GKN’s Sinter Metals has published an article on the development and increased performance offered by its Powder Metallurgy transmission carriers. The company has been producing PM carriers for planetary gear sets since the 1990s, over a period which has seen designs evolve from simple forms to complex systems with many functional features.
As CO2 reduction requirements put increasing pressure on the automotive industry, automakers are developing higher speed transmissions for improved efficiency and fuel economy, with 8-, 9- and 10-speed automatic transmissions becoming the standard. Due to its net shape capabilities, PM technology is a key enabler for complex transmission designs.
GKN’s steel PM carriers are designed to reduce machining chips and weight, while increasing part rigidity. The company’s designs eliminate the need for backing plates and one-way clutches, reducing the space and weight taken up by the carrier. During compaction, lubricating features are integrated into the carrier itself.
In June 2017, GKN Sinter Metals was awarded an MPIF award for its Planetary Carrier Assembly. The sinter-brazed copper-steel assembly, comprised of a cage and a flanged hub, goes into the new 10-speed transmission for the Ford F-150 pickup and requires only simple milling and turning operations to hold the tight tolerances on the bearing bores, pinion pin shaft holes, and thrust faces.
The company also stated that GKN’s proprietary high-performance aluminium MMC materials further reduce mass and inertia in its planetary carriers. The lower density of aluminium makes it possible to reduce mass by 60% from the equivalent steel part, while still allowing the part to perform at the working temperature of a modern automatic transmission.
Alan Taylor, Lightweight Technology, GKN Powder Metallurgy, explained, “The aluminium MMC is based on technology that has been used in aerospace for many years, but was developed to provide improved performance at lower cost than aerospace MMCs. This technology was introduced into the market place in mid-2016 and is serial production.”
GKN Sinter Metals expects CO2 reduction requirements to continue to dominate automakers’ production decisions. Therefore, a carrier’s ability to adapt to functionality and design requirements is crucial for optimal performance.
“In my opinion, our ability to understand these applications well enough to provide a customer-specific solution is what puts us on top in the carrier market,” concluded Paul Cook, Vice President Operations, Global Large Segment, GKN Sinter Metals.