Oilite

Oilite is a bronze or iron alloy impregnated with an oil lubricant commonly used in bearing applications. The original Oilite and Oilite Plus are bronze alloys, but the related bearing alloys Super Oilite and Super Oilite 16 are iron based. The name is trademarked by Beemer Precision.^[1]

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.^[2] The material holds approximately 20% oil by volume.^[3] The most common lubricant is SAE 30 oil.^[4]

Due to the porous structure, machining Oilite poses a special situation. To machine Oilite, the cutting tool must be sharp 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 a dead 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.^[2]

Chemical composition of various Oilite grades^[2]

	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 types of Oilite list below pertain to the material and not the impregnated oil. Many types of oil are impregnated to facilitate various applications, such as high and low speed, high and low load, various temperature ranges, U.S. Food and Drug Administration (FDA) compliance, and plastic compatibility.^[2]

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.^[2]

Oilite Plus

Oilite Plus is the same bronze alloy as an Oilite, the difference is that it is impregnated with turbine oil and fine particles of polytetrafluoroethylene (PTFE). This reduces the friction by approximately 17% over 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.^[2]

Super Oilite

Super Oilite is an iron based material that is harder, stronger, and cheaper than Oilite. The disadvantage is that 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-438-95 Grade 4, MIL-B-5687D Type 2 Grade 4, SAE 863, and old SAE standard Type 3.^[2]

Super Oilite 16 is just a 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.^[2]

Comparison

Physical and mechanical properties^[2]

	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[disambiguation needed ] (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^[2]

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

History

The Oilite bearing was developed by Chrysler in 1930.^[5] It was originally used in water pumps, spring shackles, and fuel filters. Chrysler sold approximately a half million 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 and 18 million in 1933. Oilite was a profit center for Chrysler during this time.^[5]

References

1. ^ Oilite bearings, http://www.beemerprecision.com/, retrieved 2009-12-17. 
2. ^ ^{a b c d e f g h i j} Oilite, archived from the original on 2009-12-17, http://www.webcitation.org/5m6Ehu7uf, retrieved 2009-12-17. 
3. ^ SAE 841, archived from the original on 2009-12-17, http://www.webcitation.org/5m66FprSI, retrieved 2009-12-17. 
4. ^ McMaster-Carr catalog (115th ed.), McMaster-Carr, p. 1116, http://www.mcmaster.com/#catalog/115/1116, retrieved 2009-12-17. 
5. ^ ^{a b} Curcio, Vincent (2001), Chrysler: The Life and Times of an Automotive Genius, Oxford University Press US, p. 485, ISBN 9780195147056, http://books.google.com/books?id=dt0uwGwuxPgC&pg=PA485.