Machine-Maintenance

Way oil lubricates the machine guide ways and prevents stick-slip motion during slow feed movements. Deep hole drilling machines operate at low feed rates — 0.01-0.10 mm/rev — which makes stick-slip a potential problem. I have dealt with stick-slip on three different machine models and the fix always came back to the right oil selection. Viscosity Selection by Way Type The oil viscosity depends on the way type. Box ways need higher viscosity oil than linear guides. For box ways, I use ISO 150-220 way oil. For linear guides, I use ISO 68-100 way oil. ...

A deep hole drilling machine that is down costs more per hour than almost any other machine in the shop. The hourly burden rate is high, the parts going through it are usually high-value, and the whole production schedule backs up when one machine stops. I have spent years learning what keeps these machines running, and most of what works is not in the maintenance manual. Here is my approach to reliability — what I actually do, not what the textbook says. ...

Deep hole drilling machines need lubrication for the bed ways, ball screws, guide bushings, and spindle bearings. I have worked on machines where poor lubrication caused thousands of dollars in way damage, and I have also seen well-maintained machines hold their original alignment for over a decade. The difference comes down to having the right lubrication system and following a consistent schedule. A deep hole drilling machine faces higher coolant exposure and more abrasive conditions than a standard CNC, so the lubrication demands are more rigorous. ...

Problem Description BTA drilling machines face unique wear challenges that standard gun drilling machines don’t. The coolant and chips flow through the center of the drill tube, so internal abrasion is constant. I’ve cut open BTA drill tubes that had worn through 2 mm of wall thickness over 2,000 hours of operation — hidden damage that would eventually cause a catastrophic tube failure. The support pads on BTA cutting heads also wear in ways that affect bore quality. Worn pads allow the head to chatter, producing a bore with spiral marks that fail surface finish requirements. ...

Seals in a deep hole drilling machine don’t get much attention — until they start leaking. Then they stop production and cost time and money to replace. I’ve dealt with seal failures on both gun drilling and BTA machines. The symptoms range from annoying drips to complete coolant system failure. Where Seals Are Used Deep hole drilling machines have seals at several points: Rotating coolant union. Where the coolant transfers from the stationary supply line to the rotating spindle. This is the most common seal failure point. Drill tube connection. Where the drill tube connects to the spindle. The seal here prevents high-pressure coolant from leaking around the connection. Pressure head. Where the coolant enters the bore at the workpiece entry. The pressure head seal contains the coolant and directs it into the bore. Cylinder seals. On machines with hydraulic feed systems, the cylinder seals keep the hydraulic fluid contained. Each of these seals operates under different conditions — pressure, speed, and temperature vary depending on the location. ...