Thread: How do I Roll Aluminium round bar?

I have 8 meters of aluminium round bar, diameter 12mm (1/2"). I need to roll it into 33 rings, each having an outside diameter of 125mm (about 5"). Every company I've asked say that it's impossible to do it with rollers because the rings are too small. I've heard that there's a way of doing it without using incredible machines. Does anyone know how I do this? Bearing in mind I have next to nothing in regards to machinery. Could anyone give me a basic step-by-step way of doing this please? Thank-you very much. Ben

Get a short length of 4 1/2 inch OD pipe and wrap the aluminium around it. Keep going till you have the whole lot wrapped onto it. Make sure you keep the aluminium right up next to the previous ring. Then cut down one side of the wraps, presto, heaps of 5" rings. They will be a little bit offset but you wil pull that straight pretty easily.

Dan

Originally Posted by DanP

Get a short length of 4 1/2 inch OD pipe and wrap the aluminium around it. Keep going till you have the whole lot wrapped onto it. Make sure you keep the aluminium right up next to the previous ring. Then cut down one side of the wraps, presto, heaps of 5" rings. They will be a little bit offset but you wil pull that straight pretty easily.

Dan

I second what DanP said. The ease with which you can wrap the aluminium bar around the pipe will depend on which alloy you have. My guess is that if you have a 1000 or 3000 series alloy then you should be OK. A 5000 series for example might be a bit of a problem. Once you wrap the bar around the pipe you can probably expect a bit of spring back. To counter this you might need to go with a length of pipe with an OD smaller than the 4 1/2 OD Dan has suggested.

Regards,
Mirboo.

If the rings are to be rejoined then you will pull them in to the right diameter. If not, use a 4" pipe. Problem is, you'll end up with a big gap.

Another option is to mak a small set of rollers yourself. Using 2" ID seamless pipe, so that you can press some bearings in to the ends. Don't forget to stick a bolt through the bearing before you press them in. Set up similar to this - o°o Put a crank on the front bottom roller so that you can turn it by hand.

Make the bottom rollers about 1/2" gap between them and make the top roller adjustable for height. That way you can roll about any size you want, including tapers.

Dan

PS. I haven't done this myself but I can't see any reason why it wouldn't work. I plan on making one for when I build a cyclone.

Clamp one end to the hills hoist post and go for a walk around it.

Not quite sure how you can do it per se, but you are going to need more ally. About 14m worth to get 33 rings.

If it were me, I'd give the rollers Dan mentioned a try. Wrapping 12mm ally bar around a pipe is not going to be fun, and I think you have a very good chance of getting a gemometric shape, not a circle/ring. Using rollers would help make sure they are round, not little bends joined by flats.

(Actually, if it were reeeally me, I'd cast them and be done with it.)

Thanks very much everyone! I've just been speaking to a friend who works in Airbus and he recons he could anneal th round bar for us in work to soften it in order to be able to bend it. First i must find out which alloy i've ordered and what the quality is.
Owen

There are machines made for rolling round bar, but finding someone with one of those is probably not the problem, you are trying to work with an extrusion , the more bendable alloys, 3000 series are not extrudable, hence you end up having to buy 6000 series in a t650 or other tempered state that is next to impossible to form without annealing first or heating to temp at forming without having stretch and cracks, I suggest you cancel the order for the round bar, order aluminum tubing id/ od to cover your needs, and have the rings machined.

8ball

Originally Posted by 8ball

There are machines made for rolling round bar, but finding someone with one of those is probably not the problem, you are trying to work with an extrusion , the more bendable alloys, 3000 series are not extrudable, hence you end up having to buy 6000 series in a t650 or other tempered state that is next to impossible to form without annealing first or heating to temp at forming without having stretch and cracks, I suggest you cancel the order for the round bar, order aluminum tubing id/ od to cover your needs, and have the rings machined.

8ball

I'd agree with 8ball but then I suppose that would be OK if Owen wants square faces. Otherwise it won't be so easy putting on radii on both faces.

you can radius all four corners on a lathe to get a perfectly round ring, just takes several setups changing from internal to external chucking, and visa versa

Hold the phone.

You have a friend who works for Airbus that can anneal it?

Why not ask him to bend the stuff while he's there? Surely they have bending machines suited to ally there, unless they are all CNC stuff...

Either way, ask him how to do it, if he has access to an oven, he either knows hw to do it easily, or can find out easy enough.

Originally Posted by 8ball

you can radius all four corners on a lathe to get a perfectly round ring, just takes several setups changing from internal to external chucking, and visa versa

Hi 8ball,

Have you any experience on a lathe?. The reason I ask is that as you say it can be done but to 33 rings:eek:. If you had to pay for the labour (time) it would cost a small fortune .

Cheers
David

No I have no experience on a metal lathe, but I am a purchasing agent and outsourse machining as a job. I was referring to a CNC lathe.

Depending on the alloy, some aluminium will only have a limited window at the annealed state in which to work. I don't mean working while its hot, but after its cooled it will continue to harden in air & after only a couple of hours will be in a hardened state again. Don't necessarily think it can be annealed somewhere, taken home and worked with at your leisure!!:eek: And further working may also harden it!
Good luck.

Originally Posted by Andy Mac

Depending on the alloy, some aluminium will only have a limited window at the annealed state in which to work. I don't mean working while its hot, but after its cooled it will continue to harden in air & after only a couple of hours will be in a hardened state again. Don't necessarily think it can be annealed somewhere, taken home and worked with at your leisure!!:eek: And further working may also harden it!
Good luck.

