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Material Considerations

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  • chrisbarrattuk
    Hello everybody. For my 4th year engineering group project we have been asked to make a 3D rapid prototyper and have decided to go down a route similar to
    Message 1 of 8 , Jan 21, 2009
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      Hello everybody.

      For my 4th year engineering group project we have been asked to make a
      3D rapid prototyper and have decided to go down a route similar to
      afogassa.

      Last night i went to a talk by the intitute of mechanical engineers
      and the lecturer used to be at the forefront of rapid prototyping
      research (before he forked into studying termites!!). This is what he
      recommended we did:

      - As a powder base use the same nylon powder that they use for laser
      sintering. It is relatively expensive, but can only be recycled 5
      times for the laser sintering before it has to be chucked out. It
      costs companies money to dispose of this powder so they are likely to
      give it to us for free - and it is good enough for our application.

      - Next use a standard black ink to spray the template onto the powder
      in the same way afogassa does.

      - Next, flash the surface with an infra red light. If you manage to
      input the perfect amount of energy the areas in black will melt the
      nylon, fusing it together and the white plastic will not (due to the
      difference in absorbtion coeficcient of IR between the dark and light
      areas).

      Aparently you end up with a strong, elastic nylon model, with the
      impregnated black ink having little effect on propeties. Furthermore
      you could still follow the dental plaster/maltodextrin route as well
      if you wanted to make moulds for example.

      The main problem i can predict is ensuring that the whole surface gets
      an even spread of IR radiation, and finding a IR source hot enough to
      melt the plastic within a second or two (was thinking maybe using a
      halogen hob from a cooker for example).

      What does everyone think, any ideas?

      Chris
    • chrisbarrattuk
      Could even just attatch a single bulb from a heater like this: http://uk.youtube.com/watch?v=zPZODedZkIE that can heat it whilst applying a new layer, can then
      Message 2 of 8 , Jan 21, 2009
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        Could even just attatch a single bulb from a heater like this:
        http://uk.youtube.com/watch?v=zPZODedZkIE that can heat it whilst
        applying a new layer, can then just fiddle with heater voltage and
        gantry speed to find an optimum...
      • Fernando Muñiz
        Well it s a novel idea, but having researched into FDM (fusion deposition modeling), I know what a hassle fused polymer can become when deposited layer by
        Message 3 of 8 , Jan 21, 2009
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          Well it's a novel idea, but having researched into FDM (fusion deposition modeling), I know what a hassle fused polymer can become when deposited layer by layer.
          you have dilatation and shrinkage to deal with on top of consistent inter-layer bondage. Then of course, I've never researched into nylon powder, so who knows..

          As for the IR light source, you have an issue of focus. The surface size of your layer is limited to the temperature surface map the IR source can produce.
          This temperature map has also an issue of consistency throughout the surface. You risk having spots with bubbles and chemical dissociation (to hot) and others with imperfect melting and granulation (to cold).
          If you want the process of melting to be fast, you need a lot of power, maybe a ceramic heater plate like the ones on a stove would do?
          If you have patience and money, you could use a powerful IR laser

          Difficult tech IMHO

          On Wed, 2009-01-21 at 11:28 +0000, chrisbarrattuk wrote:
          Could even just attatch a single bulb from a heater like this:
          http://uk.youtube.com/watch?v=zPZODedZkIE that can heat it whilst
          applying a new layer, can then just fiddle with heater voltage and
          gantry speed to find an optimum...




        • chrisbarrattuk
          Well it s a novel idea, but having researched into FDM (fusion deposition modeling), I know what a hassle fused polymer can become when deposited layer by
          Message 4 of 8 , Jan 21, 2009
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            Well it's a novel idea, but having researched into FDM (fusion
            deposition modeling), I know what a hassle fused polymer can become
            when deposited layer by layer.
            you have dilatation and shrinkage to deal with on top of consistent
            inter-layer bondage. Then of course, I've never researched into nylon
            powder, so who knows..

            [[[I'm asuming that the dilation and shrinkage is related to the
            properties of the powder, and as the powder is produced by SLS
            companies - who have put alot of research into this, hopefully the
            properties will be good.]]]

            As for the IR light source, you have an issue of focus. The surface
            size of your layer is limited to the temperature surface map the IR
            source can produce.
            This temperature map has also an issue of consistency throughout the
            surface. You risk having spots with bubbles and chemical dissociation
            (to hot) and others with imperfect melting and granulation (to cold).
            If you want the process of melting to be fast, you need a lot of
            power, maybe a ceramic heater plate like the ones on a stove would do?
            If you have patience and money, you could use a powerful IR laser

            [[[ A halogen strip from a halogen heater i'm hoping would have a
            uniform heat output along the strip, you can then traverse it across
            the bin at a constant speed applying the same amount of heat energy to
            all areas of the bin. There are lots of variables you can fiddle with
            e.g. layer height, traverse speed, and the element voltage to optimise
            the end propeties - also a halogen strip is conveniently 240mm long,
            only slightly wider than a piece of A4. As for the laser -
            unfortunately i dont have the money, and the university wouldnt allow
            it anyway (stupid risk assesments!)]]]
          • Fernando Muñiz
            Well, it s worth trying, specially if somebody from the field has thought the idea to be good. One question: isn t SLS performed by laser? Good idea about the
            Message 5 of 8 , Jan 21, 2009
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              Well, it's worth trying, specially if somebody from the field has thought the idea to be good.
              One question: isn't SLS performed by laser?

