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  • Need Face Milling Advice

    I have inbound from an Ebay supplier, a face mill that takes 5 TPG 432 inserts. I have turned semi-pro*, but I have little experience with face milling. My neighbor makes molds for the plastics industry, and I prep the metal blocks he gets from his supplier.

    Diameter 5"
    Inserts: TPG 432 - five of them
    Steel to be cut: S7 tool steel, 4" wide, annealed.
    Mill: Bridgeport J knee mill. 1 HP.

    What RPM, what feed rate, and what depth of cut are advisable?

    The assignment is to reduce the thickness of this block from approx. 2.045" to 1.900" -0.000 +0.010". Can this be done in one pass?



    * semi-pro. I get paid for my work, but it is not my primary source of income.

  • #2
    What SFM do your inserts suggest? SFM is coating dependent. Are they set positive rake? If you don't know insert details, start at 400 sfm (about 300 rpm) and adjust your feed and DOC for nice blue chips. You need a minimum chip load per insert for effective cutting and you might not get it...

    Why?

    5 inch is pretty aggressive on a 1hp BP for steel (or most other materials). Take it easy... you don't have to load all inserts - at that diameter and HP I'd start with three so you can keep your chip load up. With one it's basically a fly cutter.

    Can you do it in one pass? depends... I wouldn't with those inserts and diameter. Start at 30 thou and see how it performs.
    Last edited by lakeside53; 03-26-2017, 09:56 PM.

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    • #3
      TPG inserts do not make a very good face mill. You would be much better off with a 45 degree SEKR square insert. With either one, it's not likely you can take off .145 thou in one pass with one HP. Even if you could, the surface finish would not be good enough for mold blocks. You will need a .002 to .005 finish pass no matter what, depending on how rough the roughing pass leaves the surface. Thankfully, S7 is easier to cut than a lot of tool steels. Your mill is a bit light for this job, but will do fine with 2 or 3 roughing and one finish pass. I would start with 3 .045 depth of cut passes. then 1 .010 finish pass. Maybe 500 RPM, .003 per tooth feedrate. You will have to see how the mill does with that and adjust up or down accordingly. Perfect tram and tight spindle bearings will factor into the equation.
      Kansas City area

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      • #4
        SEKT at 45 is what I use. Love them. But rarely do I go above 2.5 inches on a BP.

        Comment


        • #5
          Originally posted by Toolguy View Post
          TPG inserts do not make a very good face mill. You would be much better off with a 45 degree SEKR square insert. With either one, it's not likely you can take off .145 thou in one pass with one HP. Even if you could, the surface finish would not be good enough for mold blocks. You will need a .002 to .005 finish pass no matter what, depending on how rough the roughing pass leaves the surface. Thankfully, S7 is easier to cut than a lot of tool steels. Your mill is a bit light for this job, but will do fine with 2 or 3 roughing and one finish pass. I would start with 3 .045 depth of cut passes. then 1 .010 finish pass. Maybe 500 RPM, .003 per tooth feedrate. You will have to see how the mill does with that and adjust up or down accordingly. Perfect tram and tight spindle bearings will factor into the equation.
          Problem is, the part arrives Friday. I have a 3" that uses TSA brazed carbide. Not real good. SEKR face mills are very PRICEY. The inserts, too. If I were a full pro shop with a backlog, and half dozen employees, then that kind of mill would probably be standard. I paid $140 for this mill.

          Using less than 4"+ means multiple cuts for each depth. Trying to reduce time.

          I'll try a single pass .025" and the same feed I've been using. I'll go the 300 pm, and look for purple chips.

          Comment


          • #6
            Be careful with your tram. Your surface may look "smooth" because you are cutting 5 inches wide, but it's very easy to dish the wide surface. Watch the trailing edge of the face mill; if you are cutting with that or scuffing with the front when you step over.. your tram is out, or, the pressure from the wide fm is simply showing you how lose your spindle/quill really is

            Do you really save time with excessive width if you have to cut shallower? Same with inserts... there a reason SEKx cut better, and you have 4 corners. I watch cost also, but I scrounge mine on ebay and get quality insert for roughly $5 each. You just need to watch carefully and deal with bad (can work for you) descriptions.
            Last edited by lakeside53; 03-26-2017, 10:54 PM.

