As I understand it, the field coils and armature windings in a DC motor are insulated and this insulation can 'burn off' if the motor overheats, causing a short circuit to develop. What is the material coating the windings and coils in a DC motor? In the examples of the insides of DC motors that I have seen, the windings still retained the look of copper wire – does this mean that the coating is transparent? If so, is this always the case or are there winding coatings that are not transparent?
Electronic – DC Motor Winding Insulation Material
dcinsulationmotor
Related Solutions
If the motor has no permanent magnets and separate rotor and stator windings, then yes you can control it either way. However, such motors are usually intended to be controlled one way or the other. For example, some windings will have significantly higher inductance, which makes controlling them slower or requires higher voltage.
I think you may have found a good example of something that I've been looking for which came up in my answer to this question. Namely, the difference between a sinusoidally wound motor and a trapezoidally wound motor.
The way in which a motor is wound controls the distribution of the magnetic flux density throughout the motor. Which in turn controls the shape of the Back-EMF, which in turn dictates how best to drive the motor (i.e. which commutation method you choose). The different control methods can be read about in the aforementioned answer.
The below diagrams are taken from the master's thesis of James Mevey. This first diagram shows two simplified motors. Each has only a single winding. The motor on the left has "sinusoidally shaped" magnets and the motor on the right has "trapezoidally shaped" magnets.
The resultant flux densities look like so:
Having magnets of the shape in the right hand motor and modifying the distribution of the windings would have a very similar effect.
I think that your "45° orientation" motor is sinusoidally wound. And if you were able to look at how the windings are connected and overlapped you should be able to see how the magnetic field would get stronger and weaker in a sinusoidal pattern.
And I think that your "0° orientation" motor is trapezoidally wound. Which you can almost see since the windings are distributed in just a few big blocks.
As for your "90° orientation" motor, I think you mean this:
Which is a whole different beast. That is a picture of Shane Colton's Less Epic Axial Flux (LEAF) motor.
The motors shown at the top of my answer and in the OP are radial flux motors. In this design, the rotor is on the inside (or occasionally on the outside) of the stator windings. In an axial flux motor, the rotor is in front of the stator windings.
The benefits of an axial flux motor are that it can be made thinner and lighter allowing it to fit better into certain geometries and change direction quicker.
Visualization of the rotating magnetic field can be difficult without good software.
But usually a good motor manufacturer will provide you with all the details on how best to drive their motor on the side of the box. Still, the references in the answer I linked above and in this answer provide a wealth of information (perhaps too much) on what exactly is going on inside a motor as it's driven.
Best Answer
Wire used for motor windings, transformers and other electro-magnetic applications is called magnet wire. Magnet wire insulation is similar to polyurethane varnish. However is is developed specifically for electrical insulation use. As you have observed, the insulation is quite thin yet able to withstand the normal operating temperature and voltage required for motor windings. It is not completely transparent. It is sometimes colored green or other colors that do not look like copper. The most common color is similar to copper. There doesn't seem to be any particular reason to use other colors.