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Any good papers on CAD CAM

Discussion in 'Biomechanics, Sports and Foot orthoses' started by Kerrie, Aug 25, 2010.

  1. Kerrie

    Kerrie Active Member


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    Hi all,
    I'm currently doing some research on CAD CAM and orthotics at the moment. Does anyone have any good papers that they can suggest or opinions?
    Thanks :D
     
  2. Kerrie, we as a profession are having enough trouble discussing the use of OTC device v´s a custom device. or indeed how an orthotic device even works . I don´t think you will find research that compares a milled device v´s a pressed device.

    But in saying that I believe than CADCAM is the future of orthotic manufactor and will be investing my Krona in a setup within the next while. I believe this because it should give me more control over the end produce, ie a 6mm 15 degree will be 6 mm 15 degrees not a close approximation. I also think that having different plastic flex levels in a device is something I want to look more closely at. There was a paper or discussion on this I read somewhere. Found the link HERE At the moment I grind away material again not specific.

    Not sure that helps
     
  3. joejared

    joejared Active Member

    6mm is never 6mm, even with the most precise of system. ,It can be 6mm +- a specified tolerance. Then, you have to consider the accuracy of the machine, characteristics of the cutting tool, flexibility of what's being cut, how much it will change shape while it's being cut, and finally, cutting speeds and feeds and how close to perfect the supporting structure (jig) is in holding the material and alignment of the top and bottom cutting surfaces. Not all polypropylene sheets have the same machining characteristics, which sometimes causes other problems that ultimately affect the device characteristics.

    As to 15 degrees, relative to what, and about which axis?

    For one new customer making hard shell devices, plastic thickness entered is 0, and the system calculates thickness based on rigidity and patient weight. I'm actually discouraging manual entries of plastic thickness , although calculated thickness is reported and can be overidden. In terms of thickness alone, they have control over rearfoot, overall thickness, lateral thickness, feathering margins and edge thicknesses for lateral, medial and distal edges. As for tolerances, if a system can't maintain +-0.5mm tolerances on target altitudes and thickness with polypropylene, there's a problem. My own system's goals are +-0.15mm and usually produce at worst, +-0.3mm.

    For all systems capable of machining materials as hard as delrin, tolerances improve dramatically with delrin over polypropylene simply because polypro will stress relieve while cutting and because delrin is a more rigid material. For one project, I'll be machining HDPE for use with a new product line for my customers as a vacuum chuck for full length EVA devices. From what little I have worked with this material, it seems slightly more flexible than polypro and suggests slightly higher material thickness requirements if it's used for orthoses, but otherwise it has similar machining characteristics to polypro.

    As for the new lab who doesn't enter an actual material thickness, here is one coding example, which hardly touches pre-algebra in terms of math skills.
     
  4. Phil Wells

    Phil Wells Active Member

    Kerrie

    Have a look at the prosthetic industry - there are a few papers around - sorry but I don't have the references.

    Cheers

    Phil
     
  5. Greg Quinn

    Greg Quinn Active Member

    Here's one that might be of interest to you Kerrie.
     

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