Piston manufacturing process

Piston manufacturing process

1. PISTON MANUFACTURING PROCESS PRESENTED BY, KOWSHIGAN S V

2. Pistons The piston's primary responsibility is to take thermal energy created by the ignition of fuel and air, and transform it into linear motion. Linear motion acts on the crankshaft journal and becomes rotary motion.

3. A typical piston illustrating the various parts and the names.

4. Piston Heads (Crown) Domed Flat Top Recessed (valve reliefs) Dished

5. A domed piston with valve reliefs or valve pockets. A Flat Top piston A Flat Top piston with valve reliefs or valve pockets. A Dished piston with valve reliefs or valve pockets.

6. Piston Skirts Moly Graphite A low-friction moly coating on the skirt of this piston helps prevent piston scuffing when the engine is cold.

7. Piston Composition @ Process

8. Piston Composition @ Process Aluminum - cast Pour aluminum into a mold Light-weight economical Some silicone added General usage Brittle Somewhat unpredictable expansion qualities

9. Piston Composition @ Process

10. Aluminum - Forged Can be made lighter weight (smaller) than cast because it’s stronger Can withstand abuse Newer designs have predictable expansion qualities Silicon & Nickel added Greater piston to wall clearance

11. Notice the temperature difference between a forged piston and a cast piston.

12. Piston diameter being measured using a micrometer.

13. Compression Ring Composition Pearlitic Nodular Iron Ductile Iron – flexible Cast Iron Chromium - .0004” - durable Molybdenum – reduced scuffing Chrome-moly

14. Piston Rings Compression Oil – usually unidirectional Ring expander

15. The preferred material for compression rings is a low-alloyed, heat-treated nodular cast iron (KV1/GOE 52). This material is characterized by a high bending strength of min. 1300 MPa and a high modulus of elasticity attributable to a martensitic microstructure and spherulitic graphite structure .

16. In the 2nd groove, alloyed grey cast iron s are used in a heat-treated condition. Besides having a high bending strength and modulus of elasticity , an increased hardness of 320 to 470 HB is produced in order to obtain the required wear resistance in the uncoated condition. The demand for high wear strength is also met by the use of a tempered, alloyed cast iron (GOE 44). This has the benefit of a high bending strength of min. 800 MPa and high modulus of elasticity . The good wear resistance results from the combination of a fine- pearlitic matrix structure and finely dispersed, precipitated secondary carbides. Unalloyed grey cast iron is used for 2-piece oil rings in the 3rd groove. These ring materials (STD / GOE 12, GOE 13) are characterized by a fine-lamellar graphite structure in a pearlitic matrix and have good conformability due to a relatively low modulus of elasticity .

17. Reduced width piston rings in gasoline engines to match reduction s in the overall height of pistons, and increasing combustion pressures in diesel engines call for materials with increased strength characteristics. These challenges are met by the use of high- chromium alloyed steels and spring steel s. The greater durability under increased stresses is demonstrated by the improved fatigue strength manifested as form stability in a comparison of S/N curves for different piston ring materials ( spherulitic , heat-treated cast iron versus heat-treated 18% chromium steel ). The wear resistance derives from finely distributed chromium carbides of the type M 23 C 6 and M 7 C 3 embedded in the tempered martensite matrix. For improved wear resistance these steels are mainly used in a nitrided condition or with a peripheral coating . The steels mentioned are used chiefly as compression ring materials for gasoline engines and truck diesel engines as well as for the steel rails and expander-spacers of oil control rings and for 2-piece profiled steel oil ring s.

18. Pearlitic Rings Pearlite is a two-phased, lamellar (or layered) structure composed of alternating layers of alpha-ferrite (88 wt%) and cementite (12%) that occurs in some steels and cast irons. The eutectoid composition of Austenite is approximately 0.8% carbon ; steel with less carbon content will contain a corresponding proportion of relatively pure ferrite crystallites that do not participate in the eutectoid reaction and cannot transform into pearlite . The appearance of pearlite under the microscope resembles mother of pearl (also a lamellar structure), from which it takes its name.

19. Nodular (ductile) Iron Ductile iron , also called ductile cast iron , spheroidal graphite iron , nodular cast iron , is a type of cast iron invented in 1943 by Keith Millis. While most varieties of cast iron are brittle, ductile iron is much more flexible and elastic, due to its nodular graphite inclusions.

20. Chromium rings Chromium is a steely-gray, lustrous , hard metal that takes a high polish and has a high melting point. It is odourless, tasteless, and malleable.

21. Chromium facing can be seen on the right side of the sectional view of the piston ring.

22. Molybdenum Rings Molybdenum It has the sixth-highest melting point of any element, and for this reason it is often used in high-strength steel alloys. Molybdenum was discovered in 1778 by Carl Wilhelm Scheele and first isolated in 1781 by Peter Jacob Hjelm

23. Molybdenum facing can be seen on the right side of the sectional view of the piston ring. TECH TIP

24. This typical three-piece oil control ring uses a hump-type stainless steel spacer-expander. The expander separates the two steel rails and presses them against the cylinder wall.

25. Ring Gaps Ring gap must be checked prior to engine assembly Loose Tight Butt gap Gapless?

26. The gapless ring overlaps, while the conventional ring design uses a gap. Frequently Asked Question

27. Gapless Ring

28. Combustion chamber pressure forces the ring against the cylinder wall and the bottom of the ring groove. These are the two sealing surfaces that the top ring must be able to seal for maximum engine power.

29. The piston rings must have the specified side and back clearance. Fitting Piston Rings

30. The rectangular and the barrel face are the most commonly used top compression rings because they provide the best seal.

31. The taper face ring provides good oil control by scraping the cylinder wall. If this design ring were accidentally installed upside down, the tapered face would pump oil into the combustion chamber.

32. Torsional twist rings provide better compression sealing and oil control than regular taper face rings.

33. Cutting Rings

34. Cylinder liner A cylinder liner is a cylindrical part to be fitted into an engine block to form a cylinder. It is one of the most important functional parts to make up the interior of an engine. This is called Cylinder liner in Japan, but some countries (or companies) call this Cylinder sleeve. These are main functions of Cylinder Liners.

35. Properties of an cylinder liner The cylinder liner, serving as the inner wall of a cylinder, forms a sliding surface for the piston rings while retaining the lubricant within. The most important function of cylinder liners is the excellent characteristic as sliding surface and these four necessary points. High anti-galling properties Less wear on the cylinder liner itself Less wear on the partner piston ring Less consumption of lubricant

36. Cylinder liners manufacturing process Centrifugal casting or rotocasting is a casting technique that is typically used to cast thin-walled cylinders. It is used to cast such materials as metal, glass, and concrete. It is noted for the high quality of the results attainable, particularly for precise control of their metallurgy and crystal structure. Unlike most other casting techniques, centrifugal casting is chiefly used to manufacture stock materials in standard sizes for further machining, rather than shaped parts tailored to a particular end-use.

37. Materials which can be casted in centrifugal casting Typical materials that can be cast with this process are iron, steel, stainless steels, glass, and alloys of aluminum , copper and nickel. Two materials can be cast together by introducing a second material during the process.

38. Applications of centrifugal castings Concrete pipe and form Typical parts made by this process are pipes, flywheels, cylinder liners and other parts that are axi -symmetric. It is notably used to cast cylinder liners and sleeve valves for piston engines, parts which could not be reliably manufactured otherwise.