The overall aim of winding in terms of electric motor production is to place turns or coils of wire around the metallic core of the motor. Once this is done, the winding will then generate the magnetic flux that pushes and pulls the magnets and the rotor, creating torque.
While malleable copper may be the most preferred metal for the purposes of winding, aluminium is widely used in various applications. Can the quality and performance of aluminium windings compare to those comprised of copper? This is a question that has been discussed and debated over many years. During the 1960s and 1970s, many motors were wound with aluminum, however its use would reduce considerably from the 1980s. Using aluminium requires more turns and/or a larger diameter wire. This can mean the size of the motor can increase, which may not be ideal or even feasible in some instances.
What are the advantages and disadvantages of each metal in terms of their use for motor windings?
Copper is physically heavier and a significantly more expensive option than aluminium, however it is a lot stronger and can carry almost twice the current capacity of aluminium. As a finite resource, you might say there are limited amounts of copper on the planet (within all known sources of extraction), however there is little threat of it becoming depleted any time soon. With its great reusability, it can be recycled and live on in different forms for longer.
Copper requires less area of conduction for the same current rating. Copper wires are easily connected to each other and other metal conductors. There is also no risk of galvanic corrosion with copper wire, and repairs can be done more easily. For many applications where volume or easily making reliable connections is paramount, the use of copper will be preferable.
Copper windings may not be suitable for the following reasons:
Aluminium is a cheaper, lighter alternative and is readily available. It is also one of the most highly conductive metal elements. Aluminium windings can be used for applications where high efficiency and volume are not high priorities, for example, a motor that is only required to work intermittently for very short periods of time.
Any application that places priority on cost or weight could be a contender for aluminium windings. Aluminium windings are used in overhead power lines and transformers, as the metal is around half the weight of copper, meaning lower costs for supporting structures. Aluminum also costs less than copper, and even though an aluminium conductor will need to have a larger diameter and more windings, copper will still be more costly than the additional material required.
Aluminium windings can be unsuitable for the following reasons:
As this has long been a hot topic in many engineering industries, we can only add in our opinions and discuss the advantages and disadvantages of each option. When looking at reliability and life span, along with overall quality, there is no doubt that the use of aluminium windings can be just as good as the use of copper. That being said, efficiency and cost will play big parts in the comparison, so this should be factored into the decision-making process.
Read more on different winding methods and techniques here>>