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Definition: Penetration refers to the depth, in units of 0.1 mm, that a standard cone freely falls and penetrates into grease contained in a standard cup within 5 seconds. Penetration indicates the consistency or the degree of softness/hardness of the grease.
Standard Cone Sizes for Penetration Testing:
- Full-size cone penetration
- 1/2 cone penetration
- 1/4 cone penetration
Conversion Formulas:
a. Conversion of 1/4 cone penetration to full-size cone penetration:
P full-size cone penetration=3.75 * P1/4 cone penetration+24
b. Conversion of 1/2 cone penetration to full-size cone penetration:
P full-size cone penetration=2 * P1/2 cone penetration+5
1. Temperature Influence:
- As temperature increases, penetration increases.
- As temperature decreases, penetration decreases.
The greater the penetration, the softer the grease. Conversely, smaller penetration indicates harder grease.
2. Selection Guidelines:
- For surfaces with high loads, choose grease with smaller penetration.
- For surfaces with low loads, choose grease with larger penetration.
Ø Test Standard: GB/T 269 “Test Method for Penetration of Lubricating Grease and Petroleum Grease”, Equivalent Method: ASTM-D217
