Federal-Mogul
Powertrain, a division of Federal-Mogul Holdings Corporation has developed a
range of piston technologies designed to support heavy-duty diesel engine
manufacturers in reducing fuel consumption and meeting the emission
requirements of Euro-6 and beyond. According to a press release from
Federal-Mogul, advanced piston architectures, manufacturing processes,
materials, and treatments that increase durability and reduce friction have
been applied to both steel and aluminium pistons. The company will present its
range of piston products at the IAA Commercial Vehicles Show in Hannover from
September 23 to October 2, 2014.
Norbert
Schneider, director, Piston Application Engineering, Federal-Mogul Corporation explained
that the higher peak cylinder pressures (PCPs) used to increase combustion
efficiency are only made possible through advances in piston technology that
provide durable solutions under increased thermal and mechanical loads,
“In
addition to enabling more efficient combustion, our pistons contribute to
further reductions in fuel consumption and CO2 emissions by operating with
reduced friction,” he added.
Pistons
made from aluminium or steel have some unique properties. Aluminium is lighter
and conducts heat better, and the higher strength of steel offers advantages
when faced with very high peak cylinder pressure. Aluminium is still the first
choice for smaller sizes of 120mm or below whereas steel is the established
solution for truck applications with bore sizes of 130mm or more. A gradual
trend is also visible for steel piston applications in the mid-size bore
sector, especially for PCPs in excess of 210-220 bar.
Arnd
Baberg, Chief Engineer, Piston Product Engineering, Federal-Mogul noted that
while his company is the world’s largest supplier of steel pistons for
heavy-duty trucks, its extensive range of proprietary technologies for
aluminium pistons means it can provide customers with a greater choice of
products when PCP is lower than around 220 bar.
Aluminium Piston Technology
The
press release further stated that Federal-Mogul has extended the performance of
aluminium pistons by improved cooling through advanced architecture that
locates the oil-cooled gallery closer to the critically hot region than any
conventional piston. This has been made possible by state-of-the-art 2D
ultrasonic inspection techniques that ensure consistent casting quality in
every finished piston.
The
combustion bowl strength of any diesel piston often limits the maximum
temperatures and pressures that can be safely used because fatigue cracking of
the bowl rim and bowl base can occur, originating at free silicon particles in
the aluminium. Federal-Mogul’s proprietary DuraBowl process uses a controlled
re-melting of the bowl rim and/or the bowl base to refine the grain size of the
silicon to just one tenth of its original size, significantly extending the
fatigue life of a cast piston.
To
improve engine efficiency, Federal-Mogul has developed the EcoTough Diesel
coating that reduces friction between the piston skirt and bore surface by up
to 13 percent, compared with conventional graphite coatings. EcoTough Diesel
uses solid lubricants and a carbon fibre reinforced polymer base to provide
lower friction, higher scuff resistance and improved wear resistance.
Steel Piston Technology
Tested
at up to 300 bar PCP, Federal-Mogul’s Monosteel pistons use the latest
evolution of the company’s friction-welded architecture, that enables superior
cooling efficiency and minimum weight. Having produced over eight million
Monosteel pistons since their introduction in 2003, Federal-Mogul continues to
refine the technology, which provides an optimal solution for the most arduous
of applications.
The
high loads carried by the piston pin in modern heavy-duty engines means almost
all pistons require a highly precise pin bore without using pin bore bushes.
Federal-Mogul has developed a unique process using High Precision
Electro-Erosion Machining (HPEEM) which removes an exact amount of material,
thus precisely shaping the piston pin bore, enabling improved load capacity and
reliability.
Steel
pistons are available with the same EcoTough Diesel coating that reduces
friction on aluminium pistons. In addition, Federal-Mogul has developed a
bowl-protecting coating which contains nanodiamonds in a chrome layer to
reflect heat and reduce carbon build-up and bowl rim erosion.
“Because
we are market leaders in the technology of both steel and aluminium pistons for
heavy-duty diesel engines, we can provide the optimum solution for each
customer without compromise, based solely on meeting the specific requirements
of the application,” said Schneider.