Your Refrigerator is not Really Breaking Down after the Warranty Period

Use Minitab for Warranty Prediction

abandoned fridge

Your Refrigerator is not Really Breaking Down after the Warranty Period

I need to get a few things off my chest regarding product warranty period misconceptions.  I often get together with my friends on the weekend over dinner and drink when all of a sudden one of them breaks into a tirade of don’t buy this brand, they suck!  When I try to qualify that with them and ask why, I’m almost always told the following, “They tried to sell me an extended warranty at the store for x dollars but I declined.  The fridge was warranted for 12 months but it broke after 13 months!”

“Those bastards!  They always design things to break right after the warranty period expires!” I usually sit shaking my head in amazement at these assumptions.  None of my friends are neither electrical nor mechanical engineers and I always explain to them how this is just not true.


When I whip out a pad an pen and begin to explain the bathtub curve, which is probably the easiest way of explaining reliability engineering, they sit as awestricken as I did when they made their bold claims about products being designed to stop functioning after a short while.

old broken down fridge

There is no Warranty Period Conspiracy!

As I explain, “When engineers design consumer grade products the goal is to design the lowest cost product that will far exceed the normal expected functional lifetime of the product.” This indeed is the best marketing wouldn’t you think?  A product that has a 12 month warranty that works as expected 8 years later (but maybe stored in the garage) says something about a brand.

I further explain that the first major hurdle in any design and probably just as important as ensuring the lowest cost and longest functional lifetime is to design a product that will not fail during the break-in period of the product or first number of days. The number of days here can be as little as a week or up to about three months.  Product failures that occur very early in their lifecycle (or warranty period) are called break-in period failures or infant mortality failures.  Much has been written about this elsewhere regarding hard drives, computers, and the automotive industry.  These failures usually don’t occur in the same way as in critical systems such as avionics system or the aviation industry, medical equipment, and military system as these are product industries strong in regulation that ensures robust preventive maintenance plans.

To further demonstrate the effect of early product failures against normal use failures and eventually to the end of their normal use period, usually referred to by reliability engineers as the wear-out period, I refer you to the bathtub curve.

Thanks for reading.

Reprinted with permission from

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