamline, compact structure, mechanical capacity.
Improper forging process will cause bigger or uneven grain, hardening, seaminess and higher cost.
Forged flange can withstand stronger shearing force and tensile strength. And due to its well-distributed inner, it won’t have defects such as pores, impurities containing like cast flange.
The production processes of these two kinds of flanges are quite different. For example, centrifugal flange, made in a sophisticated casting method, belongs to cast flange.
The structure of this higher-quality cast flange is way finer than that of common, sand molded type.
First we need to understand the production process of centrifugal flange. Centrifugal casting is a process of making welded flange, which is processed by the following typical process steps:
  • Step 1: Put the picked raw steel materials into a medium-frequency furnace for melting, and raise the temperature of liquid steel to 1600℃~1700℃.
  • Step 2: Preheat the metal mold between 800℃ and 900℃, and maintain the temperature.
  • Step 3: Turn on the centrifuge machine, pour the liquid steel (step 1) into the metal mold (step 2).
  • Step 4: Wait until the temperature of the casting drops between 800-900℃, and maintain the temperature for 1-10 minutes.
  • Step 5: Water-cool the casting until its temperature is close to 25℃, and take it out from the mold.

Forged Flange
The production process includes selecting high-quality steel billet, heating, molding, cooling after forging, and methods like open die forging, closed die forging (impression die forging), swage forging.
Open die forging is a low-efficiency and heavy-workload method, but its versatility and easy-to-use tools are pretty suitable for simple-shaped pieces and small-lot production. For forged pieces from different sizes, there are air hammer, steam-air hammer, hydraulic press, etc.

Closed die forging is high-efficiency, easy-operation, and painless for mechanization and automation. The lifespan of parts can further prolong if the size of the part is more precise, structure more reasonable, machining allowance smaller.

Production Process of Forged Flange

forged flange process - Production Techniques of Flanges

The forging process is usually composed of the following processes, namely, the selection of quality steel billet, heating, forming and cooling. The forging process has a free forging, die forging, and tire forging. In the production, press the mass of the forging parts, the quantity of the batch of different forging methods.

It is widely used in forging simple pieces and small batches of forging parts. The free forging equipment is equipped with pneumatic hammer, steam air hammer and hydraulic press, which are suitable for the production of small and large forgings. High productivity, easy operation, easy mechanization and automation. The size of die forging is high, the machining allowance is small, and the fabric of the forging is more reasonable, which can further improve the service life of the parts.

The basic process of free forging: when forging, the shape of the forging is gradually forged through some basic deformation process. The basic process of forging and forging is upbold, long, piercing, bending and cutting.

Upset upsetting is the operation process that reduces the height of the raw material and increases the cross section. This process is used for forging gear billets and other disc shaped forgings. The heading is divided into full heading and partial forging.

The length of the shaft is increased by the length of the billet, the forging process of the reduction of the section is usually used to produce the spindle such as the lathe spindle, the connecting rod and so on.

  • The forging process of punching holes through holes or holes in the blank.
  • The forging process that bends the blank to a certain Angle or shape.
  • Twist the process of turning a part of the billet into a certain angle.
  • The forging process of cutting down the raw material or cutting head.
  • Second, the die forging

The die forging is known as the forging of the model, which is placed in the forging of the forging machine which is fixed on the die forging equipment.

The basic process of die forging: material, heating, pre-forging, finishing, finishing, cutting, trimming and blasting. The common technique is to upset, pull, bend, punch and form.

The commonly used die forging equipment has die forging hammer, hot die forging press, flat forging machine and friction press.

Generally speaking, the forging flange is of better quality, usually through die forging, the crystal structure is fine, the strength is high, and of course the price is more expensive.

Whether casting flange or forging flange are commonly used in manufacturing methods, see the need to use the strength of the components, if the requirements are not high, you can choose to turn the flange.

  • Upsetting – Axially forge the blank so as to increase its cross-section by compressing its length. This is often used in forging wheel gears or other disc-shaped pieces.
  • Drawing out – To increase the length of the blank by decreasing its cross-section. It usually works for axial blank, like lathe spindles, connecting rods.
  • Piercing – To pierce a hole or hollow on the blank by a center punch.
  • Bending – To bend the blank into a certain angle, or shape.
  • Twisting – To turn a part of the blank around.
  • Cutting – To cut the blank or remove the remnant.

Closed die forging
After heating, the blank is placed and shaped in a die resembling a mold.
The basic procedures includes: blanking, heating, pre-forging, finish forging, stamping, trimming, tempering, shot blasting.
Methods: upsetting, drawing out, bending, piercing, molding.
Equipments: forging hammer, hot forging press, upsetting machine, friction press, etc.
Generally, workpieces producing through closed die forging have finer crystal structure, higher intensity, better quality and apparently more expensive price tags.
Both casting and forging are common used flange manufacturing methods. If the intensity of the needed part is undemanding, then lathing is another feasible option.

Cut Flange
A disc that directly cut on the middle plate, with bolt holes, waterlines, reserved internal and external diameters, thickness. Its max diameter is within the limit of the breadth of the middle plate.
Rolled Flange

It is a rolled strip cut by the middle plate, mostly in large size. The producing procedures of rolled flange, in sequence, are: rolling, welding, planishing, making waterlines and blot holes.

Source: China Flanges Manufacturer – Yaang Pipe Industry (www.steeljrv.com)

(Yaang Pipe Industry is a leading manufacturer and supplier of nickel alloy and stainless steel products, including Super Duplex Stainless Steel Flanges, Stainless Steel Flanges, Stainless Steel Pipe Fittings, Stainless Steel Pipe. Yaang products are widely used in Shipbuilding, Nuclear power, Marine engineering, Petroleum, Chemical, Mining, Sewage treatment, Natural gas and Pressure vessels and other industries.)

If you want to have more information about the article or you want to share your opinion with us, contact us at sales@steeljrv.com
Please notice that you might be interested in the other technical articles we’ve published:
  • What are orifice flanges

  • How to get high quality flanges

  • How to get high quality alloy flanges

  • How to get high quality Carbon Steel Flanges

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