What is the optimal spindle for CNC?

2024 Author: Howard Calhoun | [email protected]. Last modified: 2023-12-17 10:16

The CNC spindle is the most critical part and the most loaded unit. For the correct choice, it is always taken into account that the motor power and the mechanical strength of the kinematics must exceed 2 times the calculated values. This is required to protect expensive parts when wedging.

Basic information

Programs for CNC machines are written according to the rigidity of the structure and the maximum speed of the spindle. When milling, the probability of breakage of a rotating tool from heat or metal fatigue should be taken into account. Therefore, safety clutches are often installed, designed for specific dimensions of the motor shaft and chuck diameter.

All programs for CNC machines are first worked out step by step without moving the axes. When the user is 100% sure that the spindle cams will not be affected, then they start working with movements in stepping mode or single cycles. When the check without a workpiece is over, they proceed to the direct cutting of the part.

The CNC spindle is an expensive unit and the most powerful, sohowever, it can be easily damaged by careless handling of equipment. Some systems have complex corrector calculations, the incorrect definition of which results in lengthy repairs. To work on each new machine, the operator must be retrained beforehand, even if he already has experience on a similar stand.

Parameters

CNC spindle should be selected according to the following criteria:

• Type of unit cooling: air, liquid.
• Spindle motor power and gear ratio.
• Engine type.
• Type of bearings and how to lubricate them.
• Operating modes, type of braking system.
• Positioning accuracy and type of tracking sensor.
• Spindle mounting

In addition to the above parameters, the design of the motor itself is also important: the number of windings, the type of rotor, the way the load is removed and applied to the windings. The torque and the possibility of adjustments for the centers of the node relative to the feed axes are taken into account. Chucks should also change: self-tightening, hydraulic, manual, pneumatic.

The CNC spindle is chosen taking into account the possibility of changing consumable parts. You should look at the options for available bearings that are available in stock, find out about delivery times. It may turn out that because of a small consumable, production will stop for a long period, or you will need to pay ten times the price for manufacturing a part. A small spindle for a CNC milling machine should have a lightweightdesign and small dimensions.

What can you make your own knot from?

The spindle for a CNC router for wood, plastic and other soft materials can be a conventional electric drill. It is important to set it according to the level and measure the beats of the cutter. This is a cheap option that allows you to improve an existing design.

Any motor with a finely aligned tool will work as a rotating axis. A reliable and rigid spindle mount is selected. Axial play should not be more than 0.01 microns for most holes. A drill is suitable, a resourceful drill, you can even adapt the engine from a washing machine or sewing machine. Which spindle is suitable in a particular case depends on the goal. The type of material, the required dimensional accuracy of the part, the workload in the automatic cycle are taken into account. You can also order ready-made solutions in the online store.

Custom Engines

Computer Numerical Control (CNC) is used to improve the accuracy of manufactured parts and reduce production time. For a single product, the cost of equipment exceeds the amount invested in its release. It will be cheaper to order the part from any metalworking company.

For a homemade spindle, ready-made motors are ordered. Popular DC motors, synchronous and asynchronous. Turnovers of 12 thousand for such motors are not the limit. Additionallya manual or automatic transmission can be used. Powerful spindle motors require a stable power supply. This is their shortcoming. But if you put a simple drive and a motor with feedback, then on such a machine it is already possible to process more complex products. An additional axis is introduced into the CNC, which can hold not only the cutter, but also cylindrical parts.

Which is better for custom engines?

Factory motors have already been balanced shaft and selected bearings with minimal runout. It remains only to put the finished engine on a standard mount and set the alignment on the indicator stand. Milling precision is required in the production of printed circuit boards, kinematics parts.

Synchronous motors have shown themselves well in the manufacture of jewelry parts by engraving. Permanent motors have a low noise level during operation, which can be useful for managers trying to improve their production. However, they have a property to warm up during operation at high speeds. Therefore, it will be necessary to supply separately and cooling, at least air.

Pros' Choice

More expensive spindle motors are necessarily equipped with liquid cooling. They have higher positioning accuracy, sufficiently powerful torque, and reliability several times higher than indicated. Usually they are mounted on 3-4 bearings, and not on 2, like classic motors. This results in minimal tool or workpiece runout in the chuck.