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282 CAM DESIGN HANDBOOK

sandths of an inch thick, Rockwell 65-70. AISI 8620 (inherent core hardness of 35 Rock-
well C) is an oil-quench material that is sometimes carburized.
• Spherical, curved, or flat-faced followers with pure sliding have adhesive wear action.
• Offsetting the mushroom follower gives a corkscrew motion to the follower and dis-
tributes wear.
• Surface quality after machining is almost always changed by the destructive action of
metal removal, especially in grinding. In general, surface destruction is related to the
pressure and the speed of the metal-finishing operation and the metal being affected to
an appreciable distance below the surface. The effects on the surface are high stresses
due to cold working, higher susceptibility to corrosive action, and metallurgical change
due to high cutting temperatures.
• Cleanliness of the oil lubricant system is critical.
• Shot peening of steel cams increases their fatigue life by 50 percent.

REFERENCES

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York, 1980.
Godfrey, D., “Boundary Lubrication,” Interdisciplinary Approach to Friction and Wear, pp. 335–84,
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Graham, J.D., “Pitting of Gear Teeth,” Handbook of Mechanical Wear, pp. 138, 143, C. Lipson, Ed.,
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dhubbard@peaonet.com, 2000.
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between Bodies with Applications,” Ing. Vetunsk Akad. Handl., 116, 1932.
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