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AutoGRACE®
Engine Valves

Trustworthy Gatekeepers of the Engine

Over the life of an average engine, valves will open and close 300 million times, which places heavy demand on the fatigue strength and reliability of the valves.

Product

Over the life of an average engine, valves will open and close 300 million times, which places heavy demand on the fatigue strength and reliability of the valves.

PRODUCT RANGE

Garima Global is one of the few companies specialized in developing custom
made engine valves as per the requirements of our highly demanding customers.

Size Range of Engine Valves in AutoGRACE® Brand

SPECIFICATION FROM TO
Stem Dia (mm) 4.5 45
Head Dia (mm) 15 250
Total Length (mm) 50 1000

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 Engine Valves

Fundamentally engine valves may be classified based on their function, design and material.

FUNCTION

INLET VALVES (IN)

Control the flow of incoming air+fuel mix (gasoline engines) / air (diesel engines) into the power cylinder. Not subjected to extreme thermal loads due to cooling effect of incoming gases. Are usually larger in diameter than exhaust valves to allow more air to enter the combustion chamber, and also because the fluids passing through them are at a lower pressure.

EXHAUST VALVES (EX)

Let the post-combustion exhaust gases out of the power cylinder, hence are subject to extreme thermal loads and corrosive chemicals. Are usually smaller than inlet valves since the gases are under high pressure and hence do not need as large an opening to escape out of the engine. However, they tend to be made of more expensive materials like non-magnetic steels, or coatings to harden their seating face to cope with their more demanding function.

DESIGN

VALVE STEM

SOLID STEM

Most valves have a solid monometallic or bi-metallic stem of steel grades mentioned in the MATERIALS section below, depending on their function and application.

HOLLOW STEM

Mostly bi-metallic with stem of EN52 and head of 21-4N grade steels, but there exist mono-metallic versions too. The stem is hollowed out to about 60% of the outer diameter, to reduce weight, and filled with liquid sodium which is agitated inside the stem cavity due to the rapid reciprocating motion of the valve. This conducts heat away from the head toward the stem. Used mostly in high-performance engines because of the extra cost involved in manufacturing.

The valve stem has a slight taper on the outer diameter to counter the temperature gradient during operation and prevent valve sticking. To avoid excess heat from reaching the valve stem seals, the stem cavity is terminated at least 10 mm away from the stem tip. Variants, in increasing order of performance and manufacturing complexity are:

TUBE ON SOLID METAL

Head is drilled from stem end and friction welded to a solid stem which is made of a hardenable alloy.

CLOSED-OFF

Similar to the above type, but the bore is closed off by inductive heating and forging.

HOLLOW VALVE

Drilled from head end to reduce weight even further by hollowing out a larger portion of the head. The cavity is then sealed using a capping plate and a special process.

MATERIAL

MONOMETALLIC VALVES

Ferritic-Martensitic steels like EN52 / X45CrSi93 are cost effective and sufficient for inlet valves and monometallic exhaust valves used in slower, low-performance engines. X85CrMoV18-2 is used for intake valves of higher performance engines where thermal / mechanical loads may not permit Cr-Si material. For intake valves, wear resistance is more important than thermal or corrosion resistance, hence martensitic steels are appropriate for them.

BI-METALLIC VALVES

Non-magnetic Austenitic Cr-Mn steels like X53CrMnNiN21-9 (21-4N) are the cost effective choice for the valve head, which is welded to a stem made of X45CrSi93 or X85CrMoV18-2 steel. Ni-based Superalloys like INCONEL®-751 and NIMONIC®-80A are used where Cr-Mn steels cannot satisfy the operational reliability required, for example, in racing, aviation and heavily turbocharged diesel engines. Martensitic stem can be hardened to withstand the fatigue load on the tip of the valve while the austenitic or superalloy head portion has high thermal and corrosion resistance.

CHEMICAL COMPOSITION

ELEMENT X45CrSi93
X45CrSi3
X50Cr9Si93
1.4718
EN52
HNV3
SUH 1
X85CrMoV18-2
1.4748
X53CrMnNiN21-9
X55Cr22Mn9Ni4N
1.4871
21-4N
EV8
SUH 35
INCONEL®-751 NOMONIC®-80A
Carbon (%) 0.40-0.50 0.80-0.90 0.48-0.58 0.10 MAX 0.10 MAX
Silicon (%) 2.75-3.75 1.00 MAX 0.25 0.50 MAX 1.00 MAX
Manganese (%) 0.80 MAX 1.50 MAX 8.00-10.00 1.00 MAX 1.00 MAX
Phosphorus (%) 0.040 MAX 0.040 MAX 0.050 MAX - -
Sulphur (%) 0.030 MAX 0.030 MAX 0.030 MAX 0.01 MAX 0.015 MAX
Chromium (%) 7.50-9.50 16.50-18.50 20.00-22.00 14.00-17.00 18.00-21.00
Molybdenum (%) - 2.00-2.50 - - -
Nickel (%) 0.50 MAX - 3.25-4.50 (+Co) 70.0 MIN BAL
Nitrogen (%) - - 0.35-0.50 - -
Vanadium (%) - 0.30-0.60 - - -
Iron (%) - - - 5.00-9.00 3.00 MAX
Titanium (%) - - - 2.00-2.60 1.80-2.70
Aluminum (%) - - - 0.90-1.50 1.00-1.80
Niobium +
Tantalum (%)
- - - 0.70-1.20 -
Copper (%) - - - 0.50 MAX 0.20 MAX
Cobalt (%) - - - - 2.00 MAX
Boron (%) - - - - 0.008 MAX
Zirconium (%) - - - - 0.15 MAX

Other frequently used valve materials:

  • X40Cr11Si2Mo1 / 1.4731 / X40CrSiMo102 / SUH 3
  • X55Cr21Mn8Ni2N / 1.4875 / X55CrMnNiN208 / 21-2N / EV12
  • X20Cr21Ni12N / 21-12N / EV4 / SUH 37
  • X33CrNiMnN238 / 1.4866 / 23-8N / EV16
  • X50CrMnNiNbN219 / 1.4882 / 21-43

MANUFACTURING

AutoGRACE® valves are manufactured by leading OEM and OES manufacturers across India that adhere to the highest quality specifications. In general the process involves first manufacturing the blank which is then precisely machined to obtain the fitment and functional tolerances. Lastly, special coatings may be applied to increases resistance to wear, corrosion, fatigue etc.

