Why Machine Warm-Up Matters for Deep Hole Drilling Accuracy
The Thermal Reality of Machine Tools Every machine tool changes shape as it warms up. Steel expands by roughly 0.012mm per meter for every 1 degree C temperature increase. A 2-meter bed that heats up by 5 degrees C grows by 0.12mm. That is enough to push a hole out of tolerance. I have measured this on my own machines. A cold machine at 18 degrees C in the morning produces different hole positions than the same machine at 28 degrees C after running for two hours. The difference is not hypothetical — it shows up on every first-part inspection. ...