Editor’s Note: This blog post was originally published in and has been updated for accuracy and relevance.
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Aluminum has traditionally been thought of as a difficult-to-measure-material with an infrared pyrometer because it is so reflective and has unique emissivity characteristics. To compensate for these unique emissivity characteristics of aluminum, Williamson developed a multi-wavelength sensor with application-specific algorithms that compensate for emissivity variation to produce an accurate and repeatable temperature measurement. For over 25 years, our multi-wavelength sensors have been helping aluminum extruders achieve accurate temperature measurements during critical steps in the extrusion process. Because our multi-wavelength technology is so unique, we often run into a lot of the same questions from customers as to how it works. Here is a list of our top 7 most Frequently Asked Questions.
Aluminum Extrusion – FAQ
1) Why do I need a multi-wavelength pyrometer?
Aluminum is a non-greybody material, which means that it has low and complex emissivity characteristics. Traditional single and dual-wavelength (ratio) pyrometers are unable to provide accurate and reliable temperature measurements for non-greybody materials.
Single-wavelength pyrometers require an emissivity input. Let’s say your emissivity input is set to 0.05 and the emissivity of the material changes from 0.05 to 0.06. While that is only a small nominal change in emissivity (0.01), it is a 20% change in energy and would cause a big error in temperature reading. Because the emissivity during aluminum extrusion is never constant, a single-wavelength pyrometer is not accurate or repeatable.
For materials with varying emissivity, a dual-wavelength or ratio pyrometer is often used. However, a ratio pyrometer assumes that emissivity variation affects both wavelengths equally (greybody material). Since aluminum is a non-greybody material, it has different emissivity values at different wavelengths and dual/ratio pyrometers cannot accurately compensate for emissivity variation. Enter the multi-wavelength pyrometer with application-specific algorithms designed to characterize infrared energy, emissivity, and measured wavelengths to accurately calculate the temperature and emissivity of complex non-greybody materials.
2) Does the multi-wavelength pyrometer require an emissivity setting? Do I have to change the emissivity depending on alloy?
The short and sweet answer is no. The sensor does not require any emissivity adjustments or tuning of the algorithm to provide accurate measurements. Once you select the proper algorithm for the application, the sensor is ready for operation. When we developed the aluminum extrusion algorithms, we took data from a wide range of press sizes, alloys, shapes, and operating conditions to ensure that we could have one algorithm to cover just about any type of extrusion profile imaginable. Each sensor includes up to 8 algorithms with options for profile measurements at the exit of the press or in the quench zone as well as a variety of different billet measurements.
3) Does the pyrometer need a full field of view?
For the press exit, you do not need a full field of view to make an accurate measurement. The press exit pyrometer can actually tolerate as little as a 10% full field of view and report an accurate temperature. For other applications such as billet temperature, a full field of view is required. Alignment becomes critical for billet pyrometers, and we want to make sure that no mechanical or optical obstructions are in the way.
It is recommended that the sensor is mounted 3-5ft (1-2m) from the billet to make sure it is properly aligned with a full field of view. Special small spot optics are available if greater mounting distances are required.
4) How do we know the pyrometer temperature reading is accurate?
In addition to providing a real-time measure of temperature, the Williamson multi-wavelength pyrometer also provides a real-time measure of emissivity. For a given application we know, more or less, the expected range of emissivity values. For the Press Exit measurement , we can expect an emissivity value of between 0.03 – 0.10 (typically in the 0.05-0.06 range).
When we see the calculated emissivity value in this range, we can be very confident that we are getting an accurate temperature measurement. If we notice that the reported temperature is off and the emissivity value is way outside this expected range, we know that something is not right. We can then check to see that the correct algorithm is selected, the sensor is properly aimed, and the pyrometer is not seeing any reflected energy.
5) How does a Multi -Wavelength Pyrometer reduce error?
The benefit of using a multi -wavelength pyrometer is it will eliminate interference from common industrial obstructions. If you have the appropriate wavelength selected, obstructions such as steam, water, flames, combustible gases, plasma, and laser energy will not cause a reading error.
6) Why does the pyrometer reading disagree with my thermocouple?
