Time to build a machine to automate a process, Anyone want to help my first journey? - Page 5
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  1. #81
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    Quote Originally Posted by CosmosK View Post
    No. Cheap crap for non essential motion. They aren't even much cheaper than real bearings.

    There most certainly are companies out there there build dedicated drill only machines, but they won't be cheaper than another (new) Robodrill.
    Igus isn't cheap crap, ive used their bearings for all sorts of stuff and they work great.

    Quote Originally Posted by Milland View Post
    So no love for the idea of using a horizontal indexer in the original machine along with one or two powered horizontal drills to add the side holes? I still think that's worth looking into for a "done in one" option if molding isn't a good path.

    For operator fatigue, add some low-cost cylinders to the doors to open and close them (with appropriate safeties) , and maybe an in-machine air blast to clean the fixturing before part removal. If this part must be machined do it in one setup and if the process is made simple enough perhaps a robot un/loader can be added.
    We have fast robots on site and they just aren't as fast as a human. The one and done option eats up too much CNC spindle time with the downtime of loaf and unload. A 2ndary specialized machine is the way to go I'm afraid. We don't have a horizontal mill which really would be the way to go.


    Quote Originally Posted by Robert R View Post
    Years ago I worked at a company that used the plastic lined metal shell bearings running on 2 inch diameter Thompson case hardened centerless ground bar in a vacuum chamber. It was a elevator that cycled and then did a rotary index once every 5 seconds 24 hours a day six days a week. The bearings required no oil and did not generate any debris while sliding. One of the machines was disassembled for repair after a few years of service. The plastic bearing sleeves showed very little wear. The plastic sliding materials have improved since then.
    Keep in mind that these bearings need to be kept away from dust or shop grit. If contaminates get trapped between the plastic liner and the shaft they will fail. The same is true of any other bearing design.

    In looking further at the geometry of the cassette part feed it has become apparent that the design is limited to two drill stations. The elevator ,cassette, and push in bar occupy the 12 o'clock position. The part return push bar occupies the 6 o'clock position. The drill heads are at the 3 o'clock and 9 o'clock positions.
    It is possible to overcome this limitation at the expense of a much more complicated part transfer from the cassette to the drill station. It is not worth the trouble.

    The prototype cassette is made up with four 37" long 3/8 diameter bars with threaded ends. The bars screw into a wide base square aluminum block with tapped holes at the four corners. At each bar a aluminum standoff 1.20 inches tall with a 3/8 bore is dropped down. A.06" thick aluminum plate with four holes is dropped down next to form one shelf. The stack is repeated for all 30 shelves. The idea is to limit the cassette to roughly 36" in height so that it and the elevator mechanism can fit under a desk height table. The table supports the drill station.

    The operator has a set of push buttons for a fast elevator up and down to make part loading easier. Once the cassette is loaded the elevator will switch over to a index operation.

    The cassette needs to have a part alignment feature. This could be two temporary bars that are dropped down from the top of the cassette into the part u-shaped slots. Once all 30 parts are aligned the bars are carefully pulled out. Or it could be two fixtures that sit on the table top and slide against the cassette sides. The fixtures have projections that fit into the shelf that align the parts.

    Or it is some very clever feature added to the cassette shelf plate that does the alignment without interfering with the part push out/ push in operation of the cassette. The feature might be a set of spring loaded hinged alignment blocks that swing out and release the part when the pusher bar is in operation. Plan on using two more pneumatic pistons to perform this operation.

    All makes perfect sense to me, I'll get this drawn in cad today.

  2. #82
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    Regardless how you load the drill fixture, you will need some way to insure proper orientation. With a cassette there is no guarantee that the part will be hand loaded correctly without some kind of preload sensor. As stated, what you have now is bullet proof.

    The other option to having orientation sensors is to move the top drilling to the drilling station. More cost of course, but time will be saved in the cnc.

    Your overall goal as I see it is to minimize cnc time. If the overall time to drill the four holes is significantly smaller than the cycle time of the cnc then possibly adding the additional drilling time would reduce the overall cycle time and prevent quality problems. If a human is required to guarantee quality, THERE WILL BE FAILURES.

