aluminium wire for motors

there will be higher inefficiency due to the higher resistance which would also cause higher heat that would have to be dispersed.

phoenix911

They tried using aluminum for house wiring a few decades back, but there were so many problems, including more than a few fires, that I believe it is banned here in the USA, or maybe only California. Aluminum IS used for outdoor feed lines, where only trained professionals connect it.

Getting through the oxide layer that is always on the aluminum, and keeping it off, is the biggest problem. You can't solder to aluminum, so crimping is the only connection method I know of.

If there is any flexing, aluminum work-hardens much faster than copper, so will break sooner.

If I knew a motor had aluminum wire (other than the cast-in aluminum of the squirrel cage rotor), I would never buy it.

Keep the copper! In the long run, quality is more important than price.

Exactly, especially considering the application.

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Don't worry about the Ants when the Elephants are kicking the crap out of you!

Forming Aluminum conductors, especially at tight bend radius with respect to conductor cross section, will result in surface crazing and reduction in conductor cross section due to the ductibility of Aluminum. The surface oxidize, Aluminum Oxide, acts as lubricant and lowers the thermal conductivity. This is why it is required to use a "Anti-Slip Agent" in service entries in the US. The reduction in cross section can be a serious problem for "Spot Heating" that can lead to exponential reduction in cross section. This is why in transmission lines the Aluminum wires have a steel or Arimid core and often a combination of both.

To sum it up, you maybe playing with a potential disaster when you include centrifugal forces if rotor is wound.

Also you will need bigger size of stampings to accommodate bigger cross section of aluminium wires, so motor frame size will change.

Suresh Sharma.

Not much I can add to everything already said... Only that if few people are telling you, you are drunk, you better go (not drive) home and go to sleep...

How could I disagree with that...yeah, just sleep on it.

I'm amazed how some give their opinion without having any idea what are they talking about, aluminum winding is not new at all, its been there for decades I know because i've been working for major motor companies such as Danaher motion, General electric and Regal Beloit for almost twenty years, you can use an "Ampomator" its an AMP crimping machine, (yes crimping is the only correct guess you had out of the whole thread). And don't go home to sleep just because a few guys say you're drunk, remember that you havn't had a beer.

Good luck

why don't you give him more help on the subject then?

I am not debating the cramping issue here but, if his ALU wire isn't even insulated for the purpose so, how would he know what to do?

The ALU wire is definitely been used in earlier times even is stator coil applications in heavy-duty stater motors, if there was no copper wired coil available. The only reason it was possible to use because there was enough room for the bulkier ALU coil also however, it was always obvious that ALU was a poor choice against Cu.

In smaller applications it is almost incomprehensible to understand the reason behind it at all. The enamel insulation on ALU is not even a common practice and he would need to do it before he could do anything.

If you willing to explain why to use ALU wire instead of copper in a small motor then I'm all ears coz I'm curious.

other than you........who said aluminum is new?

And thanks for your conformation input on crimping

I have seen smaller H.P motors being mfd. by a small mfr. They worked well but comments made by most of us are valid and technically correct. Do you feel that our comments are incorrect?.No need for going to sleep or drinking beer.

Suresh Sharma.

If you are saying that you have uninsulated wire that you are going to varnish to insulate it, you are not drunk but are insane. Get professional help. Take that any way you want. You have received lots of professional help here. Don't let one "professional" talk you out of it.

You still don't get it son, let me explain just a little, (do your own research):

After winding, coil insertion, connecting, lacing and forming, you need to varnish the stator to give it machanical strenght, heat dissipation but most important, dielectrical streght, you can also use a resin trickle process, and there are several compounds for this porpuse. Forget about using uninsulated aluminum wire, we the Pros, know Phelps dodge, Essex and others already sell you coated aluminium wire.

Regards

Nitin wrote: i wish to use aluminium winding wire for small motors of size of 0.1-0.5 kw for fans of 220V.

Other than weight saving what possible reason would you have for attempting to use aluminum? Cost saving? Hardly likely.

Given the technical engineering reasons against using aluminum in small motors it seems inconceivable that aluminum would be a benefit and have advantages over copper.

