Multiquip CDM2CSA - Manual (Page 11)

DM15A9C/CDM2CSA — OPERATION AND PARTS MANUAL — REV. #1 (11/09/05) — PAGE 11
DM15A9C/CDM2CSA — GENERAL INFORMATION
Water
Water acts as a coolant, eliminating the heat caused by the friction
of the drilling. This preserves the integrity of the drill bit. Without
water acting as a coolant, the heat buildup during drilling will greatly
reduce the life cycle of the drill bit.
During drilling water flushes loose, abrasive particles created during
drilling. These particles consist of aggregate, sand, and various
metals from embedded steel. The hole must be free of debris to
allow the core bit to work.
If loose particles are not properly flushed from the hole, an
unecessary drag will occur along the side of the core barrel. This
can contribute to bit glazing (less power) and damage to the electric
motor. In addition loose particles contribute to premature bit wear.
Monitor water flow continuously. Water volume should be adjusted
until water return is muddy. Clear streaks indicate too much water
volume. Excessive water volume is the leading cause of bit glazing.
Excessive water prevents adequate segment material contact. When
the bit segments do not make proper contact with the work surface
(hydro-planing) they begin to glaze. Adequate water volume varies
according to bit diameter. Use only enough water during drilling to
flush particles from the work surface.
Operator Technique
Always drill with consistent uniform pressure. NEVER subject the
drill bit to sudden impacts. Uneven pressure can damage a bit. Slow
bit penetration leads to bit glazing. Excessive drill pressure can
overload the drill motor. Always try and let the drill bit do the work and
try not to force the bit through the material.
If vibration occurs while drilling do the following:
■
Stop drilling
■
Turn motor off
■
Check for loose nuts or bolts on the equipment
■
Check for bit runout. Replace if necessary
Drilling Performance
Factors that influence core drilling:
■
Amount of water flow
■
Condition of equipment
■
RPM of electric drill motor
■
Amount and size steel
■
Age of concrete
■
Aggregate (size, type, hardness, abrasiveness)
■
Operator technique
■
Bit runout
Bit Glazing
Bit binding is caused by either a dull (glazed) bit or a poorly stabilized
drilling rig. The causes of glazing are as follows:
■
Wrong RPM for drill bit diameter
■
Excessive feed pressure
■
Low feed pressure
■
High steel content in material work surface
■
Large hard aggregate
■
Too much water
■
Low electric motor RPM's