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  • ABS plastic vs Aluminum shaft on turbocharger applications

    Discussion in 'The main mechanical design forum' started by teknicalissue, Feb 11, 2015.

    1. teknicalissue

      teknicalissue New Member

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      Greetings!

      So I'm working on a project where I'm creating an electrical turbocharger and have a rather interesting question! Mind you, This is not my field of work so laymans terms are highly appreciated. Sorry for sounding a bit clueless!

      So overall, I'm creating an electrical turbo charger and reached a point where I'm keeping the compressor housing and wheel but might replace the shaft with ABS plastic instead of keeping the original aluminum shaft. The reason for this is that the turbo will be far away from the exhaust! this shaft will be installed on an angular bearing system and will spin at 150K RPM.

      Another reason is that I'm using a 3D printer and printing the shafts are going to be a whole lot easier than having them made.

      The diameter of the shaft will be 6.5mm slowly narrowing down to 6mm (6.5mm is the thread to screw in the compressor wheel).

      the shaft length will be about 5-6 inches and the wheel weight will be about 70 grams - 100 grams (depending on the compressor wheel I choose)

      Do you guys think the ABS plastic could handle it? It would speed up to full speed in about a second and hold the 150k speed for 4 seconds before slowing down.
       
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    3. Erich

      Erich Well-Known Member

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      Not a chance. 3d printing especially FDM has weak inter layer bonds. Your shaft will fly apart.

      also the plastic will change dimension with temperature much more than Aluminum which will add stresses the original design did not anticipate.

      By your own admission you are not qualified to engineer the system, and you are messing with energetic systems that can get people hurt if they fail. Please reconsider.
       
    4. Jitesh Nair

      Jitesh Nair Member

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      Can't comment on your idea but would recommend reconsidering the idea. Considerig the very high speed at which the system is going to operate, there is a pretty good chance you will damage the compressor wheel and blow up the compressor unit. Better leave high speed systems alone unless you have expertise in it.
       
    5. Robo-dog

      Robo-dog Member

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      3D Printing is awesome, but the application for what you are applying to is not a good one. There are different method of process to build a part, and a 3D Print is only good for low loads, very low loads. You are going to rip the design apart if you use this method.

      As for ABS Plastic vs Alumium...you have to consider the heat being applied to the material. The melting point is 212° F, and it is very toxic. For more info: http://www.plasticsmadesimple.com/DataSheets/ABS_MSDS_GP.pdf

      I agree with the temperature change, so it is best to leave it to Aluminum.
       
    6. Dave Archer

      Dave Archer Active Member

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      Completely stupid idea using plastics for such a dynamic system.
      ABS is brittle when cold and soft and unstable when warm.

      The start up torque and the slightest out of balance would shear off the soft ABS shaft, especially at 7mm dia.
      I am actually surprised that aluminium was used for the shaft also.

      You need a steel shaft.
       

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