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    Quote Originally Posted by dertsap View Post
    sandvik has a great software calculators for this ,the sfm is far different using their calculator than what you see on the back of the insert box , it takes into account the material , insert grade , depth of cut engagement , tool dia , # teeth , and calculates it to cubic inches per minute removal , which makes more sense , and the speeds are unreal
    Funny you mentioned this. With my Sandvik 390, the online calculator said 1300 SFM for cutting 1018/1020 steel. I had a real hard time believing the recommendations. I expected to trash $100 worth of inserts on the initial engagement, but it ran great.



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    After being away from this thread for some time I've come to a conclusion. One of our original topics was "what is the single most important factor in HSM". I realize everything we've talked about is a factor. High Pressure coolant, tool dynamic's, fixturing, control, etc... but, I feel Scott_Bob is right. The single most contributing factor in HSM is the control. Without it, the rest can never acheive their optimal performance levels regardless of all the other things we've talked about. The other things discussed can help a bad machine / cutter work better but, you can only optimize the cutting condition based on the capabilities of the existing control. If your control can't handle HSM machining, nothing else you do will make it work.

    Gunner

    Gunner


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    I see that this thread is pretty old but I'll give it try anyway. Camminc, Although I hav'nt read this thread verbatum, I've noticed that it seems to deal mainly with the tool/holder assy. Would this and or how would this "Dynamic Characterization" deal with a work piece that is not "idealy", (for lack of a better word) mounted to the machine tool? Work pieces vary greatly, as you know, I'm sure.



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    Quote Originally Posted by camminc View Post
    To Lerman:
    The "Stackup" consists of the tool, holder, gage length, number of teeth, tool description, picture if wanted, stick out, cutter material, etc. This "Stackup" is put into the spindle of a machine and an impact test is performed.
    and this determines high speed machining speeds and feeds ? your kidding me !!



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    Quote Originally Posted by fpworks View Post
    Funny you mentioned this. With my Sandvik 390, the online calculator said 1300 SFM for cutting 1018/1020 steel. I had a real hard time believing the recommendations. I expected to trash $100 worth of inserts on the initial engagement, but it ran great.
    do they still have that online calculator i havent been able to track it down , ive got the software but i wanted show a friend online



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    Quote Originally Posted by dertsap
    and this determines high speed machining speeds and feeds ? your kidding me !!
    Yes! Actually, it tells you which feeds/speeds to avoid. It is only applicable when you get over ~8000 rpm. By using the said impact test, you can see which frequencies your machine spindle/toolholder/tool "stack" naturally resonates. Compare this frequency to your flute/second engagements and avoid these speeds/feeds. Using this technique, you can cut tremendously deeper and get better finishes.


    Quote Originally Posted by dertsap
    do they still have that online calculator i havent been able to track it down , ive got the software but i wanted show a friend online

    http://coroguide.coromant.sandvik.co...asp?LangID=ENG

    Click "CuttingDataModule" on the left to start it. They moved their website around quite a bit...I could only find it because it was in my favorites.

    Justin



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    perfect , thank you !
    saved that link



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    Hello ajl6549.

    You ask a very good question. The work piece does have alot to do with the cut and I am learning how to deal with that aspect. I do not have the answer but certainly know it does affect the cut of the cutter at the tool tip. The flexibility of the part and vibration / frequency of it does affect the cut. I guess what I am trying to emphasis is that programming does not control the cut, it is a combination of all dynamic aspects. Cutter, holder, holder fixture, insert, spindle, part, coolant, programming, etc. All I am saying is that it all shows up at the "Tool Tip", and many things can be measured at the tool tip with instruments to help overcome these things. Impact testing can also show flexibility readings of the part, frequency, etc., which have affect on the cutter. There is a calculation of frequency and stiffness of part and cutter to use in machining. If a part vibrates in a multiplier of the natural frequency of the cutter doing the cut, it will certainly have an effect on the cutter if the cutter is of low dynamic or static stiffness, usually static stiffness, dynamic stiffness is used to overcome vibration / chatter frequency of a tool built into the holder, but mostly of a long stick out of over 4x diameter in a lathe operation. Of course there are known variables such as specific power of material (How much power it takes to cut causing more deflection of the cutter), max SFM of material, static and dynamic stiffness of the holder and cutter at a particular stick out, along with spindle and or structural deflection of a force of cut, etc. that need to be looked at when a problem occurs. The idea that programming will overcome all this is ridiculous. It will only be a temporary fix. Programmers for some reason believe they control a machining operation, when in fact they are only a part of the dynamic process and they need to get over it.

