plastic reflector in combination with 25W bulb?

[PerKr]

I've been given the task of trying to fit an existing lamp into an existing component. I have been told to just make it fit, meaning that I may modify component carriers which were previously sacred. Now that it seems I have found a solution for the bulb (and socket) to fit there is the problem of designing a reflector. There isn't much space available, so it isn't unlikely that the bulb would come in direct contact with the reflector. Additionally, the space available might not allow the use of a simple design (the reflector originally used with the lamp I'm designing for was basically a U-shaped metal piece), which is why I'm considering a plastic reflector.

So, would a plastic reflector work with my requirements (25W bulb, probably in direct contact, active in periods of 10-15 minutes if we're unfortunate)?

(oh yeah, it's for use as an external lightsource for household refrigerators and freezers, if that information is of any help)

 

[patprimmer]

Plastic reflectors are in wide use in automotive lighting.

A critical question is what temperature is it likely to see.

A suggested material based on the very little necessary information provided would be white coloured glass filled PET or chrome plated PC/ABS alloy.

If you can avoid direct contact by even a mm or two the job will be a lot easier.

Regards

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[Pud]

I think that car headlight reflectors (halogen/xenon discharge) are made from plated PPS.

As Pat suggested, a lot depends on bulb temperature.


Cheers

Harry

 

[CoryPad]

Most car headlight reflectors are made of bulk molding composite - a thermosetting saturated polyester resin reinforced with glass fibers. Some thermoplastics are being considered for future programs.

Regards,

Cory

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[Pud]

Or polyarylamide:

http://tinyurl.com/6gtb5h

Cheers

Harry

 

[patprimmer]

His application is 25 watts, not twin bulbs at about 50 or 60 watts each. I agree BMC will have the best heat resistance. The thermoplastics with those temperature ratings will be very expensive.

The OP does not state whether he requires an accurately focused reflector or just more light going in the genera direction of in front of the light. This will impact on required dimensional stability and colour and surface finish and scope to design reflector shape for focus or for clearance on the bulb.

We need a some more info from the OP to give good advice, especially temperature reached and quality of light beam required.

Regards

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[PerKr]

I need as much light as possible going in the radial direction of the bulb, towards the floor (the lamp is mounted so that its axis is parallell to the floor). The lamp which is supposed to be replaced is a 25W halogen spotlight ("decospot" something or other) and though I'm convinced we're not going to get as much light from the cheaper bulb, I don't want to make it even worse by adding a poor design either.
The typical appliance is about 175 cm from floor to lamp. It is 60cm wide and the lamp is 15 cm from the right-hand side (as seen from the front of the appliance).

The temperature reached is a bit uncertain, but I'll check with our laboratory staff to see if they have any information.

 

[patprimmer]

The temperature reached is a critical piece of information

Regards

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[PerKr]

I found a measurement for a similar lamp, though the housing used was better ventilated and provided more space. it seems I should consider temperatures of at least 130°C (the maximum temperature reached during the test with that other housing).

 

[patprimmer]

Glass filled PET will be good to 160 deg C

Regards

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Please see FAQ731-376 for tips on how to make the best use of Eng-Tips Fora.