Thermocouples and probes are common devices used for taking a contact temperature measurement of a surface. However, there are a couple of issues when taking a contact measurement of a surface. Thermocouple readings can be influenced by a number of different factors which may or may not represent the desired target surface temperature. Common influences on thermocouple temperatures include ambient air temperature, thermal inertia (starting temp of the probe), thermal mass of the probe, surface oxidation, loss of heat through conduction, and also the applied pressure of the thermocouple on the surface.
After some use, thermocouples can also get dull or oxidize and will not be as accurate as they once were, leading to lower reported temperature values. Moreover, some thermocouples will read 40-50°F below the actual temperature right out of the box. Some have even read as much as 100°F too low. The best way to check the accuracy of the thermocouple or probe is to check it against a NIST certified hotplate. Once you determine the accuracy of the thermocouple probe against the hot plate, you can then make a fair comparison between the thermocouple probe and the pyrometer.
7) What are the operating temperature ranges?
The short answer is, it depends. The reason is that every application for a pyrometer is going to vary. We offer 6 different infrared technologies that will allow you to get the most accurate reading. By offering different options we can guarantee that the wavelength options, multiple optical configurations, temperature spans, and accessories will be optimally configured for your application.
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For additional resources about increasing quality and productivity, download our Aluminum Extrusion Best Practices Guide:
The main standard for aluminium extrusion tolerances is European Standard BS EN 755. However, where tighter tolerances are needed, we may be able work to the standards set out in BS EN . There are some circumstances (usually depending on the size and intricacy of the profile being extruded) where we may not be able to improve on the aluminium extrusion general tolerances outlined in BS EN 755. The best way to check the tolerances we can achieve on your project is to ask: we can carry out a review of your proposed profile using dimensioned drawings, and let you know what’s achievable.
How much aluminium extrusion costs per kilo is governed by the London Metal Exchange (LME), taking into account the global market and fluctuations in supply and demand. What this means is that the cost per kilo of aluminium extrusion is never the same. In addition, aluminium is traded in US dollars, which means that we have to take the exchange rate into account.
In order to protect our customers from price fluctuations, we offer prices that are fixed for a month after a quote is first produced. So if the cost per kg of aluminium extrusion increases a day after we’ve quoted you, we’ll absorb that cost.
If you wish to secure a fixed cost per kg for a period of up to 12 months, we can arrange to forward purchase metal as a means of securing this price. Having a fixed aluminium extrusion cost per kg for a year can give you a valuable period of price security that proves particularly helpful in the early days of your business, or in lean times. It also makes good business sense!
Aluminium extrusion weight per metre is calculated from the surface area of the extruded profile. Extruded aluminium profiles come in an infinite range of shapes and sizes, so the aluminium extrusion weight per metre is used to calculate the £/kg cost.
To simplify matters at Edmo, we typically use the aluminium extrusion weight per metre to calculate a cost per piece, so you know exactly what you’ll be paying for each production run. If needed, we can also apply cost units of £/kg and £/metre.
If you have any particular cost requirements, or you’d like to know more about how we calculate our aluminium extrusion weight per metre, please let us know and we’ll be happy to talk you through any questions.
Contact us to discuss your requirements of aluminium extrusions technology. Our experienced sales team can help you identify the options that best suit your needs.
Aluminium extrusion is a metal forming process used to transform lengths of aluminium alloy into objects with a particular cross-section. The aluminium lengths, called billets, are pushed through an extrusion die with a smaller cross sectional area than the billets themselves. The billets take on the shape of the cross section on the die, so they can be used in various applications. The aluminium extrusion process is a relatively quick, simple and cost-effective one, and aluminium is particularly suited to this kind of forming.
We supply a wide range of extruded aluminium profiles to our customers, including products up to nine metres in length. In some cases, we can deliver extruded lengths of up to 12 metres, although this depends on the design of the profile needed. If your project needs any outsize extruded aluminium profiles, please let us know: we’ll either find a way to supply you with what you need, or we’ll recommend a supplier who can.
Yes, our technical team is made up of engineers who are experts in aluminium extrusions. If you have any questions about the right aluminium extrusion alloys for your particular project, one of our team members will be happy to advise. The choice of aluminium extrusion alloys depends on a range of factors, including the product application (how the product will be used), the design, and the surface treatments needed.