    It is a fact that most problems in the shop are looked at as coming from programming and everyone looks at programming to make things work, when in fact the tooling being used may be the culprit. Programmers do not look at the cutter dynamics, they only look at how to go around it to make it work. Tool control looks at the dynamics and then watches to see how programming works with it and then collects the data for them all to use.

    It is pretty simple actually, but a most overlook the process. You start with the stiffest cutter set up, cutter, holder and run it. This is the baseline, maximized process, it is the dynamic platform of the operation, like the foundation of a house. Program the operation conventional and see how it runs. Most likely it will run fine. Some machine tools like to be dampened, so a milling chuck might work better for milling.

    For instance: If your doing a lathe threading operation internally on a 5” housing and you use a 2” diameter bar in a 2-1/2 “ holder on the machine and use a sleeve to mate the tool with a bunch of set screws holding the tool in the holder and the tool is only being clamped in the holder 3” when the machine holder is capable of holding 5”, then the cutter is probably going to cause a problem, instability. Programming can make it work some times, but it will only make things work for a time and then the dynamics of the process will overcome it causing intermediate problems making it difficult to overcome with other parts. Part dynamics do make a difference. The ideas is to use a 2-1/2 inch bar in a 2-1/2 holder, putting it in the holder at the 5” length of holding. Start from the beginning, then work your way out. Etc,Etc.



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    Seems like ultimately your looking at a calculation of deflection and also RPM in order to counter chatter at every level. Wouldn't you need software in order to do this, basically to analyze the workpiece response characteristics throughout the machining process?



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    even in the best of setups with the best of tooling a guy can face harmonics ,and it has to be tweaked out , you can work above it or below it ,in my honest opinion i am a firm beleaver that theory is only theory till it is pushed to the true test , i'm one to follow manufactures specs in reguards to tooling , but , when i want to make chips truely fly my best way of testing for optimal settings is an educated guess and the rest is by ear and i generally know at which point that i have reached the maximum potential and life expectancy of that tool , because it sounds sweet

    A poet knows no boundary yet he is bound to the boundaries of ones own mind !! ........


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    Default Dynamics

    justCNCit:

    You are certainly correct, there are calculations of deflection of specific materials at specific diameters but I do not think anyone can calculate rpm in their mind to counter act chatter unless a chatter frequency is known. You can select an rpm to counter act a chatter frequency if the machine, sfm will allow it.

    Problem being that chatter of a cutter in a cut is occurring at the natural frequency of that cutter or close to it and the human mind, eye and ear can not determine that frequency to tell them the dominate frequency that the chatter is occurring. Therefore, yes, instruments are then required to show us exactly what frequency the chatter is occurring at.

    But, our minds being so intelligent, it stands to reason the we can relate that chatter is occurring by seeing it on the part and hearing it in real time, we just can not say what frequency or amplitude it is producing to counter act it. It could be the part is starting the chatter of the cutter or that the programming of the cutter is causing it to chatter, or that the bar or holder is causing it to chatter, it all has to do with the deflection of the cutter at it's tool tip against forces, either radially, axially or rpm frequency of part osicilation.

    In a nut shell, other dynamic characteristics can be looked at. The siffness of say a bar, a 2-1/2 bar is 62 percent more stable in deflection than a 2" at any given length, in a lathe operation. The bar holder, set screw vs cylindrical clamping, cylindrical clamping is better. The bar might only be in the holder 3 inches when it can be held in the holder 5 inches? ETc, Etc.



