New shop-Floor??

[bdrmachine]

I have a new metal (machine shop) 30' X 40' building on order. I would like some input on the concrete. I plan on using 2'x2' piers at the I-beam locations. In addition I'm going to have an 18" X 18" footer all the way around the slab. The slab will be 6" thick with 5/8" rebar on 16" centers. All concrete is 4000psi. Where the machining center will set (13000 lb machine) the concrete will be 12" deep in a 10'X10' area. Does this sound adequate, over-kill???

What are the pros and cons of bolting machines to the floor??

Thanks
Brian

[mxtras]

If it is a vibrating machine, put it on isolators and anchor it down.

If it is a precision machine, put it on fixators - like Unisorb. This way you can perfectly level it easily without pulling your hair out - if you have any left...

Scott

[One of Many]

6" should be fine up to 10 ton.

Does the OEM suggest bolting it down? Some machines do use the foundation as part of the structural integrity. If you must, just make sure it is on one section of concrete. Do not straddle cracks or expansion joints. The only other reason for bolting it down would be if the table weight limit was going to be an issue. For the most part it should support itself on swivel screw feet, leveling pads or shims.

DC

[ViperTX]

Why don't you have someone design you a post-tensioned slap for something better then 100 lbs per square foot. Tell them your application, sometimes the supplier of the building will recommend a particular slab for their buildings and its uses.

[Geof]

To take DC's suggestion a bit further; cast the concrete slab for the machine separate from the other slabs with a resilient separator strip all round and maybe take this slab even deeper than 12". I assume you are digging down to a firm footing and backfilling with packed gravel already. If you keep the machine on its own slab it is not going to be affected by other equipment vibrating.

When you are planning and building from scratch over-kill is impossible; you will always find something that is not adequate some time down the road.

[Dan the Tech]

One reason to place your machine on a slab that is separate from the rest of the floor is to isolate it from things like forklifts. You would be suprised at how far the floor bends as a forklift runs in front of it. You can see this effect with a precision level on the machine's table and then run a forklift in front of the machine. Bolting the machine to the floor will not cancel the effects of a bending floor. If you are cutting you will see the tool marks on the surface.

Isolation pads are also less affected by the cracks in the main floor. As the machine settles, it will loose its level. This will affect your machine's ways and precision. It may also cause undue wear in your way system.

Hope this helps.