            Comment


            • #7
              Originally posted by John Buffum View Post
              SEKR face mills are very PRICEY. The inserts, too. If I were a full pro shop with a backlog, and
              half dozen employees, then that kind of mill would probably be standard...
              Yeah, if you want to play with the big boys you have to have big boy tools. A 5" mill with TPG inserts on a 1HP Bridgeport will
              not make you happy and it will not make you money. You will fight and struggle with it the entire time you use it. The lower
              the HP and the lighter your machine the more you need really positive rake tooling. Yes the SEK and APK tools and inserts are
              expensive but they work much better on small machines--you won't believe the difference till you try them.

              How much material do you need to remove? If there's much, especially if there is some depth involved, the fastest way to
              remove material with a small, light mill is to use roughing cutters. Turn them slow, bury them in the cut and turn the feed up
              till they're happily chomping away. Finish up with your big facemill. Another thought is to use a 1-1/2"-2" facemill and finish
              up with a flycutter...
              Keith
              __________________________
              Just one project too many--that's what finally got him...

              Comment


              • #8
                Face milling need not be overly expensive. Here are a few quick examples to illustrate... Make sure to match the arbor size to the face mill size, and inserts to face mill pocket. Do not buy an aluminum body face mill. It won't last very long.

                http://www.ebay.com/itm/261248200534...%3AMEBIDX%3AIT

                http://www.ebay.com/itm/302237169373...%3AMEBIDX%3AIT

                http://www.ebay.com/itm/361866224739...%3AMEBIDX%3AIT

                http://www.ebay.com/itm/282378771256...%3AMEBIDX%3AIT

                http://www.ebay.com/itm/222401606978...%3AMEBIDX%3AIT

                http://www.ebay.com/itm/272586229481...%3AMEBIDX%3AIT

                http://www.ebay.com/itm/371788995652...%3AMEBIDX%3AIT
                Kansas City area

                Comment


                • #9
                  Originally posted by Toolguy View Post
                  Face milling need not be overly expensive. Here are a few quick examples to illustrate... Make sure to match the arbor size to the face mill size, and inserts to face mill pocket. Do not buy an aluminum body face mill. It won't last very long.

                  Does anyone know what's the "deal" with aluminium body insert mills?
                  Saw some of those earlier and was wondering if it is a chinese ebay sellers invention to save on postal fees or is there some other benefit that I dont see?
                  Machining the body would be cheaper but other than that.
                  Location: Helsinki, Finland, Europe

                  Comment


                  • #10
                    Originally posted by LKeithR View Post
                    Yeah, if you want to play with the big boys you have to have big boy tools. A 5" mill with TPG inserts on a 1HP Bridgeport will
                    not make you happy and it will not make you money. You will fight and struggle with it the entire time you use it.
                    I personally believe that TPG's should be outlawed.. They have caused me nothing but frustration... SLAM SLAM SLAM SLAM SLAM SLAM...
                    Then you have to hope you can find a good insert for milling (or as good as a TPG can get).. Bonus if its not a super cheap holder and
                    the inserts are laid back a few degrees to give you a tiny bit of positive cutting action, quiets the SLAM SLAM SLAM SLAM SLAM down
                    a little bit...

                    I threw out and sold off every TPG bit of tooling I had years ago, I realized it sucked and I was never going to use it again, and I didn't
                    want to be tempted to use it again..


                    The way I see it (and I don't think I'm alone).. You are already behind the 8 ball with a floppy noodle of a machine and almost no
                    HP.. Now you are going to throw an oversize cutter on it with the worlds worst geometry... You are going to hate your life.

                    An SExx facemill will pay for itself fairly quickly.. Inserts are usually less than $8.. They lay WAY back and have some really nice
                    free cutting geometry. The 45 thins the chip, so you can feed the B'jesus out of them (low DOC), and what would be most important
                    on a smaller machine, the lead angle pushes a lot of your cutting force straight back up through the spindle, effectively making
                    your machine more rigid than it really is.

