Vacuum Fixture on a palletech system.

[DC Gorn]

When I ordered my i700/palletech system I asked if I could have a vacuum port in the table. After some deliberation on Mazaks part they said there was just no place for the required rotorary coupler,

Now I am working on adding a part that really should have vacuum fixturing. Has anyone tried or know of anyone building vacuum fixtures that do not need to be connect to vacuum at all times?

 

I am thinking I would need a “reservoir” (tank) built into the fixture. 
I am thinking I would want a redundant system to make sure the part did not fall into the machine or the automation if vacuum was lost.
I am also thinking of a spring loaded mechanical vacuum indicator that I could probe to verify the presents of vacuum in the fixture.

Any thoughts or ideas? Any good vacuum fixture componet suppliers? 

 

Thanks in advance.

 

[crazy^millman]

Can I throw this out there as food for thought. Internal self positioning and adjusting spider to support the part? Then go with left spiral endmills that will force the thin part into the fixture verse lifting off that right hand spiral tools normally do? Just purposes this to a customer who rejected the idea because they felt it was to much engineering up front. They are on their 4th process and still have no produced a good part. My suggestion was 2 operations for a part where they spent a little more on raw stock and got it a 1/2 thicker. They then drilling and tapped holes to sandwich the part in between 2 plates supported and located to the table. Prep operation was a dovetail. Now you machine the complete inside of the part finishing everything. 2nd operation fixture is some engineering, but you make an internal spider concept fully supporting the part. To finish you use left hand spiral tools forcing into onto the fixture and you get no chatter and hold the .005 profile tolerance and the .002 true position this part has with its .03 wall thickness and done. Oh this part had undercut and raised internal ribs so would have not been an easy 2nd operation fixture, but in my thought would have been the best way on that project. Maybe your project could use this idea to get around the vacuum?

[DC Gorn]

 Internal self positioning and adjusting spider to support the part?

 

What is that? The best way to descried the is if you took one of those old steel folding chair and took just the seat and cut off the rolled lip all the way around. Adding material is not an option as the material is very expensive composite. I need to trim all the way around the chair seat and I will need to do a small amount of surface work to the top. So I need 360 degree access. Other limitation is I can only use one pallet, If I where to go to 2 ops they will need to fit on one pallet.  

 

No problem doing the upfront engineering. I started my career doing production fixture design and even some automated fixtures use in the fully automated Caterpillar machining cells 20+ years ago.

 

 

I also have other flat parts that are large and need trimmed all the way around so if I can figure out the vacuum fixture then it can transferr to other part numbers.

[crazy^millman]

How do you machine a bell? You must use a internal support to damper the part. The problem is a bell is a casting or a forging that is never the same so a solid shape is out of the question to go inside of the bell. Most time only the outside of a bell is machined so they figured out to machine something meant to create sound you had to deaden the bell. A solid shape would be perfect, but again not practical so a multi-leg shape with fingers or points on the end almost like a spider would be the best compromise. Natural things can be used when creating a fixture and if you had something that was adjustable and supporting at the same time to go up inside of the part that dampened the part, supported and located the part then your problem is solved. Engineering 101 you must engineer a solution to your problem and sometimes the easiest method is n the most practical method. When this is the case you have to think out of the box. I had a mould I needed to make years ago for a part. Problem was I needed sharp corners and getting the shut off the way I wanted was not easy. I made a puzzle out of the mould where the 1st piece was one side and a corner, the next piece locked and located on the outside and created the next face and corner. So I went through designing the mould for this part. Once it was all said and done it looked like a block, but was made up of 8 pieces. You have the shape of a chair seat it would lend itself to a internal piece that expands and maybe an insert locks into one of 4 corners. That creates the tension needed to hold the shape? Now you have 4 locating holes that now slide onto 4 ball lock pins. The turn f a set screw or a valve and that drives the pin up into the ball bearings that pull the 4 interlocked plates down. Maybe you get real creative and make them on a cam and can tension theart less or more from that point. Get creative and solve the engineering puzzle. Got a family of parts them make the internal adjustment process a common shape that outside support shapes can be added to. Seems to me you need to over come a couple issues. Solve those issues using out of the box thinking. The from there you have a process that gets away from needing the vacuum. I love to use a vacuum, but if is not practical then make and come up with something that is practical.

 

Now if you are making 5 parts none of the above may be pratical, but if you are making 5000 then it may be pratical. The other part of the engineering equation does the work warrant the process to support the work needed? Has someone upfront or above you understood the work needed to make it happen. I love it when people go get all this work by quoting insane run times. Can you help us program this part? Yes we can. Okay we only quote 1 hour to make this part and your program has to make it one hour. Sorry that is a 3 hour part. Well we didn't quote it that way. Then we are not the right company to help you. You have been given a project that you know what is the best most effective way to accomplish the task. Problem is you may not have that have that method to use. Thus you came in looking for alternative method and I hopefully gave some good food for thought.

[taperlength]

The trouble with vacuum fixtures is they always leak a little or a lot.  So if there is just a reservoir and no pump, the amount of vacuum is always degrading over time.

[Newbeeee™]

Surely there's somewhere to add a coupler into the base/side of the fixture and run a coil airhose (like the lorry trailers have)? 

Providing the index rotations are controlled (ie 0 > 180 then back again rather than spinning right around) and the coil hose is zip tied accordingly away from spindle and table, then this would work?

I'm assuming that you won't run this unmanned and on an auto pallet shuttle - you'll have to have operator disconnect before pallet change?