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AutoGRACE®
Camshafts

Perfect Timing – The Catalyst that Transforms Force into Work

Camshafts are the masters that control the timing of the complete engine assembly. Their lobes open and close the engine valves. In many engines they also actuate fuel injectors at just the precise moment to achieve maximum combustion efficiency. As such wear resistance and perfect geometry of the lobes and the journals are of prime importance.

PRODUCT

Camshafts serve following functions in an IC engine:

  1. VALVE TIMING: Open and close the inlet and exhaust valves in sync with the piston movement to enable air + fuel mix to enter the combustion chamber, and to seal the chamber during the combustion event.
  2. INJECT AIR + FUEL MIXTURE: Sometime between the end of the compression stroke and the beginning of the power stroke, camshaft actuates the injector to spray the air + fuel mix into the chamber to initiate combustion.
  3. ENGINE BRAKING: Sometimes camshafts have special mechanisms to increase engine drag during coasting or overrun by, for example, opening the exhaust valve for a short period around TDC of compression stroke, especially in medium and heavy duty vehicles.

PRODUCT RANGE

Garima Global is only of the leading companies in India for engine camshafts. We specialize in developing custom made camshafts as per our customers’ requirements.

Size Range of Piston Rings in AutoGRACE® Brand

SPECIFICATION FROM TO
Suitable for No. of Cylinders 1 16

APPLICATIONS

Garima Global supplies components for a wide variety of on-road, off-road, industrial and stationary applications such as: automotive (light duty) and light commercial, trucks (heavy duty), tractors (agricultural), earthmoving and construction machinery, generators, irrigation pumps, and defence / special purpose vehicles.

The brands for which we manufacture and export aftermarket products are Caterpillar, Chevrolet, Chrysler, Citroen, Cummins, Daewoo, DAF, Daihatsu, Detroit Diesel, Deutz, Fiat, Ford, Hino, Honda, Hyundai, International, Isuzu, Iveco, John Deere, Kamaz, Kia, Komatsu, Kubota, Land Rover, Leyland, Lister Petter, Lombardini, Mack, Mahindra, MAN, Massey Ferguson, Mazda, Mercedes Benz, Mitsubishi, Navistar, Nissan, Onan, Perkins, Peugeot, Renault, Scania, Suzuki, Tata, Tatra, Toyota, Ursus, UTB, Volvo, Yanmar and Zetor, amongst others.

Garima Global also export parts for air-brake compressors like Wabco, Bendix, Knorr, Cummins, Clayton Dewandre, Mercedes, Midland etc.

PRODUCT CATALOG

Garima Global has developed an extensive range of components for engine, braking, transmission, suspension, steering, chassis, electrical, lighting and other automotive sub-systems. To assist our customers with choosing the right product for their requirements we have published comprehensive catalogs with engine / vehicle models, interchange with references of OEMs and other popular aftermarket brands, fitment dimensions and other technical data. We strongly encourage you to contact us with your specific requirements so that we can email you the relevant catalogs, and we look forward to starting a mutually beneficial business relationship with you soon!

TYPES OF CAMSHAFTS

Camshaft design is influenced by the valve train configuration, engine structure, manufacturing processes and functional complexity.

VALVE TRAIN CONFIGURATION

OVERHEAD VALVE (OHV)

The camshaft is located nearer to the crankshaft in the engine block and the lifting action is transferred from the camshaft to the valves through an assembly of tappets / cam followers, push rods and rocker arms. The trend is against this configuration due to lower stiffness of the engine system and more moving parts.

OVERHEAD CAMSHAFT (OHC)

Two main variants of this configuration are Single Overhead Camshaft (SOHC) and Double Overhead Camshaft (DOHC) and in both, the camshaft is located in the cylinder head. Crankshaft powers the camshaft by a timing belt or chain at half its own rotational speed. In this configuration also many different types of assemblies consisting of tappets / cam followers, rocker arms and hydraulic lifters are used to actuate the valves.

CONTACT TYPE

SLIDING CONTACT

Simpler and more primitive technology characterized by the cam lobe sliding on a tappet head, with both surfaces hardened, polished and sometimes crowned to reduce frictional losses and achieve gradual wear-in.

ROLLING CONTACT

Modern engines lean toward the tappet being replaced by a cam follower in which its roller and the cam lobe come in to rolling contact. This reduces drive losses and increases tolerable loading, while improving tribologic characteristics of the interface, increasing life of the mating components.

BEARING TYPE

OPEN BEARINGS

Split cam bearing shells, similar to con rod big end bearings, are used at bearing races which form part of the camshaft.

