Hydraulic cylinder drift on deep hole drilling machines causes the feed axis to move when it should stay in position. This drift can advance the drill into the bore when it should be retracting, causing tool damage, or it can let the spindle head sag during a tool change, making alignment impossible. I have debugged drift problems on machines ranging from small gun drills to large BTA systems with 10-ton feed forces. ...
A machine that will not start stops production immediately. I use a systematic approach to find the problem quickly, typically in under 15 minutes. In my experience, roughly 85% of no-start situations are resolved by the first four checks on this list. I designed this flowchart so operators can run through it without calling a technician for every issue. The Four Quick Checks (85% Success Rate) I have trained every operator to run these four checks before picking up a phone. These resolve the vast majority of no-start situations. ...
Machine sounds are a diagnostic tool that requires no instruments and no cost. I listen to the machine at the start of every shift and note any changes from the normal sound. Over years of doing this, I have learned to recognize specific sounds and associate them with specific problems. Catching a problem by sound before it causes a failure saves downtime and repair cost. Sound Types and Their Causes Different machine problems produce different sounds. I have categorized the sounds I hear most often on deep hole drilling machines and their most likely causes. ...
Machine vibration during deep hole drilling causes chatter marks on the bore surface and reduces tool life. I have traced most vibration problems to three root causes: foundation issues, worn bearings or drive components, and workpiece resonance. Each cause produces a different vibration pattern, and identifying the pattern is the first step toward a fix. Vibration Diagnosis by Pattern I have learned to recognize vibration patterns by observing the chatter marks on the bore surface and feeling the machine during operation. The following table summarizes the patterns I have encountered and their most likely causes. ...
I had this one machine, a Mollart 750, that started drilling holes at a slight angle. Not enough to scrap parts right away, but enough that every hole was trending toward the low side of the tolerance band. The operator on the day shift kept adjusting his offsets to compensate, and the night shift guy was doing the same thing in the opposite direction. Nobody talked about it, so the problem festered for about two weeks. ...
What Tool Runout Is and Why It Matters Tool runout is the amount by which the drill deviates from true rotation. Imagine a drill that is spinning on center but the tip is 0.02mm off to one side. That drill cuts a hole that is 0.02mm larger than the drill diameter at a minimum. I check tool runout as part of every setup, not just when problems appear. The check takes 30 seconds and tells me whether the tool is going to produce the correct hole size. It is the fastest quality check I can perform. ...
I have lost count of how many times I have seen a shop chase tool breakage or surface finish problems for weeks, only to discover the real culprit was a coolant pressure issue. The machine gauge reads fine, but the pressure at the tool tells a completely different story. Coolant pressure problems are the most common root cause of deep hole drilling issues I encounter. Here is my systematic approach to diagnosing them. ...