I owned a VW Passat. The plastic window clips (the ones that actually hold the window to the track) kept breaking. After the second time I got online and did some research. As it turns out, this is a very common problem with this vehicle; an Audi part (made by VW) was virtually identical except made from metal. I bought these and they fit perfectly. Never had the problem again. Being a design engineer myself, it hurt my brain a bit on this one; if both autos were using the same part, buying twice as many (simplifying the obvious here) should bring the part to a cost point where a plastic one wouldn't be needed. Never underestimate the bean counters...
I had a similar issue issue with a 76 Datsun B210, the plastic had cracked vertically, fortunately the plastic piece was square so I removed the now two piece part rotated them 90 degress and reinstalled back in the sliding channel, as far as I know this lasted through my ownership and the two years my sister had it as well.
Zippi--excellent point. I do work with "additative" manufacturing and the choices for materials and processes expands each year. This technology is truly moving and moving quickly. There are still limits relative to component size but those are beginning to fall by the wayside also. You thoughts about minimal inventory are quickly coming to pass, which will be a boon for the automotive parts industry.
That's a really interesting insider perspective and not surprising, nyeng. I am sure that is a story repeated across many industries. Engineers do their job by thinking about what would work best and design products (cars, devices etc.) according to what would be the best material for the application. Then the number crunchers give them a budget and instructions for what materials are cost effective for the job. I am sure they often don't match up and you have to make do with what you can get! It must be frustrating sometimes.
I agree with Elizabeth. Plastic isn't necessarily 'bad' but it needs to be done properly. My personal opinion is that steel would be a better choice for that application giving the cyclical and shock loading as well as the temp extremes (windows are more difficult to move when the temp is below freezing).
As I've written before I worked as an engineer in the auto industry. It's all about cost. I didn't engineer parts to do the job at the lowest cost. Instead purchasing gave me a low cost part that fit their material cost reduction target and we had to engineer to work (as best we could).
Since you had to buy the window part it's obvious that the OE part lasted longer than 3 years or 36,000 miles. That's all GM cares about. In fact they don't want your car to last too long - they want you to buy another one. It's all short term thinking. I think the desire for fuel economy today might make this more of an issue. The desire for EPA number could drive more compromises in duraibility for the sake of light weight. About 3 years ago we were told GM would pay $1 per pound for weight reduction. Since we sold them a couple hundred thousand units per year it definitely got the bean counters' attention.
I view this from two sides. Since I make my living producing things from metal, mostly steel, I am somewhat amused when plastic parts fail. My industry lost thousands of parts, dollars and jobs to molded plastic parts so when they fail I can be smug about it.
On the other hand, I am a fisherman and have many reels with plastic gears that have never given me a moments grief, so I know properly engineered and manufactured, plastic can be a great substitute for metal. Some of the most expensive tackle is made from composites rather than aluminum, but I do not know if that qualfies as plastic.
A few years ago a plastic part broke in the mechanical timer of our old dishwasher. Took it apart and with my Dremel reworked the broken area and made it work again.
In spite of my technical repair skills, the wife was not pleased - what she really wanted was a new da*n dishwasher. A year later, when the top rack started falling off its rails and no parts available, I gave in.
Now the "new" (2 yrs old) diswasher is already losing broken plastic rack clamps.
Linear guides are one of the most important components required for the development of automated or computer-controlled equipment. Aluminum profile extrusions, used for these guides in machine design, can enable designed-in functional features.
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