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which uv curing lamp should I buy for big surfaces

Posted by joepuma 
which uv curing lamp should I buy for big surfaces
July 16, 2010 07:06PM
Thank you in advance for any information about curing lamps.

I saw the Loctite video on youtube and they use a 500 Watt curing oven in the demonstration. The pieces of acrylic are joined to the point where the acrylic will snap before the joint.

I want to join larger sheets of acrylic than can fit into this 500 watt oven. C R Laurence has a high intensity hand- held uv lamp that has 250 watts.

Will this be enough to get a clear strong bond like the Loctite oven?

Many thanks,
Re: which uv curing lamp should I buy for big surfaces
July 29, 2010 02:13AM
I would imagine a 500W UV lamp could be quite dangerous not just to your eyes but also on any exposed skin. I also dont quite understand why they would use UV to join acrylic? Do you have a link to the video? Maybe it was just a 500W conventional oven that was used?

You could even do away with the oven all together and try some other methods for joining the acrylic such as solvent welding.

Would I be right if I assumed your question is not reprap related?

Re: which uv curing lamp should I buy for big surfaces
July 29, 2010 09:17AM
Hello Capo,

I am a model maker and I am very familiar with the solvent to join acrylic. The problem is that the solvent leaves ugly air bubbles.

A fellow model maker has the loctite oven which has a 500W or 1000W bulb in it. If you follow the link you will see that the loctite oven will glue the acrylic totally clear with the joint stronger than the material.

The second link is to a video with a handheld UV lamp that has 250W bulb. This UV light also provides a clear joint. I just wish I could see how strong the joint is afterwards.


Re: which uv curing lamp should I buy for big surfaces
July 30, 2010 11:36PM
Interesting videos, thanks for the links. I had no idea that UV reactive adhesives could be cured so quickly.

In the first video it appears they are using loctite 3941, data sheet on it here. The wavelength needed to cure the adhesive is 365 nm which is good news because its the wavelength produced by most common 'black lights' and is also the safest (low energy) UV.

As for how many Watt's your globe will need to be all depends on the depth of cure and its size. If your just pressing two sheets of acrylic together like in the video then I would assume a thin bond of only a few mm. According to the data sheet this requires around 10-20 seconds to cure at an exposure of 100mW/cm.

So the next question is what globe gives 100mW/cm at a workable distance of say 10cm? A few quick calculations show that small and large florescent black lights put out a lot less than 100mW/cm at the surface of the globe, let alone at a 10cm distance. So these may work but the curing time might be considerably longer. Eg:half an hour. UV LED's may be a possibility and looks like they can be bought quite cheaply on ebay too. The LED's in the link have a peak output at 400nm so are not perfect but will still put out some light at 365nm. If you made an array of UV LED's placed very close to the adhesive it could be enough to cure it in a reasonable amount of time.

If you do still want to go down the 500/1000W globe path like in the video then curing really large objects may become a problem. The fall off in power with distance (inverse square law) of the UV lamp may become a real problem leading to uncured adhesive at areas furthest from the lamp. However this is easy to solve by using multiple globes in an array or moving a single globe over the surface at a slow speed. But I still think the LED array would be a more elegant solution.

Hope that's of some help. Oh and if you do build something that works be sure to post here with some photos as a similar setup could be adapted for reprap related projects.

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