The ASTM G77 test determines the resistance of materials to metal-to-metal sliding wear. Utilizing a block-on-ring testing machine to rank pairs of materials according to their sliding-wear compatibility characteristics, this test replicates “adhesive, metal-to-metal” wear. Results are reported as volume loss in cubic millimeters for both the block and the ring. Materials of higher wear resistance have lower volume loss. Friction coefficents may also be established during this test.
Test Conditions
Tested on 3000 meter slide length. Fixed load and stepped load to COF seizure. Mineral oil lubricant used, 30,000 revolutions, 300 RPM and 300 POUNDS FORCE
Adhesive Wear
Adhesive wear occurs when surface asperities on two materials contact under load, which converts relatively low force into super high pressure. Friction results between two points, creating micro-welds (adhesion) that subsequently fracture and cause undesirable fragments that impart abrasive wear to the two mating surfaces.
| Stationary Block | Block Loss | Ring Loss | Rotating Ring |
|---|---|---|---|
| BiMetallic (FeCr) | 0.1370 | 0.2200 | C1000 |
| BiMetallic (FeCr) | 0.1624 | 0.5158 | Moly |
| BiMetallic (FeCr) | 0.1990 | 1.4000 | C4000 |
| BiMetallic (FeCr) | 0.4000 | 3.7000 | Stellite |
| BiMetallic (FeCr) | 0.1995 | 4.7000 | Colmony 56 |
| Carbide (WC) | 0.0207 | 0.0641 | C1000 |
| Carbide (WC) | 0.0249 | 0.2000 | C4000 |
| Carbide (WC) | 0.1127 | 0.2966 | CPM-9V |
| Nitrided Steel | 0.045 | 0.0836 | C1000 |
| Nitrided Steel | 0.605 | 1.192 | Nitrided Steel |
Note: This test was mainly done to compare a misconception that a hard coated feedscrew (Ring) in contact with a softer barrel liner (Block) will cause premature wear to the barrel. This test clearly shows that our tungsten coatings do not wear a barrel faster than any other alloys commonly used for wear resistance and actually can increase the barrel life.