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    i can see testing as a base to start on but now a few of the things that i'm not quite understanding about this testing are the the following :

    does the xyzabc get impact tested
    how does spindle rpm affect the natural frequency , belts , gearboxes
    how does the use of high pressure thru spindle coolant affect the tool frequency
    when impact testing the part is this done thru every stage of the process especially corners
    many times i will slightly dull a sharp new cutter to remove chatter if it is happening ,how does this affect the cutting frequency
    how does vise or fixture clamps torque affect the frequency of the part
    if i change a tool or its length .1 what affect will this have ,do i have to retest
    depth of cut or engagement
    unbalanced or flute runout
    does the machine temperature affect the frequency
    how does a large hogging machine running beside the machine in question affect it
    at how many points would say a 24"H x 12x12W tombstone be tested
    how does the load on the spindle affect the frequency

    don t get me wrong here by me asking these questions but i truely beleave that there are a number of issues that revolve around tool chatter , i can buy into the idea of impact testing a tool to test how rigid it is and documenting it for future reference but i find it difficult to beleave an impact test will determine if i will have chatter on my part or not

    A poet knows no boundary yet he is bound to the boundaries of ones own mind !! ........


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    I really can't explain it anymore on how it works, the people on this forum just don't seem to get it or just don't want to get it. I have preached it over and over again. If you really want to know you will have to contact me. It's not that difficult, it only seems that way. Randy



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    wow! lots of interesting info. really enjoyed the amount of knowledge and experience. remember you are debating with a salesman. dont get upset if he doesnt agree his product (paycheck generating) isnt the solve all.
    camminc, your product is definitly a great tool in achieving perfect machining conditions but you might want to take a course in sales to learn to promote your product in a more pleasant manner.
    just my .02



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    Quote Originally Posted by minner slinner View Post
    learn to promote your product in a more pleasant manner.
    just my .02
    he's fine , he's just defending what he does , nothing wrong with a respectfull debate or frustration

    but my questions were of genuine curiousity as to how those factors do indeed affect the frequency

    A poet knows no boundary yet he is bound to the boundaries of ones own mind !! ........


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    Mostly a bump for this thread as I got sick and tired of seeing the "what the hell can I do" thread every time I scrolled down the site

    On a positive note I am looking seriously at a Nakamura WT 100 for some "Hard" Milling. With Hard being relative for sure. Mostly 4140 @45 Rockwell. But when you do almost all alum that is hard
    Almost double the money but the new CUBLEX-25 looks like a great machine. Cant wait for IMTS
    Gary



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    im seach coroguide.but i can't dowload it.please !you sent file coroguide to bkpro37.thanks alot.i need you



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    This website explains impact testing and stability lobe diagrams
    http://highspeedmachining.mae.ufl.edu/htmlsite/faq.html



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    Default Impact and High speed

    Little Story:

    I am not upset with anybody and I certainly don't make a living selling this stuff, I have never sold any impact testing equipment ever, I only refer people to it and to the people who do it, if asked. I do it because I believe in it and respect those who have taught me and that do this stuff. They are the ones that have the knowledge and do the amazing things. Of course I will sell anyone software though to keep track of tooling being impacted and have sold about 50 units in the past 10 years to companies needing it, but it is software written to compliment impacting data, specific to impacting only. I am providing a solution if a company wants it. I don't sell any impact software anymore since the software is beyond my capabilities anylonger. Tooling companies are recognizing the need for impact software and are now developing their own for their products, cutting me out of the loop. I just happened to come up with the idea before them in the early years but was never interested in making a living in it. They provide what is called "Dashboards" for stable rpm's and internet connected software data now, something I am not capable of doing.

    Actually I work a regular job like everyone else, not doing this stuff. I am a regular guy that just happened to have the opportunity to learn about dynamics and it has made my life a lot easier. I just know this stuff and want to share it, but I always run into people that want to be skeptical and make a big deal out of things, when they don't even know anything about it. I don’t want to be a salesman, I don’t care about sales, I just tell it like it is and have no one to answer to but myself. The same as I refer people to shrink fit or balancing, they are good things to have and know also.

