Recommendations
The electrospindle manufacturer recommends using high-precision ER collets, which significantly impacts the quality of the work performed and extends the lifespan of the bearing system. The table below shows two manufacturing precision classes for ER collets.
It is well-known that improperly seated tools result in incorrect dimensions in milling operations, and unwanted vibrations weaken the spindle’s bearing system. This phenomenon is exacerbated with massive and long tools. Therefore, every effort must be made to ensure tools are mounted axially. Crucial here is not only the collet and the cutter itself, but also the ER nut that clamps the collet in the internal taper of the spindle shaft. The groove on the collet’s external front face must align precisely with the eccentric ring (or retaining ring) within the clamping nut and rotate within it without resistance.
An improperly mounted tool collet will not ensure concentricity and will, in fact, prevent normal operation. If overtightened, both the collet and the nut can be damaged.
According to the manufacturer’s recommendations, in addition to using good quality tool collets and correct mounting techniques, it is crucial to maintain the cleanliness of all these component surfaces. It is recommended to clean them with a mixture of gasoline and oil or to use commercially available, ready-to-use low-viscosity (thin) cleaning-lubricating agents.