Be aware that LED exposure units have a very narrow nanometer (nm) range when used with dual-cure emulsions and most are not in the range best suited for dual-cure. Metal halide units have a broad, forgiving range that runs from approximately 360 to 410 nm.
That being said, if you do not use dual-cure emulsions, LED units offer some distinct advantages:
- The bulbs on LEDs will last in the neighborhood of 50,000 hours with no noticeable light degradation. The light is as good on the first second as it is at the end of its life. Metal halide bulbs begin to degrade from the first time you use them and weaken with age. So, at some point, you may have to increase your exposure time by a minute until you decide to put in a new bulb.
- LEDs use very little power compared to metal halide. When using an LED, you might be looking at 5 or 6 amps per usage as compared to 12 amps with metal halide.
- LED units feature instant on and off, while metal halide units have to warm up before fully functional. For this reason, many shops leave metal halide units on all day to reduce wait time. With LED units, no power is consumed between each usage, and there is no wait time. This also lessens its overall power consumption.
If you use a dual-cure emulsion, a metal halide provides a sharper image than an LED. However, unless your shop prints highly detailed artwork, this additional quality may be overkill.
An LED unit is best used for short, fast runs with a lot of setups and teardowns. An LED paired with a photopolymer may be faster than a metal halide when doing this type of work.