    Right now I work for a large company that makes millions of dollars and they can't stop and listen for one moment on how Impact testing would help them and save them thousands of dollars. I have worked for them for 8 years now and they still don't understand that I am trying to help them when it comes to advanced dynamics, as I am trying to on this forum. Actually, they resent it when I try and talk to them about it or help them, don’t understand why. I can only guess that at my work they think they know it all and refuse to believe that it won't help them. People in positions that should know this stuff don’t and I guess it makes them look bad or something, when instead they should embrace the concept. Example: They have a new multimillion dollar machine coming in soon and can't see the advantages of impacting for it, as I can see. You can do all kinds of wonderful, money saving things by impacting this new machine. Do a vibration signature for evaluation and repair of spindles, motors, tooling, etc. Frequency modal analysis for all kind of things from chatter to maintance. It even works as a backup tool to show the machine manufacture that the machine is or isn't up to spec on it's dynamic structure readings from the factory, it can show that the manufacture of the machine is wrong or right in the assembly of the machine for warranty purposes, etc, etc.

    Truth is at where I work, dynamics has already helped them and they don't want to admit it or want to understand it. Example: I run a CNC lathe, they put a dampened bar on it for threading believing it was infallible and the total best thing to use.

    Well, it was actually the worst thing they could have done and they were heck bent on not listening to me as to why, even though I was 100% correct. The bar had to be cut and modified to fit on the machine totally destroying it's dynamics and dampening characteristics, etc, etc. It chattered all the time and was causing unstable conditions, creating nothing but trouble for us operators. I know, I was running it. I told them and told them over and over and over again what the problem was. It took them two years to switch over to what I told them, because of the politics, never admitting they were wrong, etc, etc.

    I had to make a big stink about it, even got the manufacture of the bars in to the shop to talk to them. The manufacture is a well know tooling manufacture that sells tools all over the world, yet they didn't even know it was the wrong bar for the application until I explained it to them. The guy selling the bars had no idea how and what was required of the dampened bars. I understand this because I have worked with many tooling sales people. They don’t understand this type of technical stuff because they have no training in it. Well, they ended up firing the sales guy, because eventually they knew they would loose all kinds of business due to this, etc, etc. And they did, from us anyway. The company I work for never said thanks, never shook my hand, not a word about it. No one had the guts or respect to admit, reward , recognize and go on. They spent $6000 on 4 bars for two machines, scrapped many parts causing hundreds of thousands of dollars in rework, etc, etc. And finally replaced the bars to the ones I wanted in the first place and the problems went away. Of course I never got any recognition, but I am sure someone did?

    The only reason I knew that he bars were not correct was because I have done Impact testing and been trained in dynamics and understood these things. There are many other processes in manufacturing that could benefit from Impacting and dynamics but people simply won't change antiquated ways, etc, etc. They always have a reason not to understand or trust it and it is ashamed. Because of this, our industry is behind and only hurting themselves. I see it happen every day at the place I work.



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    Hi camminc,

    thank you for your sharing. I believe that you are correct because I ever see the effect of dynamic analysis to improve surface quality even I never do it by myself.
    I think this is an misunderstanding in this thread. The initial question is about HSM. HSM is a complex system. This include machine, CAD/CAM software, tooling system and programmer. Your point if view is only in tooling system area. Other people point of view specially is machine area. I haven't see people talk about CAD/CAM software and programmer capability in this thread.
    Base on my experience in HSM, we must know the machine characteristic first. Must understand about spindle power, controller capability, data storage capability, data transfer, servo response, PLC response, etc.
    After that we can select suitable tool and cutting method. The key point is programmer, because he is the person who will combine all those factor.
    I always said to my colleague that HSM method is similar with F1 racing for easy understanding. We can see analogy between machine and F1 car, tooling system and F1 tyres, programmed toolpath and race circuit, programmer and F1 driver.
    F1 team must aware about all factor and F1 driver must have ability to combine all those factor. You can imagine if the team have good tyres but their car is unstable, are they can win the race?
    Or, they have good car, tyres but the driver don't understand the circuit, I think they will fail also.
    The winner is a team that have good car, good tyres, understand the circuit very well and have driver who can drive it very well.
    This is similar with HSM. The people who can combine all those things can get big advantages of HSM.
    I have experience when making one mould. This is one year machine (installed at May 2008) with latest and highest controller of FANUC. By using same machine, I try to change cutting method, tool, cooling method and change some machine parameter related acceleration and deceleration, and I can improve machine productivity 100%.
    Once more, HSM is complex system, we can't see from one point of view. Everybody who write in this thread is correct but they are see from different point of view.

    This is just my opinion. Sorry for my bad english.



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What is high speed machining

What is high speed machining