Withstanding the Pressure, Surpassing the Standard
As emission norms get stricter, engines lighter and more efficient, and customers more demanding, pistons have to work reliably under combustion temperatures reaching from 1000 to 2500, and ignition pressures of up to 250 bar. Additionally, OEMs are offering million-mile warranties to end users.To keep up with these demands, a variety of new materials and treatments are being developed by OEM vendors.
Garima Global works with such leading vendors of pistons in India to manufacture cutting edge pistons for the aftermarket industry. Our customers also trust us to source pistons and piston rings, and assemble them with our cylinder liners to make liner-piston kit sets. Garima Global supplies these AutoGRACE brand pistons to discerning customers worldwide.
Pistons serve three important functions in an IC engine:
Size Range of Piston in AutoGRACE Brand
The crown and the body of the piston may incorporate various design elements to serve a wide variety of purposes.
Since monometal pistons usually exhibit high thermal expansion, steel or ceramic struts are cast into the piston boss area especially when used in cast iron engine blocks. This restricts the expansion of the piston thus enabling smaller piston block clearance.
Diesel engines operate at higher temperatures and pressures than gasoline engines, which causes excessive loads on the piston crown. To re inforce the top one or two ring grooves, Ni resist or ALFIN ring carriers are cast into the piston. These ring carriers made from high strength, austenitic cast iron increase the wear resistance and fatigue resistance of the grooves at elevated temperatures. Dual Ni Resist, or ring carriers with two ring grooves are also used in particularly heavy duty engines.
In turbo-charged super-charged inter-cooled after-cooled engines, thermal loads tend to be even higher. To counter these, a cooling gallery may be cast into the crown of the piston using a salt core. Lubricating oil is sprayed into this gallery from the crankcase which reduces the temperature of the bowl rim, top land and ring grooves, thus guaranteeing longer life.
Pistons used in engines that operate under especially high loads require a bushing, similar to a con rod small end bushing, to be installed on the piston pin bore. This bushing serves to improve lubrication between pin and piston.
There are literally thousands of piston crown designs:
Allow the piston to approach extremely close to the cylinder head without hitting the valves thus maximizing compression ratio.
Are especially prevalent in diesel pistons since these engines do not have the ignition phase. Cavities of various sizes and shapes are cast machined into the piston crown inside which combustion occurs. The geometry of the bowl is designed to maximise combustion thus producing higher power.
To swirl and squish or direct the fuel-air mixture are cast machined into the piston head. They increase the turbulence of air fuel mix as the piston approaches TDC which causes better mixing and more complete combustion, again maximizing power output.AutoGRACE pistons have been developed with the exact head geometry as per OEM specifications, thus ensuring your engine gives the same power output and efficiency as a brand new engine
Vast majority of the applications utilize aluminium pistons due to their light weight, good thermal conductivity and structural rigidity. Since pistons reciprocate within the cylinder liner 800 to 8000 times per minute their light weight lowers inertia, decreases load on the connecting rod, and increases engine efficiency and safety. Also the high thermal conductivity of aluminium helps dissipate the heat generated from combustion into the block. Good machinability and simple casting techniques are an added advantage of this material from the production standpoint.
These constitute the simplest design, material used is high temperature resistant aluminium alloy cast using gravity die casting process. They are competitively priced, can be manufactured in smaller production lots and offer adequate performance for lower performance engines.
These basic pistons are enhanced with certain elements to reduce their thermal expansion and improve rigidity, strength, wear resistance etc. as summarized below.
Most commonly used alloy with 12 Si 1 approximately of Cu, Ni and Mg. Provides a balanced combination of strength and high-temperature resistance.
Developed for higher strength at elevated temperatures with higher percentages of Cu and Ni. Used in especially heavy duty engines.
With Si ranging from 18 to 24, these alloys offer lower thermal expansion and high wear resistance, but at the cost of lower strength. They are used in lighter, high-speed engines like light-duty automotive applications.