Friction Welding of Piston Rods

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What are Piston Rods?

Piston Rods

The piston rod is a fundamental and critical component of every hydraulic or pneumatic cylinder. It is a precision-machined length of hard chrome-plated, cold finished steel bar which transmits the force created by the piston to the machine component doing the work. Although a vital part of the hydraulic cylinder, the rod is often taken for granted until a problem arises. Hydraulic cylinders used for mobile applications like earthmoving equipment, cranes, tippers etc., have the rod end with an eye.

MIG Welded Piston Rods

Traditionally the eyes were MIG welded to the piston rod end. However, this has the following challenges

  • Special End Preparation for both Rod-eye and piston rod
  • Multiple layers of welding
  • Distortion effect, large heat-affected zone and grain growth at weld thus weakening the weld
  • A filler material used for welding
  • This process generates a lot of obnoxious fumes and arc.

Friction Welding as an alternative

Rotary Friction welding is widely accepted as a competitive and proven alternative to several bonding methods such as MIG, Laser, flash-butt, resistance welding etc. This is an ideal solution to eliminate the challenges faced by the MIG welding process. Because of the all-round advantage it provides, Friction welding is now widely adopted by a lot of manufacturers. Still, there are a lot of manufacturers out there who are either not aware of this joining process or have misgivings on adopting it. Moving to a Rotary Friction Welder gives an end user the following benefits: -

Flexibility in Production Process

Friction welding can be the last operation as the induction hardened, chrome-plated rod can be welded to the forged eye. This gives flexibility in planning the sequence of operations on the shop-floor.

Reduction in Material Costs

Only the rod eye portion is forged and the remaining part is Friction Welded to the rod eye. This results in an approximately 5%-20% reduction in material costs. The savings vary based on the job dimensions.

Overall machining time can be reduced by approximately 15% by pre-machining the Rod and Forged ends.

Process Benefits

A Friction Welder brings a host of benefits over the traditional welding processes due to its inherent clean, predictable and fast nature. Below are some of the key benefits a customer can get by adopting this process

  • The welded area is stronger than the weaker parent material. This results in a better weld strength (roughly 20% more) than any other process.
  • Faster cycle times
  • No special edge preparation needed in most of the cases
  • Process quality is predictable and repeatable throughout the lifecycle of the machine. This results in a significant reduction of in-process rejections.
  • No requirement for filler material (roughly 10% material cost saving)
  • Extremely low heat affected zone.
  • Very low energy consumption as compared to MIG welding.
  • No arc/fumes.

You can have a look at the welding process of a Piston Rod on one of our Rotary Friction Welders here.

As with any industry, as newer technologies emerge, those who jump onto the bandwagon get an early mover advantage. If you haven’t yet moved to adopt this technology, we would be happy to introduce you to this process. We invite you to talk to our welding experts to see how Friction Welding can help you produce your best part ever.