    Another benefit to the cassette is loaded cassettes could be stored until parts are needed or time permits.

    Tom

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    Quote Originally Posted by as9100d View Post
    I'm all ears. As long as it doesn't involve using an existing CNC mill that costs $100,000
    Like you said, I don't know your capabilities...but you do. Perhaps you have exhausted all other options, or maybe it's just being overlooked.

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    Quote Originally Posted by TDegenhart View Post
    Regardless how you load the drill fixture, you will need some way to insure proper orientation. With a cassette there is no guarantee that the part will be hand loaded correctly without some kind of preload sensor. As stated, what you have now is bullet proof.

    The other option to having orientation sensors is to move the top drilling to the drilling station. More cost of course, but time will be saved in the cnc.

    Your overall goal as I see it is to minimize cnc time. If the overall time to drill the four holes is significantly smaller than the cycle time of the cnc then possibly adding the additional drilling time would reduce the overall cycle time and prevent quality problems. If a human is required to guarantee quality, THERE WILL BE FAILURES.

    Another benefit to the cassette is loaded cassettes could be stored until parts are needed or time permits.

    Tom

    I think the loading position will be less of an issue than loading in the mill because of the hand manipulation aspect and the way the brain works. Loading the cassette with the dot facing the employee and visually checking should reduce errors to an acceptable level.

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    Quote Originally Posted by as9100d View Post
    I think the loading position will be less of an issue than loading in the mill because of the hand manipulation aspect and the way the brain works. Loading the cassette with the dot facing the employee and visually checking should reduce errors to an acceptable level.
    What is acceptable from your customer's standpoint?

    My training has been in six sigma.

    Tom

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    Quote Originally Posted by TDegenhart View Post
    What is acceptable from your customer's standpoint?

    My training has been in six sigma.

    Tom
    We are ISO and as9100d and follow a zero defect culture. All parts get 100% inspected

    We have a fixture with sliding gage pins we use to check these parts for the outside holes and location.

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    Quote Originally Posted by as9100d View Post
    Igus isn't cheap crap, ive used their bearings for all sorts of stuff and they work great.
    Well, you asked for opinions. I gave mine. Plastic creeps over time, end of story. I suppose you could make them work, but I don't see the point. Maybe if you have lots of length and want to save a few bucks and the application is not critical. Some guy on here was going to make a 5 axis machine using plastic ways. I wonder if that will ever turn out.

    I like the 2 or 4 spindles for the coaxial constraint. You could also have one drill then another spindle that reams through both.

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    stack 50 parts in a vertical magazine, index fingers retain bottom part in stack, positive feed downward tp drilling position, 4 drills advancing through drill bushings, after drilling, the part moves downward and is ejected. drill bushing also helps strip curls off the bit. even hand feeding these would be fast. maybe just as fast as loading a magazine and restacking them when done.

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    Quote Originally Posted by CosmosK View Post
    Well, you asked for opinions. I gave mine. Plastic creeps over time, end of story. I suppose you could make them work, but I don't see the point. Maybe if you have lots of length and want to save a few bucks and the application is not critical. Some guy on here was going to make a 5 axis machine using plastic ways. I wonder if that will ever turn out.

    I like the 2 or 4 spindles for the coaxial constraint. You could also have one drill then another spindle that reams through both.
    All options are welcomed and thanked. The plastic linear stuff has come a very long way over the years. I'd only use it for moving the cassette up and down only. Not much force there.

    A 5 axis or any axis mill wouldn't do well. Too much slop! And not rigid at all.

    I've got some metal square profile linear guides picked out for the drill movement.probably use small ballscrews and servo motors to drive them.

    My though is to have 2 drill spindles, skip the specialized bits we use now and have one spindle per drill size using carbide drills.

    More rotations but that's ok.

