High speed machining equipment is likely the biggest capital investment a shop makes, and its proper care and maintenance is critical to reducing costly downtime, repair bills, and replacement while maintaining throughput and efficiency. Spindles are the lifeblood of CNC milling and CNC turning machines, and no one wants to see production negatively impacted due to poor maintenance practices. Upkeep is a critical component in keeping costs down while running an efficient and money making CNC machine center. Here are a few of our favorite tips to cut down on the number of repairs:
A critical care function you can perform. Maintain lubricants at the OEM recommended levels, keep clean (check for discoloration), and replace according to the suggested maintenance schedule. Daily inspection of oil levels in all operating tanks including; gear boxes, spindle chillers, hydraulic units and central tanks must be adhered to, in addition to ensuring that all spindle bearings are properly lubricated.
Before powering on any CNC machine, make sure that coolant levels are correct and that strainers are clear of any debris. If so equipped, chiller systems are designed to warn you of a spindle problem; therefore it is critical to ensure that they are running properly. In addition, be certain that your coolant is aimed correctly and not splashing directly on top of the spindle. This can result in damage.
If you notice increased vibration or unusual noise, the spindle bearings have become worn out and need replacing (use OEM technicians and/or parts). Keep an eye out, and an ear out, for any triggered alarms on your milling and machining equipment.
The pull force of the spindle spring is critical to proper CNC machining; it secures the tool holder in the spindle. If this force becomes too weak, excess vibration, runout, and damage to the spindle and machined parts could result. Check the spring force regularly using a "draw bar pull force test". It is also good practice to perform routine runout tests using an OEM recommended spindle test bar.
When running any CNC milling machine, avoid any accumulation of chips near the end of the spindle. These have a tendency to work their way inside the bearings, limiting their lifetime, resulting in potential damage to the spindle.
To sum up, if you're not producing accurate and quality machined parts, if you notice a rise in operating temperatures, vibration levels or unusual noise, then you have spindle problems. With proper care and regular maintenance, including investment in quality spindles to begin with, you can significantly reduce costly downtime, errors, and repairs. Take care of your most significant investment, and it will take care of your CNC machining operations.