Background

The application of the term heat treatable to aluminium alloys, both wrought and cast, is restricted to the specific operations employed to increase strength and hardness by precipitation hardening thus the term heat treatable serves to distinguish the heat treatable alloys from those alloys in which no significant strength improvement can be achieved by heating and cooling.

The non-heat treatable alloys depend primarily on cold work to increase strength.

Annealing

Annealing is applied to both grades to promote softening. Complete and partial annealing heat treatments are the only ones used for the non-heat treatable alloys. The exception is the 5000 series alloys which are sometimes given low temperature stabilisation treatment and this is carried out by the producer.

Annealing is carried out in the range 300-410°C depending on the alloy. Heating times at temperature vary from 0.5 to 3 hours, conditional on the size of the load and the alloy type. Generally, the time need not be longer than that required to stabilise the load at temperature. Rate of cooling after annealing is not critical. Where parts have been solution heat-treated a maximum cooling rate of 20°C per hour must be maintained until the temperature is reduced to 290°C. Below this temperature, the rate of cooling is not important.

Solution Heat Treatment

This is applicable to the heat treatable alloys and involves a heat treatment process whereby the alloying constituents are taken into solution and retained by rapid quenching. Subsequent heat treatment at tower temperatures i.e. ageing or natural ageing at room temperature allows for a controlled precipitation of the constituents thereby achieving increased hardness and strength.

Time at temperature for solution treatment depends on the type of alloy and the furnace load. Sufficient time must be allowed to take the alloys into solution if optimum properties are to be obtained.

The solution treatment temperature is critical to the success of the procedure. It is desirable that the solution heat treatment is carried out as close as possible to the liquidus temperature in order to obtain maximum solution of the constituents. Accurate furnace temperature and special temperature variation must be controlled to within a range of ±5°C for most alloys. Overheating must be avoided i.e. exceeding initial eutectic melting temperatures. Often the early stages of overheating are not apparent but will result in a deterioration of mechanical properties. Proper solution heat treatment of the aluminium alloys requires an expert knowledge of the alloy being treated plus the correct heat treatment plant.

Quenching

This is a critical operation and must be carried out to precise limits if optimum results are to be obtained. The objective of the quench is to ensure that the dissolved constituents remain in solution down to room temperature.

The speed of quenching is important and the result can be affected by excessive delay in transferring the work to the quench. The latitude for the delay is dependant on section and varies from 5 to 15 seconds for items of thickness varying from 0.4mm to 12.7mm. Generally, very rapid precipitation of constituents commences at around 450°C for most alloys and the work must not be allowed to fall below this temperature prior to quenching.

Another factor to be considered in quenching is the work load and the ability of the quenchant to extract the heat at sufficient rate to achieve the desired results.

The usual quenching medium is water at room temperature. In some circumstances slow quenching is desirable as this improves the resistance to stress corrosion cracking of certain copper-free Al-Zn-Mg alloys.

Parts of complex shapes such as forgings, castings, impact extrusions and components produced from sheet metal may be quenched at slower quenching rates to improve distortion characteristics. Thus a compromise must be considered to achieve a balance of properties in some instances. Quenchants used in slower quenching applications include water heated to 65-80°C, boiling water, aqueous solutions of polyalkalene glycol or forced air blast.

Age Hardening

After solution treatment and quenching, hardening is achieved either at room temperature (natural ageing) or with a precipitation heat treatment (artificial ageing). In some alloys sufficient precipitation occurs in a few days at room temperature to yield stable products with properties that are adequate for many applications. These alloys sometimes are precipitation heat treated to provide increased strength and hardness in wrought and cast alloys. Other alloys with slow precipitation reactions at room temperature are always precipitation heat treated before being used.

In some alloys, notably those of the 2xxx series, cold working of freshly quenched materials greatly increases its response to later precipitation treatment. Mills take advantage of this phenomenon by applying a controlled amount of rolling (sheet and plate) or stretching (extrusion, bar and plate) to produce higher mechanical properties. However, if the higher properties are used in design, reheat treatment must be avoided. Where natural ageing is carried out the time may vary from around 5 days for the 2xxx series alloys to around 30 days for other alloys. The 6xxx and 7xxx series alloys are considerably less stable at room temperature and continue to exhibit changes in mechanical properties for many years. With some alloys, natural ageing may be suppressed or delayed for several days by refrigeration at -18°C or lower. It is common practice to complete forming, straightening and coining before ageing changes material properties appreciably. Conventional practice allows for refrigeration of alloys 2014 - T4 rivets to maintain good driving characteristics.

The artificial ageing or precipitation heat treatments are low temperature long time processes. Temperatures range from 115-200°C and times from 5-48 hours. As with solution treatment accurate temperature control and spatial variation temperatures are critical to the process and generally temperatures should be held to a range of ±7°C.

The change of time-temperature parameters for precipitation treatment should receive careful consideration. Larger particles or precipitates result from longer times and higher temperatures. The objective is to select the cycle that produces the optimum precipitate size and distribution pattern. Unfortunately, the cycle required to maximise one property, such as tensile strength, is usually different from that required to maximise others such as yield strength and corrosion resistance. Consequently, the cycles used represent compromises that provide the best combination of properties.