It would be helpful if you could provide better insight into the reasons for trying to use aluminum. Several people have mentioned these reasons. Aluminum has more resistance thus need greater diameter wire to carry the same current. Current is what determines the strenght of the magnetic field. Heat creation is going to be higher so you need more air space to allow cooling air flow. these are fractional horse power so there isnt much room for clever engineering or high tech solutions.

You will have more problems in making secure wire connection to the external world. There will be more metal incompatibility problems. Your manufacturing equipment will end up being custom made since the normal copper wire oriented tooling is not going to be compatible in all aspects. As mentioned you will have to take greater procautions against work hardening and stress cracking of the aluminum wire.

Given the stated size of motors these wires would be very fine and thus more prone to breakage. Yes several companies do provide varnish coated aliminum wire but will they have the size you need? For lack of volume market they are not likely to have it as a stock item.

So back to the original question. Why would you even consider doing this? Do you not think many others have also thought of this and explored the possibility?

Well, it is a "possibility" widely explored by others, since they're actually selling not only induction motors but servo and steppers too. The only thing nitin has to do is call a sales representative from AMP to get advise on the crimping equipment; and Essex for a broad range of aluminum wire specs, where he can see the temp rise of each and the wire gauge for his products, along with the recommended varnish.

Wether you like it or not, aluminum wound motors are on the market for a while.

Hi guest

please register & join

I'm sure you have a lot to share!

There are a lot of reasons aluminum would be a pain, connections being at the top of the list.

Using conductive paste in the crimped connectors & a nice terminal block like SEW/Eurodrive uses would be nice. depending on the cost & service life of the finished product/application.

I guessing the main reason Nitin is exploring this is the high cost of copper!

The original stipulation was for: small motors of size of 0.1-0.5 kw for fans of 220V.

This is also called frational horsepower motors. Typically these use wire sizes that are very fine, sometimes almost as thin as hair. A 500 watt motor being the biggest would still only use something around 20 Ga wire. Since this is not something commonly used in production now, Tooling required to make reliable crimp connections ( or spot welding) would have to be specially made. The cost of such tooling is high enough to drastically offset any saving made by going with aluminum instead of copper. Reliability is the second issue. If the aluminum proves to be prone to breakage within the warranty period, this will also offset the savings made by going to aluminum. Portable fans tend to get knocked about by consumers.

For a given horsepower ( or fraction therof) aluminum wire will have to be larger than copper wires producing same power, so the motor frame will now have to be slightly larger. Frame sizes will now have to be slightly larger, but not necessarily the next size up. This would then be a custom item requiring special dies etc. to make.

Going with the next size up in standard motor frames would mean use of more iron. Again it means a slight but measurable increase in cost. This will also offset any savings derived from going with aluminum.

Something else. The tensile strenght of aluminum compared to copper is also different so coil winder machines will have to be recalibrated. And the workers will have to be trained to work with the more delicate aluminum wire.

I am not saying it can't be done just pointing out some of the pitfalls that can escalate costs beyond a point of being a saving.

I am assuming the OP is doing the cost comparisons now, hence the questions of different materials. In order to get acurate cost figures ; all variables wil have to be accounted for. Otherwise the switch to aluminum wire may prove to be a very costly experiement.

El you are most certainly right,

The ROI [return on investment] is going to be many thousands of units.

Mr. guest can probably enlighten us a bit as to the size of motors that presently use aluminum.

All that being said, I probably wouldn't buy an aluminum wound motor...

Maybe a solinoid, maybe a transformer, coil..

Me neither. At one time I worked as an underground cable splicer. I also spent time finding underground faults in buried utility power cables. 90% of the time the problem was due to aluminum conductors reacting with moisture. More recently I ripped out aluminum wired power cables in a residential situation. There was a mixture of copper and aluminum wires. Some of it dated back to when aluminum was allowed in residential installations.

For overhead power cables in a distribution system I can see the point, but not for finer gage stuff. And the galvanic reaction problems with mating aluminum to copper extension cords. Oh boy!! No thanks!

The main reason for using al. wire is the cost.

