| Material Hardness |
Net Result to Performance |
| Harder Material |
Drilling Speed:
Slower |
Bit Life:
Longer |
Reasons for Performance Change:
Harder materials are less abrasive. They are cut into small, fine particles that don't wear the matrix. Since new diamonds aren't exposed, coring speed goes down and bit life goes up. |
| Softer Material |
Drilling Speed:
Faster |
Bit Life:
Shorter |
Reasons for Performance Change:
Softer materials get ripped apart by the diamonds. Those edges are larger and coarser getting through the material quicker, but shortening bit life. |
|
| Aggregate Size |
Net Result to Performance |
| Smaller Aggregate |
Drilling Speed:
Faster |
Bit Life:
Shorter |
Reasons for Performance Change:
Aggregate is denser than concrete. Small pieces take less time to core through. Bit life is shorter because the aggregate chips off into sharp edges, the matrix drops the diamonds. |
| Larger Aggregate |
Drilling Speed:
Slower |
Bit Life:
Longer |
Reasons for Performance Change:
Large aggregate takes longer to core through, bits last longer because the cuttings from the aggregate come off in smaller, finer pieces causing less matrix wear. |
|
| Material Abrasiveness |
Net Result to Performance |
| More Abrasive |
Drilling Speed:
Faster |
Bit Life:
Shorter |
Reasons for Performance Change:
Abrasiveness causes matrix wear. This exposes more diamonds that may fall from the matrix before they wear out. |
| Less Abrasive |
Drilling Speed:
Slower |
Bit Life:
Longer |
Reasons for Performance Change:
Lack of abrasiveness retards matrix wear, fewer new diamonds are exposed. The bit lasts longer but cuts slower. |
|
| Embedded Steel |
Net Result to Performance |
| Light Steel |
Drilling Speed:
Faster |
Bit Life:
Longer |
Reasons for Performance Change:
Cutting through steel which is very tough and dense compared to concrete wears a bit very quickly. Decreasing the amount of steel improves cutting. |
| Heavy Steel |
Drilling Speed:
Slower |
Bit Life:
Shorter |
Reasons for Performance Change:
To cut heavy steel reinforcement you can increase pressure and/or RPMs. Alternately you can decrease water flow or add sharp silica sand into the hole. All decrease bit life. |
|
| Matrix Hardness |
Net Result to Performance |
| Harder Matrix |
Drilling Speed:
Faster |
Bit Life:
Longer |
Reasons for Performance Change:
A harder matrix slows the controlled erosion of exposing new diamonds. |
| Softer Matrix |
Drilling Speed:
Slower |
Bit Life:
Shorter |
Reasons for Performance Change:
Bit life decreases because of faster matrix erosion. Diamonds fall out before they wear out. |
|
| Water Volume |
Net Result to Performance |
| Less Water Flow |
Drilling Speed:
Faster |
Bit Life:
Shorter |
Reasons for Performance Change:
Causes the cuttings to remain in the hole; this exposes more diamonds giving a faster coring speed, but shorter life. |
| More Water Flow |
Drilling Speed:
Slower |
Bit Life:
Longer |
Reasons for Performance Change:
Too much water retards matrix erosion and may lead to bit glazing. |
|
| Motor Speed (RPM) |
Net Result to Performance |
| Lower Motor Speed |
Drilling Speed:
Faster |
Bit Life:
Shorter |
Reasons for Performance Change:
Cuttings/slurry not cleared from hole. The cuttings expose new diamond edges that cut fast and wear fast. The diamonds are in contact with the concrete longer so they cut faster. |
| Higher Motor Speed |
Drilling Speed:
Slower |
Bit Life:
Longer |
Reasons for Performance Change:
The matrix becomes glazed with higher than recommended RPMs, thus affecting cutting speed. Less contact time with the concrete decreases cutting. |
|
| Bit Feed Rate (Pressure) |
Net Result to Performance |
| Lower Feed Rate |
Drilling Speed:
Slower |
Bit Life:
Longer |
Reasons for Performance Change:
Low pressure allows the bit to glaze. Bit life goes up, performance goes down. |
| Higher Feed Rate |
Drilling Speed:
Faster |
Bit Life:
Shorter |
Reasons for Performance Change:
High pressure exposes new cutting edges that cut faster but the diamonds may fall out before they wear out. Excessive pressure may cause the crown to collapse. |
