Material Failure Rate vs Cost of doing BusinessHops,
sorry it took me a bit to read the thread (and refrain from laughing). Yes, there is a way to determine the average life of a fuse. The problem with defining a 2 year fuse is when they test the MTBF, they are running current through the fuse 24x7 during their testing cycle, where the actual fuse used in your laptop might not see the same enviornmental variables. Do you turn off your laptop? Do you move it around your house, depending on what you are doing at the moment? Does your electric company keep your house fed at a constant 120v (or 2/3 phase if you are in a big enough building.. Yeah, RIIIGHT). Your fuse could last longer or shorter for the same reason. No one can determine when it will fail. Ever heard of a "lemon"? Yes, lemons can bring the average MTBF down if you get a few products fail prematurely. Those can be caused "average" the time of failure. Lemons are expected of all electronic products, which is why you see warranties on most electronics for at least 30 days.
You are most likely not going to run your computer 24x7 in a lab enviornment (dust free, temperature controlled, etc).
With that said, it depends on the materials used in the fuse. Parts made mostly of raw material (contains ions with physical material) will not last as long as a refined material (most ions are removed and you have a greater amount of the actual material, for example Copper).
I can give you an example of this, with things like copper tubing (for heating pipes) versus copper wire. Both are labeled copper, however the wire material costs more because the wire has to be stripped of all ions (and nothing will be perfect, but they can eliminate a majority of any other metal's that would cause interference on the wire). Your copper heating pipes do not need to be refined as much because you are not passing electronic current through the copper, but rather using the qualities of copper piping to transfer heat throughout your house.
With that said, raw material are traditionally cheaper than refined materials (hence the reason not all fuses or any part for that matter are have the same identical price). Hospital equipment needs higher quality parts for obvious reasons, be it fuses or switches or anything for that matter. It would be interesting to see a product like a heart monitor just go down due to a cheap part being installed originally. Then the fall out from that could be a loss of business in the future if word spreads quickly that a Heart Monitor company puts cheap parts in their equipment. Think of the famous tire company called "Firestone". How about Ford's SUV's using their tires? Yeah, both Ford and Firestone took a hit from that because of word of mouth (and News Media). Most manufacturers do not want to have to replace cheap parts regularly, so they use what they feel can get them the longest life of the product and still keep their costs down. Yeah, they have light bulbs that are over 100 year old that still work (One of Edison's light bulbs is still around I think, correct me if i'm wrong). Of course a 1 Watt bulb will last forever...
With all this said above, I am tired and going to bed (3 hours of sleep over last two days. I hate projects that don't go according to plan and letting idiots be involved in planning stages). Just remember you can say the MTBF is 2 years, doesn't mean it will go that long (or short). Enviornmental variables play something like 80% of a factor in the failure rate of products.
oh, and for those of you wondering my credibility, I have a Mechanical Engineering degree with a computer science minor. Don't hold anything against me