WE are making motors for fans which is highly price sensitive and to reduce cost we are considering using enamalled al. wire. I have seen other people connecting wire using a soldering paste (which i think reduces oxidation when the contact is cleaned). After that they solder the wire and then work like a normal motors and make the end connection with the copper lead. Is this technice safe.

PLs let me have your opinion on the same

The main reason for using al. wire is the cost.

WE are making motors for fans which is highly price sensitive and to reduce cost we are considering using enamalled al. wire. I have seen other people connecting wire using a soldering paste (which i think reduces oxidation when the contact is cleaned). After that they solder the wire and then work like a normal motors and make the end connection with the copper lead. Is this technice safe.

PLs let me have your opinion on the same

If you can obtain enamel coated Al wire cheaper than Cu wire than you may consider its use. Alu wire can be soldered at higher temp than solder. However, you can forget about that coz the commutator's still copper and you most likely can only join alu wire to it by crimping. (Any other method may make it more expensive than what it's worth, remember that too! Otherwise what's the point?)

The only thing is - will you be able to fit the right size alu wire coils in those motors?

I still don't think aluminum is a good idea, but come on - the last fan I saw that had a commutator was built before WWII.

If it is just a normal induction motor than he does not have to worry about the commutator issue.

He just simply has to crimp or twist and seal the joints from air to stop oxide. I do not think the connection is gonna be his main problem but rather the size of the coil. Can he fit it in place of the copper coil.

I saw many room fans (I assume that is what he's talking about) have their stator cu coils cramped in their slots. Now try to fit the right sized ALU wire coil in there, unless his stator core can accommodate it. Usually, only the Universal motor has enough space for that not the induction motor.

Also, if the market is so 'price sensitive', how much could he under cut the price of his current cu coil motor by going through all the hassles to switch to ALU wire coil?

(How easy is to get enamel coated alu wire and where would it be used these days still?)

In some applications, aluminum conductors are a good option. Aluminum has better electrical conductivity than copper on a weight basis. This explains why it is the choice bus bar conductor material in many military mobile high power electrical systems. It's true that there are termination concerns, but those concerns can be addressed. Ultrasonic welding works well for joining aluminum conductors. In fact, aluminum has been a conductor of choice for semiconductors for over 40 years. If you have a legitimate reason for selecting aluminum, you can engineer your way around its difficulties.

In fact, aluminum has been a conductor of choice for semiconductors for over 40 years.

That was only because only recently they where able to develop copper for semiconductors just 10 -12 years ago in a lab. And only took about 1-2 years to bring it to market.

phoenix911

You are correct. Copper wire for semiconductors is relatively new. However there are selected applications where copper can not be used. One example is projectile delivered ordnance where the density of copper wire results in deformation of the higher density copper wire under the enormous G forces. Also, it has been determined that material changes must me made to the semiconductor surface metallization in order to make it compatable with copper terminations. This costs money and takes time. Many manufacturers have opted to remain with the simpler and highly reliable aluminum system.

My recommendation is don't do it.

In a past job. We manufactured small (EI-2" thru 5") transformers and inductor chokes. When aluminum was significantly less expensive than copper we chased a cost savings that we never realized. The problems were numerous. We had to purchase welding equipment to attach the aluminum bar terminals to the aluminum sheet windings. Changing from copper to aluminum requires more iron (as posted previously). The aluminum models were larger and weighed more. Because aluminum conducts are larger for the same current carrying capacity, fewer turns could be put onto a core. To compensate, the lamination stack had to increase. The taller lamination stack translated into longer conductors. In the end, the aluminum conductor versions just didn't last as long as the copper counterparts. Unhappy customers as many had to be replaced.

I believe that the problems associated with putting aluminum windings into a motor will befar greater than those we experienced with making transformers and coils. We only had to worry about vibrations fatiguing the conductors from the excitation current. A motor has vibrations originating from the mechanical system as well.

You could try to spot weld the coils.

I have used a special alloy rod to solder/braze aluminum, but doing wire will be tricky. (The temperature band between the melting temp of the rod and aluminum is small.)

