Spindle selection

The main types of spindle available are:

Cartridge type spindles


These require a separate motor for drive, as a result the whole assembly becomes very bulky and cumbersome however does enable the motor to be changed for varying applications or multiple motors to be added to increase torque at given RPM values.

All in one spindles



These spindles are all in one units that require power inputs, positional inputs (If acceptable) and water feeds if water cooled. This will be the type of milling spindle I will be selecting due to its compact nature and the aims and objectives of the machine. The machine will be run within a very narrow RPM range as a result a lower speed and higher torque motor for milling other materials will not be required.

The criteria set for the spindle selection are:

Must have a minimum power output of 1kw @ 19500 rpm
Must be water cooled to allow long duty cycles
Ideally should have function to facilitate automatic tool changes.

This spindle sold by JiaLing FeiLong Automation Equipments Co. LTD satisfies all the requirements other than the speed requirement. This is a maximum of 1800rpm. However I can slow the feed of the machine to compensate and increase the depth of cut to maintain material removal rate.

http://www.aliexpress.com/item/EN030-Motor-Spindle-for-CNC-milling-with-ATC/620661845.html


The cost is £2233 delivered from China.


Run out is stated at less than 3 micron

The main issue with this item is the cost.

A 2.2kw all in one spindle motor can be bought for £205

This also contains part of the electronics system to run the spindle.

http://www.ebay.co.uk/itm/200687842858

As this machine is not a production machine with the increase in price to utilize an automatic tool changer it just does not make it a viable option and a manual tool changer type spindle will have to be used.