Diamond Core Drill Facts

In the past there were only a few machines capable of quality drilling small holes (under 1/8 inch or 3.18 mm). Then CNC milling centers were developed  that are capable of drilling holes down to .025 inch with coolant moving through the drill center. With the manual machines we had always recommended drilling by the pecking method, where the operator constantly lowers and raises the drill to ensure a steady supply of coolant at the cutting point. Now, with the automatic CNC machines, we can drill straight through the workpiece. The operation is faster and the drill lasts longer. This only applies to core drills, because it is still necessary to use the pecking method with solid drills

Equipment For Diamond Core Drills
When the goal is to drill chip-free holes consistently, every component in the drilling process is important. The basic equipment required is a sturdy, vibration-free and well-made machine, capable of developing the proper speeds and, at the same time, allowing sensitive feeds. The machine must be mounted on a firm base and its spindle must be periodically checked for run out.. The workpiece should be securely held in position. Moreover, the spindle bearings must be in good condition and the feed sensitive enough for precision down feeds.

Diamond Grit For Diamond Core Drills
Diamond grit is available in sizes ranging from a coarse 20/30 to a fine 270/320 grit. Choice of grit size is largely determined by the size of the drill and the material being drilled. It is highly important that the correct grit size be used. A coarse 20/30 grit diamond grill will not give the same performances as a 150 grit drill. Generally speaking, coarser grit sizes are used for faster stock removal (i.e. Higher productivity) without much concern for surface finish.

Coolant For Diamond Core Drills
Coolant is as important as the drill bit itself. We do not recommend drilling dry with diamond core drills.  Coolant serves two purposes: first to keep drill and material cool; and second, to flush away abraded particles that could otherwise impede the operation of the drill.  With the use of an additive, coolant flow is increased, thus aiding in carrying away the abraded material.  The ideal procedure is to supply coolant under controlled pressure through the center of the drill. With solid drills, an abundant flow of pressurized coolant to the outside is good. As a rule of thumb, we recommend a pressure of 120 psi for a 0.027 core drill. For a 1 inch drill, 50-60 psi is adequate.  For production purposes a CNC milling center with through the spindle coolant would be preferred.