Here's a link to one:

http://www.aluminumrepair.com/?src=google&gclid=CLLzsNKz3ZoCFRK1FQodsEsY2w

The savings (for the doubters) Copper is $2.30 +- and Aluminum is $.72 +- Which is over 3 times as much material for the same price.

100,000 units = $158,000.00 in savings.

I do agree, however, it is full of pitfalls.

Today I discovered another potential pitfall to using aluminum wire in frational horsepower electrical motors. I dismantled a RYOBI hand sander that had quit working. It was relatively new but past the warranty period. I love doing these failure analysis since it gives me insight into what does and does not work.

This motor was obbviously designed for fully automated assembly. The stator windings were terminated in Insulation displacement tags press fitted into the plastic coil holder. This is exactly the same technology we used in mass wire terminations back in 1984 production equipment so its hardly new. Guess where thebreak was? Yep right at this tag where the sharp edge had cur into the enamel coating and the copper. My guess is such a termination would never have lasted to end of warranty period. This orbital sander produces enough vibration to fatigue metals and a ID terminal is a prime candidate for early failure.

My advice to the orginal poster is to not only look at cost saving from switching to aluminum wire but consider what it will cost to change your production tooling over to processes and methods that are suitable to aluminum wire. That potential saving of $158,000 cited in the previous post could easily be eliminated in tooling chage overs.

From a previous job as production manager in a coil winding shop I know that all the winders wiill most likely have to be recalibrated to run aliminum wire instead of copper. Total change over is not going to be accomplisned overnight in one shift change. What will the cost be of downtime while you get the new tooling set up?

The change to aluminum wire may be possible but will not be cost effective unless you have adequate volume sales to amortize the additional expenses.

I quickly zeroed in on the fact the coil was open circuit. I decided to inravel the winding to see what had failed. No sign of over load or excess curent. to get access to the actual copper wire ends I pulled the press fit insulation displacemwent terminals.

How thick is the coating on Al wire as opposed to copper nd would he be able to fit it on a fan motor that normally only has just enough room in the core to fit copper coil into?

Above all is Al wire cheaper than Cu once it's coated? This is his main reason contemplating on the idea to switch from Cu to Al.

Coating Al-wire with oxide is much better than ordinary polymeric coating,

but you will not (?) be able to coat without defects.

Defect-free 100V/µm is no problem.

Defects: from scratches or protrusions of the uncoated wire and from too sharp bending.

So necessary: overcoat after winding if best thermal conductivity is wanted or after anodising if not so critical.

RHABE

I saw once Al-wire coated very thin (maybe thinner than Cu-wire) in yellow.

Any idea what kind of coating it might have been?

It looked anodized but because was a thin wire and no magnifier I could not work it out. I never saw Al-wire like that before nor since and I found it on the rubbish tip as a kid scurrying through in search of other things.

Hi,

yellow color may originate from:

a. coloring of porous anodised layer by organic dyes,

b. anodising in oxalic acid,

c. proprietary alloys and processes in anodising,

d. polymeric coating.

So not really a guideline to follow.

RHABE

Hi,

are these al-wire coatings thinner nd have they better electrical strength than the enamel on cu-wire? where can you normally get it from? it's not an every day item as far as I'm aware.

Stephen

Thinner: yes if you have the type of anodising that produces non-brittle coatings.

Better electrical strength: yes, but only if no cracks, so same requirement as above!

Also much better thermal conductivity.

No idea if there is a producer that will sell this, just search.

Experimental coatings I did myself but never tested for elongation or bending radius that is allowed before cracking initiates.

RHABE

Aluminum wire is available with an aromatic polyimide coating known as Kapton. All the Kapton I have seen is yellow colored. It's good stuff, although it has been blamed for some aircraft accidents. I suggest you look at Kapton insulated aluminum wire.

Is it the one they make high temperature resistant insulation tape out of?

We used to use a type of tape at work that was heat resistant and yellow but never knew how to spell it but it did sound like that (Kapton). It wouldn't give in to soldering iron's temp and apparently wasn't cheap.

What about the Flexible PCBs, are they made from the same stuff then?

That's the stuff. It's not cheap but has many excellent dielectric properties, and you normally don't need a thick coating to provide good insulation.