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I had the delightful experience of a couple of product failures today. Just thought I'd pass along a couple of observations from the field.
First - while doing some gardening, my wife called out that the washing machine had just died. We had some work done it under warantee about 5 months ago. The machine is a front-loading design by Frigidaire. The front-loading designs use less water, and therefore less detergent, so are preferable where water is expensive or where the discharge goes into septic systems. However, these designs have a greater repair and failure rate than top-loading designs, and I found out why.
I went into the garage to check it out. I noticed that the tub had fallen and the gasket had twisted, which indicated structural failure. First, Frigidaire uses screws with square holes in the heads, so I had to use my socket screwdriver with the right bit. I removed the panel and confirmed the tub had fallen. I then looked at the suspension system and found that one spring had failed. Further examination revealed that one of the damping struts had also failed. The machine was hosed. Being a Frigidaire and on a Sunday, I was not going to find the parts. Being an engineer
, I saved the spring parts.
My wife was thoroughly pissed because of the continuing problems with this machine, and she wanted a new dryer anyway, so we went to Sears to buy a new washer and dryer. The cost was $1500 with a 5 year service agreement on the washing machine, which it turns out is a Frigidaire built for Sears under the Kenmore label. Kenmore however has a better reputation, and at least, we can get servicing done faster and at lower cost.
So we returned home and I tried to jerry-rig a support system - basically a brick wrapped in a towel under the tub frame in the rear, and a 4x4 in the front. Well that worked well until the final rinse. The final rinse is high speed (don't know the rpm's), and with an 'unbalanced' load, which is inherent in the front-load designs, the tub vibrates. Well, I had to hold down the washing machine while holding the 4x4 while the tub bounced up and down. No wonder the spring failed, it was subjected to periods of low-amplitude/high-amplitude cyclic loading - a recipe for failure at relatively low cumulative cycles.
The problem could possibly be poor installation procedure in the factory, which leads to a vulnerability in a high stress/fatigue environment. In the upper hook, the spring failed at the middle of the 'C'. There appears to be a slight depression on the inside curve of the 'C', and at the top of this depression is the location of the initial site where a flaw propagated across the diameter of the spring (perpendicular to axis of spring wire). The fatigue pattern is classic from the flaw outward in a fan shape to about the central axis of the spring wire. From there the fracture surface is about 30° with respect to the spring wire axis in the center core of the spring, and 45° near the OD (as is expected in classic ductile shear failure). There is some bending indicated also. I hope to find a microscopic camera somewhere, preferably a Materials Science lab to get some closeups.
I suspect the depression on the inside curve of the spring hook was made during installation, when the spring is stretched to put in place - a cross brace in the frame of the washing machine. While trying to hold down the washing machine and hold steady the tub during the high speed final rinse, I got a good feel for the high loading on the spring. The failure of the damping strut also contributed to problem.
Second - As for the second product failure, I was using a pick with a 36" head to remove some tree stumps (when I was interrupted to deal with the failed washing machine). I was trying to pry up a root when the pick handle broke. The break occurred just below a plastic fitting on the head of the wood handle. The plastic fitting is fastened to the handle (probably by adhesive - I haven't opened the failed handle yet), and it provides an interface between the wood handle and metal tool head. The plastic handle provides an area which is somewhat impact resistant if the user misses the objective and accidentally hits the handle, it reduces the stress on the wood, and it reduces the wear from the metal tool head.
However, I noticed that the wood handle was scored just below the plastic - possibly something that happens during manufacture or perhaps during shipment(?). When I bought a new handle ($11), I noticed a similar scoring pattern. This scoring pattern undermines the structural integrity of the handle. So I will see how long it lasts. The store clerk suggested that I keep the purchase receipt and if the handle breaks, I can return it and receive a free replacement ( ). I'll probably need one next year.
First - while doing some gardening, my wife called out that the washing machine had just died. We had some work done it under warantee about 5 months ago. The machine is a front-loading design by Frigidaire. The front-loading designs use less water, and therefore less detergent, so are preferable where water is expensive or where the discharge goes into septic systems. However, these designs have a greater repair and failure rate than top-loading designs, and I found out why.
I went into the garage to check it out. I noticed that the tub had fallen and the gasket had twisted, which indicated structural failure. First, Frigidaire uses screws with square holes in the heads, so I had to use my socket screwdriver with the right bit. I removed the panel and confirmed the tub had fallen. I then looked at the suspension system and found that one spring had failed. Further examination revealed that one of the damping struts had also failed. The machine was hosed. Being a Frigidaire and on a Sunday, I was not going to find the parts. Being an engineer
, I saved the spring parts. My wife was thoroughly pissed because of the continuing problems with this machine, and she wanted a new dryer anyway, so we went to Sears to buy a new washer and dryer. The cost was $1500 with a 5 year service agreement on the washing machine, which it turns out is a Frigidaire built for Sears under the Kenmore label. Kenmore however has a better reputation, and at least, we can get servicing done faster and at lower cost.
So we returned home and I tried to jerry-rig a support system - basically a brick wrapped in a towel under the tub frame in the rear, and a 4x4 in the front. Well that worked well until the final rinse. The final rinse is high speed (don't know the rpm's), and with an 'unbalanced' load, which is inherent in the front-load designs, the tub vibrates. Well, I had to hold down the washing machine while holding the 4x4 while the tub bounced up and down. No wonder the spring failed, it was subjected to periods of low-amplitude/high-amplitude cyclic loading - a recipe for failure at relatively low cumulative cycles.
The problem could possibly be poor installation procedure in the factory, which leads to a vulnerability in a high stress/fatigue environment. In the upper hook, the spring failed at the middle of the 'C'. There appears to be a slight depression on the inside curve of the 'C', and at the top of this depression is the location of the initial site where a flaw propagated across the diameter of the spring (perpendicular to axis of spring wire). The fatigue pattern is classic from the flaw outward in a fan shape to about the central axis of the spring wire. From there the fracture surface is about 30° with respect to the spring wire axis in the center core of the spring, and 45° near the OD (as is expected in classic ductile shear failure). There is some bending indicated also. I hope to find a microscopic camera somewhere, preferably a Materials Science lab to get some closeups.
I suspect the depression on the inside curve of the spring hook was made during installation, when the spring is stretched to put in place - a cross brace in the frame of the washing machine. While trying to hold down the washing machine and hold steady the tub during the high speed final rinse, I got a good feel for the high loading on the spring. The failure of the damping strut also contributed to problem.
Second - As for the second product failure, I was using a pick with a 36" head to remove some tree stumps (when I was interrupted to deal with the failed washing machine). I was trying to pry up a root when the pick handle broke. The break occurred just below a plastic fitting on the head of the wood handle. The plastic fitting is fastened to the handle (probably by adhesive - I haven't opened the failed handle yet), and it provides an interface between the wood handle and metal tool head. The plastic handle provides an area which is somewhat impact resistant if the user misses the objective and accidentally hits the handle, it reduces the stress on the wood, and it reduces the wear from the metal tool head.
However, I noticed that the wood handle was scored just below the plastic - possibly something that happens during manufacture or perhaps during shipment(?). When I bought a new handle ($11), I noticed a similar scoring pattern. This scoring pattern undermines the structural integrity of the handle. So I will see how long it lasts. The store clerk suggested that I keep the purchase receipt and if the handle breaks, I can return it and receive a free replacement (
). I'll probably need one next year.
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