BLANKS

Engine valve blanks may be manufactured by the following processes.

UPSETTING

A round bar of diameter slightly bigger than the finished stem diameter is heated and then reformed at one end to form a pear-shaped lump that is then machined into the head of the valve. This is the preferred and most cost effective method of valve production due to minimal wastage of material.

HOT EXTRUSION

A round bar of diameter 2/3 of the final head diameter is heated and reformed to make a blank in two forging steps. The length of the bar has to be calculated according to the desired volume of the blank.

FRCITION WELDING

The valve head is formed by either of the above processes using a higher grade of austenitic steel which is then friction welded to a stem, which is simply a round bar, of lower grade but cost effective martensitic steel, thus achieving the ideal combination of materials required for stem and head in a single valve.

HEAT TREATMENT

MARTENSITIC STEELS

These steels loose strength and hardness at elevated temperatures but can be hardened to 35-55 HRC, hence are the material of choice for the stem because the tip of the stem needs to be fatigue and wear resistant against the constant tapping of the valve tappet.

AUSTENITIC STEELS

These steels are resistant to thermal loads and corrosion but not very hardenable. Limited efficacy in seat hardening may be achieved by a closely controlled processes. Please see topics of interest below to see the details of heat treatment processes.

INDUCTION HARDENING

Zones prone to wear, like the tip of the stem and the seat of the head are induction hardened. Valve keeper grooves may also be case hardened or through hardened.

MACHINING

AutoGRACE® engine valves are manufactured on completely robotized lines especially for large production runs by leading manufacturers of engine valves in India. For smaller production runs the valves are sourced from semi-automated manufacturers who follow stringent quality systems like IATF or ISO and can provide the most cost effective solutions at adequate quality levels.

A combination of CNC machines, Special Purpose Machines (SPMs), Upsetters, Material Handling Robots, Centerless Grinders, Automatic Seat Grinders, Forging Lines, Induction Heaters and Surface Coating Plants all available in-house are used to produce these highly precise engine components.

SURFACE TREATMENTS

CHROME PLATING

Stem of the valve that reciprocates inside the guide is chrome plated to make it wear resistant. Plating is 3-15 μm thick.

NITRIDING

Nitrogen is diffused into the surface of the valve, forming a highly wear resistant layer of iron-nitride 10-30 μm thick. Since this is not a plating but rather a diffusion process, there is no risk of the protective layer being stripped away due to scuffing or abrasion.

PROJECTION TIP WELDING / BUTTON WELDING

A wafer of hardened, wear-resistant tip is welded onto the valve. This is similar to a bimetallic valve but the hardenable martensitic tip is much smaller in length than a typical bimetal valve.

HARD FACING / STELLITING

In especially heavy duty or high performance engines, a groove is machined into the tip or the seating ring of the valve. Stellite™ is then deposited into this groove which is then machined to achieve the required shape / dimensions. Stellite™ is a non-magnetic cobalt alloy that retains wear resistance and hardness even at elevated temperatures. Popular grades of Stellite™ suitable for valves are mentioned below:

CHEMICAL COMPOSITION

ELEMENT STELLITE™ 1
R30001
(SF)A 5.21
ERCoCR-C
STELLITE™ 6
R30006
(SF)A 5.21
ERCoCR-A
STELLITE™ 12
R30012
(SF)A 5.21
ERCoCR-B
Cobalt (%) BAL BAL BAL
Chromium (%) 32 30 30
Tungsten (%) 12 4-5 8
Carbon (%) 2.45 1.2 1.55
Nickel (%) 3.0 MAX 3.0 MAX 3.0 MAX
Molybdenum (%) 1.0 MAX 1.0 MAX 1.0 MAX
Iron (%) 3.0 MAX 3.0 MAX 3.0 MAX
Silicon (%) 2.0 MAX 2.0 MAX 2.0 MAX
HARDNESS (HRC) 51-56 40-45 46-51

Post any surface treatment grinding process is used to achieve surface finish (Ra < 0.2 on stem) by polishing the chrome nodules or nitride needles off the surface.

TESTING

AutoGRACE® engine valves undergo stringent checks at our in-house lab before dispatch to our discerning customers globally on the following important parameters, among others. Garima Global has in-house Mitutoyo® Roundness Tester and Contracer to test all critical geometrical parameters of the valves. Our lab is also equipped with spectrometer, microscope, hardness tester, surface roughness tester etc. to rest the material and surface characteristics of these components.

  • Material Grade
    • Crack Detection
  • Physical Properties
    • Weld Strength
    • Tensile Strength
    • Bending Strength
  • Dimensional Specifications:
    • Stem Diameter
      • Roundness
      • Taper
      • Cylindricity
    • Valve Head
      • Seat Angle
      • Head Diameter
    • Valve Fitment
      • Valve Seat to Valve Cotter Groove Length
      • Total Length
      • Cotter Groove Profile
      • Head-Stem Transition Profile
      • Seat Profile
      • Concentricity Between Seating Ring and Stem Shaft
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