[quote=JCMills;767012]
Originally Posted by camminc  Little Story: I need to find out about impacting and how the discussion started and how do I get to it or search it out. I assume you are talking about the dynamics taking place with the resonance etc from the impacts of the cutter teeth. let me know how to find out about it please. Thanks Jeff |
Jeff: To answer your question about how this thread got started: This is going to be a long one.
This discussion started somewhere around 4-2003 with a couple of long time forum guys named Hardmill and Scott-bob. Hardmill is I guess some kind of programmer and Scott-bob races desert cars and is some kind of CNC process engineer. Neither one of them probably never had any practical experience with actual HS machines, tooling, etc. So, I rebutted their ridiculous beliefs for about 2 years and then moved on. Their ideas and methods were dinasourish, unpractical and certainly inexperienced.
I, Camminc, on the other hand am a real time user of impact testing equipment on the shop floor in a high speed manufacturing environment. I personally do shrink fit with induction heating and balancing of tool assemblies dynamically and static. (Single plane and Two plane). I have been a tool and cutter grinder for over 20 years and taken care of tool cribs, inventory and control, presetting for milling machines, purchase tooling and eventually design and participate in HSM. I have done nothing but tooling all my career, on the shop floor, cutting tools for the past 30 years. I don't talk about knowing programming or race cars because I don't know much about them, but I do know tools.
I joined the SME in 1998, about 25 years into manufacturing, wanting to learn about HSM, shrink, balance and chatter. I went to Westec to hear what Boeing had to say about it all, at a HSM clinic I paid $400 to go to, my own money. The company I was working for was venturing into it and I was the fall guy if anything went wrong, so I do what I do, learn. They did reimburse me when they found out I went on my own. I made good progress as time went by and the balance guru at Hoffmann noticed my enthusiasm and asked if I wanted to speak at some SME HSM Clinics about the advanced methods I was using and learning, since I was going into uncharted territory, he was watching me. At the time he was head chairman of the HSM clinics for the SME.
Well, anyway, I traveled for about a year doing the SME circuit for the company I worked for, meeting Boeing people and many other wonderfully, knowledgeable people from all kinds of companies doing HSM at the time. I went with Harold Cook (Patent Holder Shrinker) to Boeing Everett, Seattle, Portland, Wichita, Ingersoll in Illinois, Kennametal plus a few other well known companies doing HSM at the time. I ended up with a couple of patents being filed by my employer on balancing for HSM tooling, wrote 3 technical articles for Mold Making Technology Magazine while there, 5 now, involved in a SME tour of our plant in CA, met and made friends with Harold Cook, patent holder of the Shrinker, I was trained by Dr. Scott Smith and Dr. Thomas S. Delio of MLI in dynamics, impact testing, dynamic characterization, chatter detection and correction and audio chatter recognition. Dr. Delio developed the Harmonizer. Dr. Delio also headed up CRAC, Chatter Recognition and Control at the controller, Makino, etc. Now things are called Blueswarf, must be Kennametal has taken over allot of it from Dr. Delio. Tom and I still see each other and are good friends.
Anyway, just so you know my back ground, I couldn't take all the bean dip that Hardmill and Scott-bob were dishing out on this forum and decided to set it straight. It really doesn't matter if any of the readers believe what I said, because it is what it is and I have lived it. Unlike, Hardmill and Scott-bob, talking about something they really don't know anything about.
So, that is how this thread got started. I would pop in and out now and then but haven't been around for a long while now. I have other idea’s going on now.
The end deal is, you have to have sections of experts in specific fields to do HSM, as I would think is probably true with most any involved process. No one man is an Island, only one of many. A programmer cannot know everything I know about tooling, chatter, frequencies, flexibility, etc just like I cannot know diddle about programming, and I don't care to know programming and don't claim to. It would be ridiculous to even pretend so.
As time goes by, I mean as the years go by, I find out more and more that this is true. Programmers are the worst about thinking they know cutting tools and processes and it really messes things up. They think because they can create a program that they know tooling too? That is rediculous. I have talked to hundreds of programmers and dealt with many engineers, managers, supervisors, lead men, that say they know about HSM, chatter etc. But I can tell you, most don't have a clue what I am talking about when I get down into it and then they defensive towards me beause of it. Myself, I don't know programming, supervision, managing, engineering and I certainly don't try to make anyone think I do. Heck even tool salesmen don’t know about chatter and dynamics. I have not met any yet that really understood what I was talking about except those that have had that training, and they are few and far between. Sales people are not trained in dynamics, it would be to costly, so they have specialist, phd's, etc. Those are the guys to talk to.
Here is an example: I worked for a large company running a CNC lathe. To make a long story short, the tooling sales person was selling the company some dampened bars to prevent chatter on a I.D. Threading process I was doing. The head of tooling in the shop I was working in came by and asked where to cut the bar off so it would fit in the machine. Well, the bottom line was, it is a dampened bar. You can’t just cut it in half and expect it to work. He was a former CNC lathe or Milling guy, new a little programming and didn't know diddle about cutting tools or dynamics, but they made him the head of tooling for some reason.
Well they didn’t listen to anything I said, so they cut it in half, clamped it in the dampened area of the bar and the chatter got worse. They did this on two machines. I tried to tell them but they would not listen nor did they understand at all. Again, the programmers, the head tooling guy, the manager and the supervisor did not have the training to know this. The worst part about all this was that the tooling salesman didn’t even know that we can’t do this to that bar. I ended up having to get a specialist from the tooling company, and this company is a worldwide seller of cutting tools to thousands of shops. I couldn’t believe what I was seeing.
Finally they sent a specialist regional representative in and I explained to him what was going on. He had no choice but to agree with me and get rid of that bar and go back to the one I wanted in the first place. This was $6,000 later in bars, they had 4 of them, not to say the money wasted in scrap parts due to the chatter marks on a threaded part. They fired the sales person, I guess he became the fall guy on that one. Needless to say at our shop, programming, tooling, manager and supervisor didn’t thank me, didn't shake my hand, pat on the back, nothing. They just covered it up and acted like nothing ever happened. Of course in their minds I was the bad guy here, funny how that works.
What they didn't know about Dampened bars: The dampened bar in this case was 22 inches long and 2-1/2” in diameter. This as are all sampened bars, are meant to be long for long reaches. 4-10 times diameter ratio. This style bar has a mark about 7 inches from the front of it, etched line, that means 'Do not to clamp in this area", the dampener inside is in this area.
It has another line etched more towards the back end at about 16” from the front. That mark is to tell you "Not to cut this bar any shorter than this line", because it is a tuned bar and requires the mass to dampener ratio to be held in order to dampen. Freqeuncy stuff. Needless to say, they cut the bar at 15inches, 1" below the mark and then we had to clamp the bar in the dampened area where it said not to. $2,000 down the drain for that bar. Of course these rules don't come with the bar, you have to know about it. or ask for a drawing on it, or do what they did, rely on the tooling vendor. I don't rely on any tooling vendor unless I drill them first.
The thinking of these guys in my shop was that they were using integrated dampened bars on other machines and they worked great, so this will work even better. But the fact was that they couldn’t modify those dampened bars on the other machines because they were integrated bars. They were one piece assemblies with a quick change interface on it so it could not be modified. I don’t think to this day that they understand it all. What they thought would be awesome turned out to be deadly.
07-26-2010, 01:39 AM
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