Page 221 - CITS - Welder - Trade Theory

WELDER - CITS

Friction welding process: principles, application,
advantages

Objectives : At the end of this lesson you shall be able to
• describe the friction welding process
• explain the friction welding application
• explain the friction welding advantage.

Friction welding
Principle: Friction welding uses friction to create heat to fuse two pieces of metals together. This process is used
mainly in butt welding of large sections round rods, very heavy tubes and pipes.
Method of welding: No external heat is supplied. One of the pieces is made to rotate. The ends of the parts to be
joined are then brought together under a light pressure. The resulting friction between the stationary and rotating
parts develops the heat required to form the weld. As the metal surfaces reach the plastic stage, they are forced
together under a much higher pressure. The process produces a clean metal-to-metal welding surface. (Fig 1)
A 1/2” diameter low carbon steel rod with welding temperature of 1650ºF can be joined with a contact pressure
in the range of 5000 to 10000 pounds/inch while rotating at approximately 3000 rounds per minute for about 5
second. Medium and high alloy steels require heating pressure (Contact Pressure) ranging from 10000 to 30000
pounds/inch and forging pressure between 15000 to 60000 pounds/inch.

Fig 1

Applications
Metals that can be welded by the friction welding process include Carbon Steel, Steel Alloys. Stainless Steel,
Copper, Aluminum and Titanium.
Advantages over metallic arc welding
Itis more suitable process for joining dissimilar metals.
- The process produces a clean metal-to-metal welding surface.
- A highly skilled welder is not required.

- A weld with less defects can be obtained.
- No filler rod or electrode is required.
- Power consumption is less. Limitations
- The machine is costly.

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CITS : C G & M - Welder - Lesson 61-76 CITS : C G & M - Welder - Lesson 61-76