Estimating cycle time for deep hole drilling is straightforward if you break it into parts. I have been quoting jobs for over a decade, and the formula below has served me well across gun drilling, BTA, and ejector drilling. The total cycle time determines whether a job is profitable. Miss it by 20% and you either lose the quote or lose money on every part. Here is how I calculate it. ...
Here’s how a deep hole drilling machine works, from my experience running them. A deep hole drilling machine is a specialized machine tool designed to drill holes with high depth-to-diameter ratios. The working principle is straightforward, but the details matter. I’ve operated these machines for over a decade, and while the control systems have gotten smarter, the mechanical fundamentals haven’t changed at all. I’ve trained over 40 operators on deep hole drilling machines and the most common mistake is underestimating the importance of coolant pressure. ...
I use deep hole drilling when the L/D ratio exceeds 10:1 — that is the threshold where conventional twist drilling stops being reliable and specialized deep hole drilling takes over. But the decision involves more than just the depth-to-diameter ratio. I have run both processes side by side on hundreds of jobs, and the differences in surface finish, straightness, cycle time, and tool cost dictate which approach makes sense for each part. ...
Gun drilling is a machining process for drilling deep holes with high straightness and good surface finish. It’s the method of choice when a hole needs to be deeper than a conventional twist drill can reach. The process gets its name from its original application: drilling gun barrels. The same principles used to drill a 5mm hole through 2 meters of steel for a rifle barrel are used today to drill cooling channels in injection molds, oil passages in crankshafts, and bores in hydraulic cylinders. ...