New Machine Build Hold aluminum without marking surface


Results 1 to 5 of 5

Thread: Hold aluminum without marking surface

  1. #1
    Registered ghyman's Avatar
    Join Date
    Feb 2005
    Location
    USA
    Posts
    303
    Downloads
    0
    Uploads
    0

    Default Hold aluminum without marking surface

    Our sales department sold a promise that I have been tasked with fulfilling, but I do not have a good idea how to proceed... Hopefully there are some workholding experts here who know an answer...

    The machine is an Okuma Horizontal Mill (MB8000H)

    The part is 6061-T6 Aluminum.

    Finished part is ~200 Lbs, rough block is roughly 30"x40"x8" (1300 lbs)

    op 10 is to mill out a 9" through bore, a 23.5" counterbore 6.5" deep, and about 75-80 holes on the front and back of the part. The fixture is pretty straightforward; serrated clamps on 3 sides and a pair of locators on the 4th, with a large opening to give access from the back.

    op 20 is the problem... The part will be laid down on the table and machined to a roughly hexagonal shape (op 10 is clamping on/near the corners of the block that are machined away to get the hex shape), each face having a large obround slot that goes through the face into the bore from op 10. And about 20-30 additional holes on each face.

    The original intent was to clamp through the 9" through bore from op 10 and clocking the part with a few pins in two of the larger holes on the back side of the part. However, the sales department sold the customer on the idea that the entire part will have a 32rms finish on all faces and will require *zero* hand working to remove and machine marks or clamp marks, and will be completed in two operations. We've had very good luck with a fiber brush we've been testing on a different machine, and are easily getting the required surface finish as well as leaving a uniform-looking surface all over.

    Clamping through the large bore will hold the part well enough to machine it, but the concern is that any kind of clamping on the counterbore will leave marks in the finish from op 10, Op 20 will remove roughly 150-200 lbs lbs of chips, so I fully expect to have to clamp pretty tightly to hold it in place, and I also expect the part to do a little moving.

    I've gotten the job processed and tooled up , but was only made aware of the "zero hand-working" requirement yesterday. I personally do not believe it is doable, but thought I would ask some experts.

    Does anyone have any suggestions on a good way to hold a 200 lb aluminum part in a horizontal without leaving any marks on any surface?

    Similar Threads:


  2. #2
    Community Moderator Jim Dawson's Avatar
    Join Date
    Dec 2013
    Posts
    5717
    Downloads
    0
    Uploads
    0

    Default Re: Hold aluminum without marking surface

    Sounds like a typical case of sales selling something that can't be done.

    Short of building additional fixturing, the only quick way I can think of is to add a 3rd op, and rough bore in op 10, then finish the bore and counterbore with op 30



  3. #3
    Registered ghyman's Avatar
    Join Date
    Feb 2005
    Location
    USA
    Posts
    303
    Downloads
    0
    Uploads
    0

    Default Re: Hold aluminum without marking surface

    Thanks; I've been considering either that or a vacuum fixture for op 20.

    I appreciate the input.



  4. #4
    Member
    Join Date
    Jun 2010
    Location
    Australia
    Posts
    4252
    Downloads
    4
    Uploads
    0

    Default Re: Hold aluminum without marking surface

    the sales department sold the customer on the idea that the entire part will have a 32rms finish on all faces and will require *zero* hand working to remove and machine marks or clamp marks, and will be completed in two operations.

    Ask the Sales Dept for exact instructions on how to do this. You could even invite them to run the machine. If they decline, tell them to get out of the kitchen.

    Just what is one operation anyhow? Replacing a hip joint is one medical operation after all ... Simply redefine what the word means. If Sales objects, see above.

    Try putting some soft aluminium sheeting between the clamps and the finished surfaces. That may absorb the pressure enough that you won't see any marks.

    Cheers
    Roger



  5. #5
    Member
    Join Date
    Jun 2012
    Location
    usa
    Posts
    182
    Downloads
    0
    Uploads
    0

    Default Re: Hold aluminum without marking surface

    Cast a fixture in place using low melt temp metal. Once the machining is done, melt the fixture.

    p.s. You didn't mention cost



Tags for this Thread

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •  


About CNCzone.com

    We are the largest and most active discussion forum for manufacturing industry. The site is 100% free to join and use, so join today!

Follow us on


Our Brands

Hold aluminum without marking surface

Hold aluminum without marking surface