A basic, but important, tip is to “Keep it Clean”. Even the smallest foreign particle can cause untold damage to the Hammer.
“World Class” DTH Tools need tight tolerances between the piston and the internal running surfaces for speed and efficiency. Dirt or other foreign bodies passing through can become trapped between the outer wall of the piston and the internal bore of the cylinder.
When this happens, with the piston striking the bit at over 30 times per second, intense heat can be generated and minute cracks can begin to develop from the surface and travel inwardly to cause piston failure.
The tell-tail blue heat spots often seen on the surface of the piston affected by contamination, indicates that at some point the zone has been subjected to temperatures in excess of 600 centigrade. And whilst insufficient lubrication will cause heat zones to form, contamination is also a major contributor.
A further problem can occur when debris becomes trapped between the piston and the drill bit. Damage can be caused to the inter-face surface of the piston and bit anvil with the risk of face distortion and crack propagation.
If a new bit is fitted to a Hammer with a damaged piston face or alternatively, if a bit with a damaged anvil is fitted to an undamaged piston then cross damage will result at a very early stage. |
