Forged PM = Clean forge

Drivetrain electrification poses new challenges to increased component performance and reduction in mass for maximized driving distances and efficiency. Forged PM supports these demands by forging differently. Distinct clean powder metal alloys are fundamental: powder forging steels have a high degree of cleanliness, uniform chemistry and carefully controlled additives. A preform is made by powder compaction and sintering; providing a tailored alloy composition, optimum mass distribution, geometry and near-surface conditions to perfect the flow of material during forging. In a single high temperature forging stroke, components are forged to the final shape.

GKN's 2016 MPIF award-winning Differential Gear Set included forged powder metal differential gears, which was a first-time usage of forging technology in its application. The Differential Gear Set included a side gear, two pinion gears, a locking side gear and a lock plate, and was used in the rear axle differential on the Ford F-150 light truck.

We are the one-stop solution provider in Forged PM (FPM) technology. Our engineers support customers with optimized designs and high durability capability. Our FPM solutions advantages:

  • Materials enable system downsizing, reducing masses and inertias by 15 to 20 percent
  • Materials outperform wrought steels by 15 to 30 percent in durability
  • Forgings provide consistent and repeatable datum features without draft angles and flash lines
  • Technology offers efficient designs and complex, near-net shapes with minimal machining stock

FPM Advantages

The FPM process utilizes compressive forces, aiding in high deformation and lateral material flow to produce desired geometries and material properties. 

The forging process strengthens materials through grain structure refinement, while high levels of deformation ensure extensive shearing to provide a strong microstructure. The result is a fine grain size, homogenous chemical distribution without wrought alloy segregation, and a uniformed response to heat treatment. 

FPM components are produced from a range of alloys, including equivalents of plain carbon steel, low alloy steel and alloys which can be heat treated to a hardness of Rockwell C 60.

The FPM Process

FPM differentiates from traditional processes in that a product's complex and irregular net-shape geometries can be produced.

Carefully-engineered preforms, a combination of precise material distribution and high material formability, enable forging of these complex and irregular product geometries. 

These intelligent preforms allow for components to be produced with a single stroke of the forging press - versus three forming strokes - with minimal amounts of flash and waste.

Material utilization is 20-50 percent higher than in traditional bar forging, along with better die filling and higher complexity of as-forged features. 

Process Comparison FPM vs Wrought Forging

FPM products allow unique designs and alloys that outperform the highest alloyed steels.

FPM materials outperform conventional 16/20MnCr5 wrought steels in durability by 30 percent. Even high-alloyed wrought 18CrNiMo7-6's capabilities are significantly below FPM material capabilities.

This durability capability supports downsizing mass and increasing torque requirements with its proven history in validated products and a growing number of series applications.

Performance Comparison FPM Durability

An automotive and PM industry first: A FPM Differential Gear Set used in an Electronic Locking Rear Differential.

FPM achieved a higher performance compared to competing technology in gear set fatigue performance, impact resistance, locking system durability and the safety factor. 

Performance requirements were exceeded due to the optimization of geometry, metallurgy and process for five components per differential:

  • Side gear
  • Pinion gears (2)
  • Locking side gear
  • Locking plate

GKN's FPM Differential Gear Set establishes a benchmark for differential gear performance: increased delivery torque capacity, facilitated achievements of future fuel efficiency, and enabled downsizing of future systems.

Case study: Differential Gear Set

GKN has produced the highest horsepower forged powder metal production Connecting Rod in the PM and automotive industries.

The application is a high performance, supercharged 6.2L V-8 engine, SAE-certified at 650 hosepower at 6,400 RPM and 650 lb.-ft. of torque at 3,600 RPM. 

FPM offers the highest strength and a lightweight design to reduce reciprocating mass, along with quicker REV capability. The design takes advantage of lightweighting through machined lightening slots and additional lightening features while maintaining high load capacity.

FPM replaced a titanium material which was expensive, had low supply, and offered an extensive lead time. 

This technology establishes a benchmark in performance for production FPM Connecting Rods.

Case study: Performance Connecting Rod