Inserts
Deep Hole Drill Cutting Tips
Deep Hole Drill Cutting Tips
A deep hole job requires a combination of care and specialized tools.deep hole drill cutting tips Editor Chris Felix sat down with Cory DeLuca, CEO of Allied Specialty Tools, to learn his tips for handling the biggest challenges to successful holemaking. He outlines a number of ways to address issues like runout, drill walking, chip control and tool selection.
On the subject of runout: The longer a tool is, the more it has to do to maintain its accuracy. This is particularly true for deep hole drilling where the length of a twist drill is far greater than its diameter. A cautious approach, offline presetting and attention to coolant will go a long way to preserving accuracy and tool life.
Regarding the issue of drill walking: Because of their rotating nature, a tool’s natural reaction to meeting a workpiece is to slide across it rather than dig into it. This is called “walking” and can cause unintended markings on the part or even breakage of the drill. A clean perpendicular entry point, sharp cutting edges and careful use of center drilling will help minimize walking in any deep hole operation.
Choosing the Right Drill
Twist drills can get about 5 x diameter deep without issue. For holes deeper than that, peck drilling becomes a necessity. Using the G-Wizard Calculator, you can automatically determine when pecking should be used. Additionally, if you’re planning on going much deeper than 7 x your diameter, a parabolic flute drill can help with chip extraction. For holes 10 x or more, you’ll want to use a custom G-code cycle that changes the pecking strategy as the hole gets deeper.
Finally, you’ll also want to use a through spindle coolant system with high pressure coolant delivered right to the tip of the drill. This will blast chips up and out of the hole versus letting them fall back inside the hole. This will really aid in getting your holes straight, especially once they’re more than 20 diameters deep. In some cases, gun drilling is necessary, but this is generally only required if the hole needs to be much longer than the drill’s diameter. Otherwise, there are some alternative methods that can be used to make a long straight hole like laser or EDM. Those processes will require additional discussion though.
0users like this.