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    If you don't mold it then I would set it up on the 4th axis in a multi-station vise so I could hold more parts and finish them in 2 ops. The vise shown would hold 16 parts but I think 8 would be the size you would want for a 20" travel machine. It takes me 20 seconds, on average, of spindle downtime to swap 4th axis fixtures with repeatability in the tenths. The time savings of loading and more parts per cycle should counter the time lost to finishing the parts on the VMC. Sure it means making some custom vises but it would be a hell of a lot less work to make than a custom machine and a lot more versatile.




    vise.jpg

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    It looks like you are doing them one at a time on the 4th? I'd figure out how to get 2 parts on on the 4th you have.

    Then if you still wanted too, build two air/oil carriages with drill motors straddling your existing 4th, one mounted in front of the 4th and one behind, run the drills off an m-code. You would drill one hole in each part then index 90°. This would be happening in parallel with the main spindle doing the first two ops. All the chips and coolant stay in the mill.

    Or run in on a twin turret lathe with a sub spindle and be done in one...

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    Quote Originally Posted by CosmosK View Post
    Well, you asked for opinions. I gave mine. Plastic creeps over time, end of story. I suppose you could make them work, but I don't see the point. Maybe if you have lots of length and want to save a few bucks and the application is not critical. Some guy on here was going to make a 5 axis machine using plastic ways. I wonder if that will ever turn out.
    Studer manufactures cylindrical grinders with a plastic way layer that is capable of holding dimension errors to less than .00004" over a 25 inch part length. (That .00004" is not a typing error.) Spend a few minutes reading about their machine specifications and design on their website.
    Then report back to the forum and let us know if your opinion about plastic bearings has changed.

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    Quote Originally Posted by DavidScott View Post
    If you don't mold it then I would set it up on the 4th axis in a multi-station vise so I could hold more parts and finish them in 2 ops. The vise shown would hold 16 parts but I think 8 would be the size you would want for a 20" travel machine. It takes me 20 seconds, on average, of spindle downtime to swap 4th axis fixtures with repeatability in the tenths. The time savings of loading and more parts per cycle should counter the time lost to finishing the parts on the VMC. Sure it means making some custom vises but it would be a hell of a lot less work to make than a custom machine and a lot more versatile.




    vise.jpg
    I just don't want to tie up expensive CNC machines with simple drill features.

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    Quote Originally Posted by as9100d View Post
    I just don't want to tie up expensive CNC machines with simple drill features.
    You won't. The time savings of increased efficiency should cover the extra time to drill the parts, the loading time savings alone should more than cover the time to drill the holes. PLUS there is ZERO extra labor since it is ONLY 2 ops this way, unless I am not seeing something in the part. Plus your $15-$20k Robodrills should be cheap to run.

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    That vise setup would easily cost more than the $5000 ive got planned for this machine. Plus there is something that most dont think about and thats rotating that fixture around just to unload/load. Horizontal tombstones are neat and they do work well for long cycle time parts but when you are talking 2.5-3 min per part, You switch out too frequent to see the savings.

    Nmbmxer has the best solution, which I already know but cant afford.... twin spindle lathe with live tools for a one and done but I dont have $150,000 laying around anymore.

    Also a Horizontal mill would work well, We have one on our wishlist but havent made the purchase yet. Maybe 2nd quarter of next year ill buy one.

    Ill also mention that these are ran on a haas dm2 right now and Id like to free this machine up completely and move all of this to a robodrill with a pallet changer. 4th axis isnt on that machine so an off machine solution is needed.

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    I never swap parts while the spindle is stopped, only fixtures. 20 seconds per fixture/ 8 parts swap, hard to beat that. No 4th so that kills this idea.

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    Why not go back to basics. Put a human on the load station.

    Tom

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    Swapping a fixture would be ok if 4th was there.

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    I spoke with a machine camera vision company today about using a camera to detect orientation. They can do it while the part is moving and I've got just the spot to put it.

    I'm waiting on a quote now.

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    Quote Originally Posted by as9100d View Post
    I spoke with a machine camera vision company today about using a camera to detect orientation. They can do it while the part is moving and I've got just the spot to put it.

    I'm waiting on a quote now.
    If you plan on using the camera for quality control as well you will need to equip the camera with a telecentric lens. These lenses have very low image distortion It prevents the circular holes appearing as oval shaped holes when viewing features at the edge of the picture frame..
    Edmund Optics is one source. There are many others.


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