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  1. #1
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    Default Need your help guys.

    Good evening! I'm a machine manufacturing student in my last year and for my main project i have to do the machining process of this parthydraulics-turned-parts-1.jpg.
    The problem is that the teacher gave me only this image and no more information and the problem is that i cant start the project only with this ..I need to know the assembly so i can tolerate the surfaces by what they do , decide if there is a thermal treatment needed etc..
    I'd like to ask you guys if any of you know what this is and what it does . The main problem is that U shaped millings because i'd say it is a hydraulic piston or something but the millings has to do something important.
    What i've gathered so far is that this picture can be found here and here: Hydraulics machined parts, turning components for aerospace
    (Examples of our machined parts For lifting equipment we produce: Hydraulic pistons used in control joysticks for caterpillar tracks and for mechanical digger arms, in ETA 100, plus TTH and rectification.
    Rehtek precision machines valve parts from metals and alloys
    The fact that here is in the valve category
    I'd be great if you could provide any data , thank you !

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    Maybe your teacher is trying to get you to use your imagination? As he or she has given no other information, you can go wild. As long as the part looks like the photo in the end, it cant be wrong, as that is the only criteria given. It does look like a hydraulic valve, the cutouts provide a smooth flow from closed to open.

  3. #3
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    "GD&T" please search the forums.

  4. #4
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    Ask Rehtek what it is. If you explain your situation, they should be willing to help. They say it is made with one chucking, so it is probably made on a CNC lathe with live tooling to cut the notches.

    Since you are new to the forum, you get some slack, but in the future the rules say that the title needs to describe the subject so people can find it in a search. Spelled out in the stickies.

    Bill

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  6. #5
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    What Bill says ...

    If I had a jack wagon teacher like that, I would buy the part and turn it in and then spend my time machining something that I wanted for my own use.

    At a minimum I would call Rehtek and see if they had any scrapped parts of this type that you could have and turn that in.

  7. #6
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    Hey didn't you guys see, this CallyTech part is French. That means it's not possible to make it. Or buy it. Well not now.... Come back tomorrow and it might be possible. Well, how many do you need? You say your father was from this region? Hmmm there might be one in the back. Let me check....

    Alexander, PocoLoco is totally right, if your instructor didn't give more information about the application, he or she wants you to think about how a part like that would be made in general. That includes both how to make the features and what are the order of operations. The latter is important sometimes as if you go from lathe to mill for example, you may break the symmetry for one feature, eg milling into the cylinder, and now all the other milled features, like off axis holes need to be based on the arbitrary plane your first mill operation established. I asked exactly this type of question in a series of job interviews I just conducted for an engineering, and ended up hiring the person who gave the clearest answer on how to machine the pictured part (as well as giving the best answer on my software questions, and heat transfer questions as it happens!) If you say, OK it's a hydraulic piston, then look up typical tolerances or perhaps those groves are for piston rings or seals and you look up tolerances for those.

  8. #7
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    Actually.. among the information any GOOD teacher is seeking is evidence that you are capable of USING ALL of your brain, are AWARE your knowledge is incomplete... that you KNOW you have unanswered questions and NEED to get more information..

    Rather than guess, "show your work". EG: "I needed to know.. the reason is.. the possible parameters are.. I made this set of choices only to get to one of several possible answers I know that different parameters than those PREsumed (never ass u me 'ed) would drive a DIFFERENT answer.

    The second-best Officers I ever trained did not make mistakes.

    The first-best DID make mistakes. They just recognized them as such and CORRECTED them faster than normal.

    This is valuable.

    Because life is not so generous as to LIMIT a person to dealing only with his OWN mistakes. Yah have to be able to deal with the mistakes of others.

    Or in the Combat Arms realm? More often some rude bastard trying to wipe you and your command right off the planet, and damned seldom willing to share the how, when, and why of his plan with his enemy. Certainly not in advance.

    All you can do is turn his actions into just one more "mistake"!

    And "mistakes" you are expert at handling fast and well.
    To your team's advantage. Not his.

    Business world is much the same. Hopefully, nobody has to die.

    But some surely do EAT better than others and - more importantly by far - get the attention of the more interesting blanket-sharers and baby parents.

    "Case anyone missed it? We don't individually get to live forever, y'see.
    What carries-on is another form of "team".

    Learn. Grow. Pass it on.


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    Alexander, as a machine manufacturing student, you must think of this part from a manufacturing standpoint. From a machinist standpoint, materials, dimensions, tolerances and etc are important. Exactly why your teacher did not include them. I like what thermite said about second best officers. All along we are taught that mistakes are bad, and making less of them makes you better at what you do. True to a point, but if you avoid new things, to avoid making mistakes, you are not learning. Trying things, making mistakes, and correcting them as you go along, is one of the most important processes of life.

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    Quote Originally Posted by rcoope View Post
    Hey didn't you guys see, this CallyTech part is French. That means it's not possible to make it. Or buy it. Well not now.... Come back tomorrow and it might be possible. Well, how many do you need? You say your father was from this region? Hmmm there might be one in the back. Let me check....

    Alexander, PocoLoco is totally right, if your instructor didn't give more information about the application, he or she wants you to think about how a part like that would be made in general. That includes both how to make the features and what are the order of operations. The latter is important sometimes as if you go from lathe to mill for example, you may break the symmetry for one feature, eg milling into the cylinder, and now all the other milled features, like off axis holes need to be based on the arbitrary plane your first mill operation established. I asked exactly this type of question in a series of job interviews I just conducted for an engineering, and ended up hiring the person who gave the clearest answer on how to machine the pictured part (as well as giving the best answer on my software questions, and heat transfer questions as it happens!) If you say, OK it's a hydraulic piston, then look up typical tolerances or perhaps those groves are for piston rings or seals and you look up tolerances for those.
    First, to correct myself, it says the part is made in one machining, not a single chucking. I don't think the grooves are for rings. They are more likely labyrinth grooves, which means that the tolerance on them is large but the tolerance on the OD is very tight because it has to be a very close fit in a cylinder. That says a hardened and ground part and a honed cylinder. That limits the material selection to hardenable ones and if it is used in a properly maintained hydraulic system, corrosion resistance should not be an issue because the oil protects it. The problem there is that often people do not do proper maintenance and get water in the system.

    If they are labyrinth grooves, that implies that the piston is used in a low friction application where the drag of piston rings or O rings could not be tolerated.

    The grooves that are interrupted are puzzling.

    Re French companies, My basic view is that nothing is simple to a Frenchman. If you ask a German for directions, he will say "Go two blocks and turn right." A Frenchman will give you a twenty minute lecture about the history of the area, why your destination is there, and on and on.

    Bill


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