Why do milling spindles fail more often than turning center spindles?
Rajesh Mandlik
MD at Setco Spindles India Pvt Ltd, Director Strategic Business Development (Setco Asia)
Why do milling spindles fail more often than turning center spindles?
If you observed that population of CNC lathe is definitely more than VMC and HMC put together. Still we have observed that we recondition less of turning center spindles than machining center spindles. We tried to find out reasons.
- Turning center spindles are normally stationary. While machining center spindles move. That being the case, lot of engineering optimisation has to be done while designing milling spindles like weight reduction, using lighter bearings. This leads to the fact that you get vulnerable spindle for accidents. As against this turning center spindles are always rugged and equipped with double row cylindrical roller bearings with double row angular contact thrust bearings.
- In turning center spindles chuck is fitted on respective taper and it is not removed unless there is change in setting. As against this, in milling spindles tool is changed thousand time in a month. Even if slightest misalignment in setting ATC, there is every chance of damaging spindle tapers.
- Turning center spindles are used up to 6000 rpm max. Comparatively milling RPM has gone up to 30000 rpm.
- Normally machining is co axial in turning center as against in Milling long boring bars, reamers create abnormal cutting forces, thus leading to deterioration of bearings.
There are many more reasons. No wonder that even if you have 60 Turning centers and 10 Milling machines, you end up paying more time and money on reconditioning of milling spindles than turning center spindles.
Rajesh Mandlik (9822454204, RajeshM@Setco.com)
Quaker chemicals sales , Mechanical ,Industrial Engineering Professional
8yPractical Very good analysis
Vice President - Sales & Marketing at Felsomat India Pvt.Ltd.
8yDear Mr. Rajesh, A good article and analysis of the causes of failures in spindles; Additionally, I feel there are two other important causes for the higher failure of the Machining center spindles; 1. In case of a Turning center the heat at the cutting point gets transferred through out the component and due to better cooling of the component the heat transferred to the spindle is less, hence these spindles get less heated; in the case of a machining center spindle the tool gets heated the maximum and this is in turn transferred to the spindle through the tool holder, thus machining center spindles get more heated up and consequently faster failure of the lubrication system / bearing / spindle, 2. In case of turning centers the cutting force is distributed between the fixed single point tool and the rotating component / spindle, so load on the spindles is lower, whereas in the case of a machining center spindle most of the intermittent cutting load is transferred to the rotating multipoint cutter and from there to the spindle. So these spindle have to endure higher cutting force; The combination of higher cutting force and the higher raise in the temperature in Machining center spindles leads to higher failures. Best Wishes
Superannuated from Tata Motors
8yVery logical explanation. You are doing very goodwork. Keep it up.
CEO at AIIC, Founder at Sushrut Designs Pvt. Ltd. incubated @ BHAU, COEP, Parenting Coach,
8yThis should serve as design inputs for people designing machines. Maybe you should bring this to their notice..!
Assistant Project Superintendent (Nuclear)
8yBoth analysis are great however if you don't perform regular maintenance on CNC machining centers you will continue to have mechanical/electrical failures...maintenance is a must.