TUNNEL BEARINGS

Bearing races have a diameter bigger than the maximum lobe height so that the camshaft can be slid through the solid bearing races built into the block or head.

MATERIAL

CAST IRON

GREY CAST IRON

1% Chromium is alloyed in Grade 17 cast iron to create 5-7% free carbides, which is then hardened to 52-56 HRC in lobe area. This material can also be used in Chilled Cast Camshafts where rapid cooling of lobe area creates a matrix of carbide that is extremely scuff resistant.

SPHEROIDAL GRAPHITE IRON

Fiat used SG Iron in 1980s but the disadvantage is it scuffs easily in the bearing area. Can be hardened to 52-58 HRC.

STEEL CAMSHAFT

CARBON STEEL

EN8 and EN9 grades have good through-hardening characteristics and are especially compatible with roller cam followers after induction hardening of lobes.

ALLOY STEEL

EN351 and EN34 can be used with a chilled cast tappet after case hardening.

NITRIDING STEEL

EN40B after nitriding gives similar hardness as a chilled cast camshaft but with superior strength of steel.

CHEMICAL COMPOSITION

ELEMENT EN8
SAE 1040
080M40
1.1186
EN9
SAE 1055
070M55
1.0535
EN351
635M15
EN34
665M17
EN40B
722M24
Carbon (%) 0.35-0.45 0.50-0.60 0.10-0.20 0.14-0.20 0.20-0.28
Silicon (%) 0.05-0.35 0.05-0.35 0.35 MAX 0.10-0.35 0.10-0.35
Manganese (%) 0.60-1.00 0.50-0.80 0.60-1.00 0.35-0.75 0.45-0.70
Phosphorus (%) 0.060 MAX 0.060 MAX - 0.035 MAX 0.035 MAX
Sulphur (%) 0.060 MAX 0.060 MAX - 0.040 MAX 0.040 MAX
Chromium (%) - - 0.40-0.80 - 3.00-3.50
Molybdenum (%) - - 0.08-0.10 0.20-0.30 0.45-0.65
Nickel (%) - - 0.60-1.00 1.50-2.00 -

MANUFACTURING

AutoGRACE® camshafts are manufactured by experienced OEM factories in a wide variety of materials to suit every kind of application.

CAST CAMSHAFT

Nodular (spheroidal graphite) or laminar graphite cast iron camshafts have the ideal tribologic characteristics for sliding and low-load rolling contact. The core area and the bearing journals may be grey cast iron with good machinability while the lobes are hardened by one of the following processes:

INDUCTION HARDENING

Rapidly alternating electrical current is used to heat the material in lobe area above its transformation temperature, and then it is rapidly cooled by quenching, causing a case of martensitic structure to develop on the surface which is extremely tough. The softer core remains unchanged, which makes for a very fatigue resistant component.

CHILLED CASTING

Lobe area is cooled rapidly during casting of the camshaft to create an outer ledeburite structure which is highly wear-resistant in chilled cast camshafts.

For smaller production runs this is the preferred process since upfront investment into forging moulds, setup etc. can be avoided, however, strength is many times a limiting factor in these camshafts.

ASSEMBLED CAMSHAFT

Steel tube is rough forged and then machined. Cam lobes and bearing journals are then slid on to the tube and attached to the tube by shrink-fit, press fit, high-pressure forming or some such process. The lobes may be of steel, or sintered powder metal to achieve highly precise lobe geometry which eliminates the need for any further machining.

STEEL CAMSHAFT

In high load and high speed applications that place great demand on torsional and/or tensile strength of the camshaft, forged steel camshafts are the preferred choice. Costly development of forging dies require high minimum quantities for production runs to be feasible.

REDUCTION OF MASS

To reduce the static mass as well as the rotational inertia of the system, various techniques are used to reduce the mass of the camshaft. Simplest of them is to drill a straight or graduated hole through the central axis of the camshaft which may also be used as part of the lubrication circuit. Integrating bearings into the camshaft core and reducing wall thickness of casting tube are also promising ways to reduce mass.

TESTING

AutoGRACE® camshafts undergo stringent checks at our in-house lab before dispatch to our discerning customers globally on the following important parameters, among others:

  • Material Grade
  • Dimensional Specifications:
    • Cam Lobe Profiles
    • Relative Timing Angles
    • Location of Each Lobe and Journal
    • Timing Mark Location
    • Bearing Journal Diameters
  • Physical Properties
    • Hardness of Lobes
    • Case Depth
    • Hardness vs. Case Depth Profile
    • Surface Finish of Bearing and Lobe Surfaces
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