Engineering design is part of the complete extrusion solution we offer, and helping our customers identify the perfect aluminium extrusion alloys for the job is just one part of that.
It really does depend on the nature of your project. Wherever possible, we use series aluminium extrusion alloys, as they are widely available and suited to commercial use. Of the available aluminium extrusion grades, we primarily use:
There are other available aluminium extrusion grades, however, there would rarely be a case in which we would need to use these. If you are unsure of whether the available aluminium extrusion grades are suited to your intended application, or would like to know which grade we would recommend, please feel free to contact us.
series aluminium extrusion alloys are widely available and suited to most commercial applications, making them a good choice of alloy for much of the work we undertake for our customers.
This range of aluminium extrusion alloys contain aluminium (of course!), manganese and silicon. These additional elements allow the alloys to undergo heat treatment to improve strength. series aluminium extrusion alloys are also well suited to fabrication such as welding, are versatile and hard-wearing enough for use in a variety of commercial and industrial applications, and offer good corrosion resistance and formability.
Yes, we can access a full range of standard extruded aluminium profiles on behalf of our customers, in addition to a range of pre-treated profiles such as pre-anodised aluminium sheets. But, standard extruded aluminium profiles are just a small part of what we do: we specialise in bespoke, end-to-end solutions, which means that the vast majority of extruded aluminium components and profiles we supply are made according to our customer's exact specifications.
Find out more about our turnkey aluminium extrusion and aluminium fabrication services.
BS EN is the European standard that specifies tolerances on the dimensions and form of extruded precision profiles - in our case, extruded aluminium profiles. In many cases, we can produce to this standard. However, some profile shapes and sizes would prevent us from doing so, which is why our technical team carefully reviews all drawings to verify. We’ll always give you an honest answer as to the tolerances we can achieve on your project, and we never over-promise.
Yes: there are plenty of places online where you can buy a variety of cheap aluminium extrusions and extruded aluminium components, and eBay is just one of them. We’ll wish you the best of luck, and we’ll be here to help you out in the likely event your cheap aluminium extrusions fall short of your expectations.
At Edmo, we’ve got decades of experience in aluminium extrusions, a wealth of technical and engineering expertise, and access to a global network of extrusion suppliers. We’re dedicated to getting the best deals for our customers in terms of price and lead-time, while offering premium quality, complete solutions. Our service can take your aluminium extrusion project from design to delivery, all project managed on your behalf.
Or, yes, you could type in “cheap aluminium extrusions” on eBay…
“Can you deliver aluminium extrusion near me and/or my customers?” is a pretty common query. Edmo’s primary facility is based in Ross-on-Wye in Herefordshire. We’ve always been able to deliver aluminium extrusion to customers across the UK, and it’s quicker, cheaper and easier than ever since we opened our subsidiary branch in Wednesbury in the West Midlands.
While we’re proud of the local communities around our two UK sites, we’re by no means limited to being a regional supplier. Our busy logistics department ensures that we’re able to deliver aluminium extrusion near you and your customers, wherever you and they are in mainland UK.
Aluminium is cost-effective, lightweight and easy to work. However, it’s also very good at conducting heat, which isn’t ideal when it’s used for things like doors and windows. It offers poor insulation in winter and little protection from heat in summer (admittedly not a huge problem here in the UK).
Thermally broken extruded aluminium profiles solve this problem. A thermally broken profile is effectively an aluminium sandwich, and contains non-conductive material that acts as a thermal ‘break’ or barrier. These thermally broken profiles can conduct up to 1,000 times less heat than aluminium alone.
When we say “complex profiles” will usually cost more, what does that mean? Well, “complexity” in terms of extrusions usually hinges on what’s known as the shape factor. An extruded profile’s shape factor is the amount of surface area that’s generated per unit mass of extrusion.
And the reason complex profiles cost more is that the shape factor affects the cost of tooling (creating a die) and the rate of production. Extruding a perfectly circular cross section, for example, needs the least force, whereas a more complex shape needs more.
Of course. We prefer a bit of warning - gives us chance to put the kettle on - but otherwise we operate a completely open-door policy. Seeing what we do first-hand is what convinces a lot of our customers we’re the right extrusion and fabrication experts for them - so why wouldn’t we want to show off our skills?
Make an appointment to come and tour Edmo’s facilities.
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