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Direct Drive Friction Welding Direct Drive Friction Welding

Direct Drive Friction Welding

The origins of Direct Drive Friction Welding go back more than 100 years, but MTI has taken the process into the new millennium, with expertise, equipment and innovations that address the 21st century needs of manufacturing.

MTI is the world leader in designing and manufacturing Direct Drive Friction Welders, and is the only company offering a full line of all three main types of friction welding machines.

Process Overview

Direct Drive Friction Welding is one of three basic types of rotational friction welding, the other two are Inertia and Radial. Friction welding, in general, is a Solid State Process as it does not cause melting of the parent material during the welding process.

In the Direct Drive weld cycle, one work piece is held stationary and the other piece is attached to a spindle that is rotated at a constant speed by an electric motor. The work pieces are moved together and an axial force is applied. As the faying surfaces (surface interface) rub together, they are heated to a plastic state while axial force is continued for a predetermined time or until a preset amount of upset takes place - where Upset is defined as a linear measurement of the material displaced during the weld cycle. When this point is reached, the drive is disengaged and a brake is applied. The welding (or forge) force is maintained, or even increased, for a time after rotation ceases. The resulting joint is of forged quality.

Direct Drive Friction Welding has nearly unlimited applications and has been used by MTI to weld cutting tools, agricultural machinery, automotive parts, oil field pieces, military equipment, spindle blanks and bimetallic materials.

Advantages & Benefits of Direct Drive Friction Welding

  • Less rigid tooling requirements reduce machine and equipment design costs
    In using an electric motor to apply constant energy (in the form of RPM) over a longer period of time, Direct Drive Friction Welding avoids instantaneous torque peaks - like those created in Inertia Friction Welding when a flywheel comes to an abrupt stop. This lower weld torque puts less strain on the machine frame so lower cost and less complex equipment designs can be used to generate extremely high-quality welds.
  • Length control of welded components with advanced length control technology
    Direct Drive Friction Welding can provide consistent length control or Upset control to 0.3mm (0.015 inches) using standard control techniques– precision that can be enhanced even further with MTI’s advanced length control technology. 
  • Reliably controls post-weld orientation 
    Able to maintain 1-degree angular orientation after welding, Direct Drive Friction Welding processes can be used to join complex parts that are radially aligned after welding.
  • Longer weld cycle enhances material strength
    Because energy is constantly and evenly supplied (using the spindle drive motor) over a period of time, the joint strength of some metals and alloys (especially higher carbon content materials) are maintained through the welding process, creating stronger welds and high joint efficiencies.
  • Fast and easy set-up changes save time and money on the shop floor
    Unlike an Inertia Friction Welder, a Direct Drive Friction Welder utilizes an electric motor instead of a flywheel to supply the energy for welding. This means that on Direct Drive Friction Welders, part set-up changes for different parts are faster with less effort than similar change-outs on Inertia Friction Welders because of the flywheels. 
  • Strong welds for all geometries
    Particularly well-suited for the production of large diameter bars, like those used in hydraulic cylinder rods and other tube-to-tube and bar-to-bar configurations, Direct Drive Friction Welding produces strong, consistent joints for a variety of weld interfaces. In the case of large cross-section solid welds, the use of Direct Drive Friction Welding allows welding of the same cross-section with less forge force than an Inertia Friction Welder. Therefore, for the same diameter solid bar a smaller Direct Drive Friction Welder can be used.
  • Narrow heat-affected zone retains parent material properties
    A narrow heat affected zone protects the integrity of the parent materials involved in the weld, retaining more uniform properties throughout the newly created part - providing higher joint efficiencies, and creating a stronger weld. 

MTI’s Advanced Technology Direct Drive Friction Welders

With hundreds of patents, ongoing research and development, more than 30 years of experience and with more than 600 machines in operation around the world, MTI sets the standard for value-added features that maximize your Direct Drive Friction Welding processes.

MTI’s HYBRID version of Direct Drive Friction Welders use AC or DC variable speed drives that eliminate clutches and brakes. Proportional hydraulic controls guarantee smooth up and down force control. Through manipulation of deceleration times and forge force ramp up time, welds can be made ranging from near Inertia Friction welds to classic Direct Drive Friction welds.

Direct Drive Friction Welders from MTI offer these value-added features:

  • Automation
  • Flash Removal
  • Enhanced Upset Control through Torque Modulation
  • Improved Length Control through Dynamic Profile Modulation
  • Advanced Radial Orientation Capability through our Proprietary Control System
  • Manufacturing Cell Integration (including Material Handling, Automatic Loading and Unloading, Robot Integration, Flash Removal, Bar Coding, Quality Control, Part Destruction)
  • Custom Design Machine Diagnostics and Maintenance Schedule for Full Preventive Maintenance
  • Custom Applications