Oilite

Oilite is a porous bronze or iron alloy commonly impregnated with an oil lubricant and used in bearings. The original Oilite and Oilite Plus are bronze alloys, while Super Oilite and Super Oilite 16 are iron-based. Oilite was developed by Chrysler in 1930,[1] originally for use in bearings for water pumps and spring shackles, and without oil as the porous filter element in gasoline filters. Chrysler sold approximately 500,000 Oilite bearings in 1930 and approximately 2.5 million the next year. The Super Oilite was introduced in 1932. Overall sales of all Oilite material in 1932 was seven million; this rose to 18 million in 1933. Oilite was a profit center for Chrysler during this time.[1] Currently, the Oilite trademark belongs to Beemer Precision.[2]

Composition

Oilite is formed using powder metallurgy so that tiny pores are present in the metal. The pores are then vacuum impregnated with an oil to improve the materials bearing ability.[3] The material holds approximately 20% oil by volume.[4] The most common lubricant is SAE 30 oil.[5]

Due to the porous structure, machining Oilite poses a special situation. To machine Oilite, the cutting tool must be—and stay—sharp; therefore, tungsten carbide is often used. The sharp tool preserves the open-pore structure, because a dull tool would smear the material and close up the pores that are on the surface adjacent to the journal, which is where the lubrication needs to be. Reaming is not recommended, but can be done with an extremely sharp tool. Honing and grinding should not be performed on any surface that is in contact with the journal as these processes always smear the pores.[3]

Chemical composition of various Oilite grades[3]
Copper [%] Iron [%] Graphite [%] Tin [%] Other elements (max.) [%]
Oilite 87.2–90.5 1 max. 0–0.3 9.5–10.5 1.0
Super Oilite 18–22 Balance - - 2.0
Super Oilite 16 18–22 Balance 0.6–1.0 - 2.0

Types

The different types of Oilite vary by the metal alloy, not by the type of oil with which they are impregnated. Many types of oil can be impregnated to facilitate various applications, such as high and low speed, high and low load, various temperature ranges, food-grade applications, and plastic compatibility.[3]

Oilite

Oilite material is the most widely used of all the types of Oilites. Standards that encompass the Oilite material are: ASTM B-438-95A Grade 1 Type II, MIL-B-5687D Type 1 Grade 1, CT-1000-K26, SAE 841, and old SAE standard Type 1 Class A.[3]

Oilite Plus

Oilite Plus is the same bronze alloy as an Oilite, impregnated with turbine oil and fine particles of polytetrafluoroethylene (PTFE). This reduces the friction by approximately 17% versus standard Oilite material. This material is usually used in applications that exhibit mixed-film or boundary condition lubrication. Situations where this type of lubrication is encountered commonly include oscillating motions, slow speeds, intermittent use, pulsating loads, and uneven loads.[3]

Super Oilite

Super Oilite is an iron based material that is harder, stronger, and cheaper than Oilite. It is rated for slower speeds, but it can handle higher loads. Common applications include farm equipment, winches, sheaves, conveyors, and pulleys. Applicable standards are: ASTM B-439-95 Grade 4, MIL-B-5687D Type 2 Grade 4, SAE 863, and old SAE standard Type 3.[3]

Super Oilite 16 is Super Oilite that has been heat treated to a hardness greater than HRC 50. This material is used for extreme loads and slow oscillating motions. Common applications include cranes, hoists, machine presses, and conveyors. The applicable standard is ASTM B-426 Grade 4 Type 2.[3]

Comparison

Physical and mechanical properties[3]
Oilite Super Oilite Super Oilite 16
Density [g/cm3] 6.4–6.8 5.8–6.2 6.0–6.4
Minimum porosity [% oil by vol.] 19 19 15
Strength constant (K) 26,500 40,000 60,000
Tensile strength [psi] 14,000 22,000 32,000
Elongation [% in 1"] 1 1 0.5
Yield strength in compression [psi] 11,000 22,000 40,000
Maximum bearing limits[3]
Material PV Static P [psi] Dynamic P [psi] V [sfm]
Oilite 50,000 8,000 2,000 1,200
Super Oilite 35,000 20,000 4,000 225
Super Oilite 16 75,000 50,000 8,000 35

References

  1. 1 2 Curcio, Vincent (2001), Chrysler: The Life and Times of an Automotive Genius, Oxford University Press US, p. 485, ISBN 978-0-19-514705-6.
  2. ↑ Oilite bearings, retrieved 2009-12-17.
  3. 1 2 3 4 5 6 7 8 9 10 Oilite, archived from the original (PDF) on 2009-12-17, retrieved 2009-12-17.
  4. ↑ SAE 841, archived from the original (PDF) on 2009-12-17, retrieved 2009-12-17.
  5. ↑ McMaster-Carr catalog (115th ed.), McMaster-Carr, p. 1116, retrieved 2009-12-17.
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