one for the boffins
- Thread starter Wazz-1
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Soldato
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slightly less than 2kW?
not without the efficiency - you need to know how much of that energy is being dispersed as thermal energy and how much is going into lighting the bulb. IIRC filament bulbs are about 5% efficient, which means about 95% of the power will be heating up the bulb and only 5% producing light.
In short no.
Wow Thanks guys more boffins than one could shake a stick at.
I will try and explain my problem, I work as an engineer in a can factory, we apply a lacquer to the inside of a tin can over the welded side seam to protect it from various aggressive products put in the can. The lacquer has to be cured at a temperature of 250c we currently do this by passing the can through a conveyor under infrared lamps taking 12 seconds to complete a pass through, this however does not cure properly, I cannot extend the conveyor, I cannot slow down the conveyor and I cannot use more lamps only increase the wattage. I can measure the temperature with a thermometer and know it can reach far in excess of 250c, I can also measure the temperature of the can, the can only reaches a temperature of 200c/230c. This was done with 5 x 1000 watt infrared lamps, I now have 5 x 2000 watt lamps yet the can only reaches 200c/230c. does this suggest the lamps become less efficient at a higher wattage? Surely not to this extent?
I will try and explain my problem, I work as an engineer in a can factory, we apply a lacquer to the inside of a tin can over the welded side seam to protect it from various aggressive products put in the can. The lacquer has to be cured at a temperature of 250c we currently do this by passing the can through a conveyor under infrared lamps taking 12 seconds to complete a pass through, this however does not cure properly, I cannot extend the conveyor, I cannot slow down the conveyor and I cannot use more lamps only increase the wattage. I can measure the temperature with a thermometer and know it can reach far in excess of 250c, I can also measure the temperature of the can, the can only reaches a temperature of 200c/230c. This was done with 5 x 1000 watt infrared lamps, I now have 5 x 2000 watt lamps yet the can only reaches 200c/230c. does this suggest the lamps become less efficient at a higher wattage? Surely not to this extent?
Radiative heat lamps heat things by direct absorption of radiation, rather than heating the air like an oven and different types of heat lamp bulbs put out their energy at different wavelengths, it could just be that the lamps you are currently using don't emit strongly at the appropriate frequency for the lacquer to absorb it and heat up enough to cure.
Of course I could be totally off on this, I'm not a heat lamp/curing expert
Of course I could be totally off on this, I'm not a heat lamp/curing expert
Soldato
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Get some 5K fresnels on the go! They are some hot and blinding mofos!
You know what? I hate that word. The Sun uses all the time and it give off a whiff of reverse snobbery.
I would go with something like: Materials have a certain heat capacity and Thermal conductivity. Thermal conductivity is a constant for any material http://en.wikipedia.org/wiki/Thermal_conductivity#Equations
If you've doubled the power of the lamp and the can is still the same temperature it means either:
1) The can/laquer needs more time to get up to temperature. It's Thermal conductivity means that it's taking on as much heat as it possibly can within the timeframe available.
2) You need to increase the wattage of the lamps significantly to induce a massive thermal gradient (1KW to 2KW isn't a large enough difference in heat from the ambient temperature of the can/laquer)
3) You need to alter the angle of the can with respect to the bulbs in order to get the optimum cross sectional area. I image with the way in which the machine is set up, this will yield little benefit.
4) Make the can/laquer thinner (probably impossible)
I may be way off the mark but that sounds plausable!
If you've doubled the power of the lamp and the can is still the same temperature it means either:
1) The can/laquer needs more time to get up to temperature. It's Thermal conductivity means that it's taking on as much heat as it possibly can within the timeframe available.
2) You need to increase the wattage of the lamps significantly to induce a massive thermal gradient (1KW to 2KW isn't a large enough difference in heat from the ambient temperature of the can/laquer)
3) You need to alter the angle of the can with respect to the bulbs in order to get the optimum cross sectional area. I image with the way in which the machine is set up, this will yield little benefit.
4) Make the can/laquer thinner (probably impossible)
I may be way off the mark but that sounds plausable!
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Move the lamps closer to the conveyor? Slow the conveyor belt down so the cans have a longer period of time to heat up and reach 250 degrees C
Any way you can move the lamps closer or use reflectors to focus the energy on the cans better?
Sounds like you're trying to cure a coating on the inside of a can with lamps shining on the outside? This could be very inefficient as the shiny outside of the can will be good at just reflecting the infrared radiation away. Is there any way you can direct the radiation inside the cans? Reorient the cans maybe?
Do you have the optimal wavelength of infrared lamp for your coating? If your coating is water based, for example, using near infrared lamps will be ineffective - you need to use medium wave infrared for that.
Sounds like you're trying to cure a coating on the inside of a can with lamps shining on the outside? This could be very inefficient as the shiny outside of the can will be good at just reflecting the infrared radiation away. Is there any way you can direct the radiation inside the cans? Reorient the cans maybe?
Do you have the optimal wavelength of infrared lamp for your coating? If your coating is water based, for example, using near infrared lamps will be ineffective - you need to use medium wave infrared for that.
Not sure if I'm a boffin but here it goes
Things to consider.
You aren't just heating lacquer you are heating lacquer and can this will take longer.
Your lacquer may need time to cure , does it just need to hit x temp or does it need to mantain that temp.
As someone mentioned focusing and angling of lights or products may be an answer, I would also imagine placing a reflective layer around the inside of the machine and on surface of conveyer belt may reduce overall energy absorbed by insignificant entites.
Things to consider.
You aren't just heating lacquer you are heating lacquer and can this will take longer.
Your lacquer may need time to cure , does it just need to hit x temp or does it need to mantain that temp.
As someone mentioned focusing and angling of lights or products may be an answer, I would also imagine placing a reflective layer around the inside of the machine and on surface of conveyer belt may reduce overall energy absorbed by insignificant entites.
Just a word mate no disrespect, I'dont read the sun, its what my boss calls someone who knows more about a subject than he does
@ Haggisman
yes 23 years in the business and 40 years young in may (WooHoo life begins at 40) and i still have home work
@ pre1twa
cant do either, the unit is part of a production line.
@ Malc
sound advice but i have the weld seam running parallel with the lamps
Unfortunately we have to stick to a minimum film weight for the lacquer to be effective.
@Liampope
Lamps are as close as i can get them to the can, although the reflectors are a bit crap, i was advise to fit gold color reflectors.
Yes as advised by the lacquer manufacturer
Thanks for all your input guys, I think i will be suggesting we move away from this setup to an induction oven, i believe we would have much more control with a direct heating of the can itself .
The lamps may be slightly less efficient (or slightly more) at higher power ratings but this doesn't really resolve your issue.
If your goal is to have the lacquer harden and you don't directly care about heat production then I would look at the actual curing process of the lacquer.
What you might find is that there is a an amount of time required at a certain temperature needed to cure. Increasing the heat may not resolve any issue. You need o contact the manufacturer of the lacquer, or investigate alternative solutions.
You might have to invest in an industrial oven so the cans can effectively bake for 1-2 hours (or maybe just 5 minute etc.). 12seconds might not be enough for most regular lacquers.
You might find that passing the cans through the heater multiple times does the trick.