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Valve Train Parts : Severe/Abnormal Wear at Cam/Tappet

What Happened in Diesel Engines. Valve Train Parts : Severe/Abnormal Wear at Cam/Tappet Power Train Parts : Severe/Abnormal Wear at Piston Ring/liner. Heavy Duty Diesel-Engine Exhaust Gas Regulation. EURO1(1992 ). 70Kg/mm^2.

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Valve Train Parts : Severe/Abnormal Wear at Cam/Tappet

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  1. What Happened in Diesel Engines • Valve Train Parts : Severe/Abnormal Wear at Cam/Tappet • Power Train Parts : Severe/Abnormal Wear at Piston Ring/liner TMC ( TechnoMaterialCorp.)

  2. Heavy Duty Diesel-Engine Exhaust Gas Regulation EURO1(1992) 70Kg/mm^2 • Cam: Induction H Tappet : Chilled Cast • Ring: Cr Plating Liner: High P-Cast Stress: ? • Cam: Induction H Tappet: ? Ceramic • Ring : ? Cr-Diamond Liner: ? Laser Steel 160Kg/mm^2 • Cam: Induction H Tappet: Hard Metal • Ring: Cr-Ceramic Liner: High Alloy Cast EURO2(1996) KOREA(2000) EURO3(2000) KOREA(2004) EURO4(2005) KOREA(2006) It is a Chance of Technologies Advance. TMC ( TechnoMaterialCorp.)

  3. Cam and Tappet Movement in Valve Train System • Contact between Cam and Tappet • Line contact, Rolling with sliding • Crowned surface of tappet (for uniform wear) • Lubrication • Cam Base Area : Hydrodynamic lubrication • Cam Nose Area : Boundarylubrication • # Nose ± 20° , Max. contact stress, Lubrication film failure •  Severe wear occurs • Hertzian Contact Stress • σmax ∝ [P/WR(1/E1+1/E2)]½ • W = Cam width R = Cam radius • P = Max. loadσmax =Max. Contact Stress • E1/E2 = Young’s modulus ofCam/Tappet TMC ( TechnoMaterialCorp.)

  4. Valve Train System, OHV Type Diesel Engine • Valve timing control • Profile of Cam nose will be maintained during engine life • Wear of Cam and Tappet  Timing Changed  Imperfect Burning • PM and NOx increase in exhaust gas • If severe wear occurrs in cam and tappet  Engine Fails TMC ( TechnoMaterialCorp.)

  5. A case of failure - Tappet Pitting and Cam Scuffing • High Hertzian Contact Stress • Adhesion of mating materials TMC ( TechnoMaterialCorp.)

  6. Newly Designed Hard metal tappet - Characteristics I • Simple Process • Low Sintering Temperature for WC Tip (1450 =>1050°C) • Direct Bonding of As-Received WC tip and Machined Body • High Bonding Strength • Vacuum Atmosphere • High Wettability to Steel • Formation of Diffusion Layer - Main composition : WC with Binder Alloy • WC size : Average 1~5m Hardness : Above HRA 85 • Bending strength : Average 100 kgf/mm^2 (TRS) • Young’s modulus : 43,000 kg/mm^2 • Thermal conductivity : 0.17 cal/cm sec C (75W/mK) • Thermal expansion coefficient : 6 x 10-6/ C TMC ( TechnoMaterialCorp.)

  7. Mass Production  Technical Alliance with the T.M.C, High Technology possession enterprise  There’s no Quality Problems in mass production of Hard Metal tappet for 5 years ▶CUSTOMER & SPECIFICATION OF ENGINE ▶ SUPPLY RECORD OF HARD METAL TAPPET(T.M.C) TMC ( TechnoMaterialCorp.)

  8. Wear Test - Scuffing Scuffing occur No Scuffing Line contact, Reciprocal sliding with rolling. Measure the rapid increase time of friction coefficient scuffing time TMC ( TechnoMaterialCorp.)

  9. Wear Test - Results  Hard metal tappet have a longer scuffing time than Fe-alloy tappet  3 of 5 case of hard metal tappet have not scuffing during test Hard metal tappet have a smaller friction coefficient than Fe-alloy tappet Hard metal tappet have a better anti-scuffing characteristics than Fe-alloy tappet TMC ( TechnoMaterialCorp.)

  10. Rig Test(Motoring) - Pitting - Part test of engine, driven by electrical motor - Performed 500 hours, at 2200 crankshaft RPM - Contact stress of cam and tappet is higher than in a real engine - 6 Fe-alloy tappets and 6 hard metal tappets are tested. - Fe alloy Tappets have pitting & all of them have not shown crowned shape - Hard Metal tappets have no pitting & remain crowned shape TMC ( TechnoMaterialCorp.)

  11. Dynamo Test & Field Test To test the Reliability of Engine parts  Engine Dynamo Test : 1,000 hour, 2200 RPM - Fe alloy tappets have pitting (2 of 6) & Not scuffing - Hard metal tappets have no pitting and no scuffing  Field Test : 100,000km - Bus and Truck mounting, Only hard metal tappet test. - No pitting and No scuffing - Crowned shape of tappet is remained. - The surface of Tappet and cam were fine-polished. - It means that it is possible to use the tappets again. - There’s no wear problem after applying in the field for nearly 5 years TMC ( TechnoMaterialCorp.)

  12. Reliability of Tappet Bonding Ultrasonic test of bonded parts  Last 3 years, mass production of Hard Metal tappet, There’s no apart of bonded part .  Quality assurance system of tappet produced, it has a reliabilities TMC ( TechnoMaterialCorp.)

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