Quote:
Originally Posted by JamesCH95
Can you please be specific about what those "many industries" are?
And AndyMark, an excellent company, supplies wheels almost exclusively to FRC (as far as I know they are not an OEM supplier to any manufacturer), and at $26/whack the performance wheels are far from cheap. The Skyway wheels (injection molded I believe) are less than half the cost with integral tread. If you were picking wheels for anything other than a 1-off robot you would definitely pick the skyway wheels over the "performance" wheels because they would be much more cost-effective.
Machining from solid chunks of metal is very costly because there is a large amount of wasted material and a lot of time is spent removing that material. These are both bad for your bottom line, and bad for your carbon footprint.
How many machines made in the real world use wheels machine from machined billet? Cars (including race cars), bicycles, airplanes, roller blades, skateboards, office chairs, commerical robots (i.e. packbot) etc. all seem to use wheels not machined from solid chunks of billet. Sure, you can buy car wheels machined from solid billet, but they're more expensive (by a factor of 2 or more) and heavier than forged wheels.
Machining wheels, or any part of reasonable size for that matter, from a solid material is typically found in 1-off, prototype, or development scenarios. I can't imagine these types of machines accounting for anything other than a very small fraction of any market.
|
You'd be surprised at the amount of production-run items that are fabricated in machine shops on milling machines.
Go to any local machine shop, and chances are 99% of the parts there aren't onesies and twosies for prototyping, but rather part of a 50, 100, 500, 1000, or 10000 part production run. Why?
Injection molding is cheap, but it's not a universal solution. It's good for cheap, low-tolerance stuff. But there are a lot of components out there that require high-precision, high-tolerance components in order to function properly. For these parts, they are often fabricated in machine shops. But because these products are often industrial-to-commercial/industrial or industrial-to-military parts, you won't see them in Walmart anytime soon. But these products do exist, and they do keep machine shops humming.
But precision isn't the only reason that machine shops remain in business; often times injection molding or sandcasting is much more expensive than milling out of billet stock if you're talking about low-volume or intermittent product runs. Injection molding has a lot of tooling and setup costs, and doesn't become cheaper than milling until you're made quite a bit of parts.
And even then, a sizable chunk of business I've seen at a local machine shop was taking forged/sandcasted parts, and then milling critical features into it, like facing off flange surfaces, drilling and tapping mounting holes, etc.
Besides, there isn't that much of a waste from machining out of billet stock; the chips get recycled. That, and (without seeing numbers) I'd rate machining stock out of aluminum much higher than plastic injection molding on the environmental/CO2 scale. The former is infinitely recyclable and does not need petroleum as a basic ingredient, whereas the latter can only be "downcycled" a few times and needs petroleum-based hydrocarbons as a basic ingredient.
P.S. This post was typed up on a MacBook Pro computer, which has its entire frame/case milled from a billet of 7075 aluminum.