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Casting vs Weldments vs Bolted Structures
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Posted by: FarrOut

03/31/2005, 14:03:11

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Hey all...

I am currently designing a high speed 3 axis pick and place transfer system, and I need some help.

Due to the fact that I am using servo-motors to move all 3 axis of movement, inertia is a big issue, so every component must be light weight. So I started the concept of my design using aluminum plate, bolted together, to create thex, y, and z carriages. As I got into the design of the machine, I started to wonder if I could save even more wieght and still have the strength if I cast the main carriages / components.

So now I'm doing my research, and since I'm not too familiar with casting, I thought I would ask here.

1. Can anyone point me towards some good literature, books, or internet resources so I can learn more on this subject?

2. Since this is a prototype machine, and basically every design after this one will be somewhat different, I would assume that one off sand casting will be the only solution. Now I realise that casting will be more expensive than a bolt structure, but is the final cost going to be so enormous that I shouldn't even be looking at casting as a solution?

3. Is there job shops that will manufacture on-off castings in small amounts? If so, do I have to provide them with just the design of the part, and they will take care of the rest, or will I have to also design the casting molds etc?

4. Will a casted component hold up to the high dynamic forces, shock loads, vibrations the same or better to a bolted aluminum plate structure?. I am worried about cracking etc.

5. Please let me know of ANYTHING that I may be missing or misunderstanding.

Thanks in advance

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Re: Casting vs Weldments vs Bolted Structures
Re: Casting vs Weldments vs Bolted Structures -- FarrOut Post Reply Top of thread Forum
Posted by: randykimball
04/01/2005, 23:46:53

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Two suggestions:
1.Machine out of aluminum bar leaving webs / ribs.
2.Sand casting.
1.There are plenty of books at on-line book stores.
2.No, not so expensive. About the same as to machine out of aluminum bar. Prototypes are often done this way.
3.There are lots of sand casting shops around the world. You can often simply provide a wood model of the shapes and get back an aluminum copy. They will use the wood model to form a sand mold. They will have to add a spru and runners, this will cost a little.

I often make prototypes out of plastic because it is so easy to machine and has "similar" properties to aluminum within reason if you allow for strength and temperature difference.
I use HDPE or UHMW... High Density Polyethyene ... Ultra High .... . They come in blocks, bars, sheets, tubes, .. you can get them from most plastic vendors.

The worst suggestion of your lifetime may be the catalyst to the grandest idea of the century, never let suggestions go unsaid nor fail to listen to them.

Modified by randykimball at Fri, Apr 01, 2005, 23:51:22

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