                    Comment


                    • #11
                      Here you go, a 50mm 4 insert SEKT milling holder for US$34 in your mail box, or the 100mm 6 insert version for US$71.

                      https://www.aliexpress.com/store/pro...612.0.0.miVHLr
                      https://www.aliexpress.com/store/pro...612.0.0.knE63Z

                      Add a packet of 10 inserts for US$43

                      https://www.aliexpress.com/store/pro...612.0.0.7cbqS6

                      No affiliation, just a happy customer. Downside is slow delivery, can be be up to 3 weeks, plus the website is not the easiest to follow.


                      Originally posted by John Buffum View Post
                      SEKR face mills are very PRICEY. The inserts, too. If I were a full pro shop with a backlog, and half dozen employees, then that kind of mill would probably be standard. I paid $140 for this mill.
                      Last edited by bob ward; 03-27-2017, 07:50 AM.

                      Comment


                      • #12
                        IMHO, this is the type of recurring job that might justify have a 12" or larger shaper in the shop.

                        Comment


                        • #13
                          Originally posted by bobw53 View Post
                          I personally believe that TPG's should be outlawed.. They have caused me nothing but frustration... SLAM SLAM SLAM SLAM SLAM SLAM...
                          Then you have to hope you can find a good insert for milling (or as good as a TPG can get).. Bonus if its not a super cheap holder and
                          the inserts are laid back a few degrees to give you a tiny bit of positive cutting action, quiets the SLAM SLAM SLAM SLAM SLAM down
                          a little bit...

                          I threw out and sold off every TPG bit of tooling I had years ago, I realized it sucked and I was never going to use it again, and I didn't
                          want to be tempted to use it again..


                          The way I see it (and I don't think I'm alone).. You are already behind the 8 ball with a floppy noodle of a machine and almost no
                          HP.. Now you are going to throw an oversize cutter on it with the worlds worst geometry... You are going to hate your life.

                          An SExx facemill will pay for itself fairly quickly.. Inserts are usually less than $8.. They lay WAY back and have some really nice
                          free cutting geometry. The 45 thins the chip, so you can feed the B'jesus out of them (low DOC), and what would be most important
                          on a smaller machine, the lead angle pushes a lot of your cutting force straight back up through the spindle, effectively making
                          your machine more rigid than it really is.
                          OK. I'll save this info away, and see how the TPG cutter does. If, indeed, it is not good, then $225 for a 5" SE42 6 tooth mill might not be a bad idea. It all depends on how much work my neighbor gives me. The TPG cutter is $140. SEKN inserts are $6 apiece. Not bad. Hmmm. 6 x $6 = $36 on the mill. The nice thing about its the 1.5" R8 arbor works on both. $40 saved.

                          Oh yes. One respondent was concerned about accuracy. I'm just doing the rough dimensioning. The precision stuff is done on a precision grinder, then, it is stoned. The mold patterns are then burned in by EDM. I'm in conversations with him to learn on the grinder. His sons are doing the pins and channels. He does the AutoCAD and the carbon EDM patterns.

                          If the work continues, and I keep the customer happy, then a SE42 head may be on down the road, maybe June. If I do buy one, should I go with 4" or 5"?

                          My friendly neighborhood industrial surplus house has a bucket load of TPG 4xx inserts. $3 each. I'll check if they have SE inserts.

                          Comment


                          • #14
                            Originally posted by bob ward View Post
                            Here you go, a 50mm 4 insert SEKT milling holder for US$34 in your mail box, or the 100mm 6 insert version for US$71.

                            https://www.aliexpress.com/store/pro...612.0.0.miVHLr
                            https://www.aliexpress.com/store/pro...612.0.0.knE63Z

                            Add a packet of 10 inserts for US$43

                            https://www.aliexpress.com/store/pro...612.0.0.7cbqS6

                            No affiliation, just a happy customer. Downside is slow delivery, can be be up to 3 weeks, plus the website is not the easiest to follow.
                            A close reading of the ad "Material: alloy". These are aluminum heads. Anyone out there tried aluminum heads?

                            Comment


                            • #15
                              Alloy could mean alloy steel or aluminum alloy.
                              Location: Helsinki, Finland, Europe

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