              Good idea about the halogen strip traveling over the layer. You could do the sintering in several fast passes.

              On Wed, 2009-01-21 at 15:54 +0000, chrisbarrattuk wrote:
              Well it's a novel idea, but having researched into FDM (fusion
              deposition modeling), I know what a hassle fused polymer can become
              when deposited layer by layer.
              you have dilatation and shrinkage to deal with on top of consistent
              inter-layer bondage. Then of course, I've never researched into nylon
              powder, so who knows..

              [[[I'm asuming that the dilation and shrinkage is related to the
              properties of the powder, and as the powder is produced by SLS
              companies - who have put alot of research into this, hopefully the
              properties will be good.]]]

              As for the IR light source, you have an issue of focus. The surface
              size of your layer is limited to the temperature surface map the IR
              source can produce.
              This temperature map has also an issue of consistency throughout the
              surface. You risk having spots with bubbles and chemical dissociation
              (to hot) and others with imperfect melting and granulation (to cold).
              If you want the process of melting to be fast, you need a lot of
              power, maybe a ceramic heater plate like the ones on a stove would do?
              If you have patience and money, you could use a powerful IR laser

              [[[ A halogen strip from a halogen heater i'm hoping would have a
              uniform heat output along the strip, you can then traverse it across
              the bin at a constant speed applying the same amount of heat energy to
              all areas of the bin. There are lots of variables you can fiddle with
              e.g. layer height, traverse speed, and the element voltage to optimise
              the end propeties - also a halogen strip is conveniently 240mm long,
              only slightly wider than a piece of A4. As for the laser -
              unfortunately i dont have the money, and the university wouldnt allow
              it anyway (stupid risk assesments!)]]]




            • afogassa
              ... diy_3d_printing_and_fabrication@yahoogroups.com, chrisbarrattuk ... make a ... he ... to ... powder ... light ... gets ... to ... There is a company that
              Message 6 of 8 , Jan 21, 2009
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                --- In
                diy_3d_printing_and_fabrication@yahoogroups.com, "chrisbarrattuk"
                <hotnutas@...> wrote:
                >
                > Hello everybody.
                >
                > For my 4th year engineering group project we have been asked to
                make a
                > 3D rapid prototyper and have decided to go down a route similar to
                > afogassa.
                >
                > Last night i went to a talk by the intitute of mechanical engineers
                > and the lecturer used to be at the forefront of rapid prototyping
                > research (before he forked into studying termites!!). This is what
                he
                > recommended we did:
                >
                > - As a powder base use the same nylon powder that they use for laser
                > sintering. It is relatively expensive, but can only be recycled 5
                > times for the laser sintering before it has to be chucked out. It
                > costs companies money to dispose of this powder so they are likely
                to
                > give it to us for free - and it is good enough for our application.
                >
                > - Next use a standard black ink to spray the template onto the
                powder
                > in the same way afogassa does.
                >
                > - Next, flash the surface with an infra red light. If you manage to
                > input the perfect amount of energy the areas in black will melt the
                > nylon, fusing it together and the white plastic will not (due to the
                > difference in absorbtion coeficcient of IR between the dark and
                light
                > areas).
                >
                > Aparently you end up with a strong, elastic nylon model, with the
                > impregnated black ink having little effect on propeties. Furthermore
                > you could still follow the dental plaster/maltodextrin route as well
                > if you wanted to make moulds for example.
                >
                > The main problem i can predict is ensuring that the whole surface
                gets
                > an even spread of IR radiation, and finding a IR source hot enough
                to
                > melt the plastic within a second or two (was thinking maybe using a
                > halogen hob from a cooker for example).
                >
                > What does everyone think, any ideas?
                >
                > Chris
                >

                There is a company that developed something similar to what you are
                talking about.
                They print a negative mask on glass then put the mask on top of
                the build chamber filled with nylon sintering powder then turn on a
                ir lamp, after the powder gets solid they screap the mask off and
                print a new one.
                there is one problem to deal with, "shadows" becouse of the glass
                thickness.
                Also there is a US university that developed a system called laser
                inhibition sintering, they use the same printing processes, but uses
                salt water to print a negative image on the powder(nylon powder I
                guess) and apply a heat source(ir lamp)to the printed layer, then
                only the non saturated powder gets fused together.
                On laser sintering processes they use nitrogen filled chambers to
                prevent the powder from oxidazing and from set everything on fire.
                I do have a 50w laser cutter and I was thinking about going the
                sintering way but I need to upgrade the software controller to do
                raster before trying that.

                Fogassa
              • Lance Arvidson
                Which university do you go to? ... From: chrisbarrattuk Subject: [diy_3d_printing_and_fabrication] Material Considerations To:
                Message 7 of 8 , Jan 21, 2009
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                  Which university do you go to?

                  --- On Wed, 21/1/09, chrisbarrattuk <hotnutas@...> wrote:

                  From: chrisbarrattuk <hotnutas@...>
                  Subject: [diy_3d_printing_and_fabrication] Material Considerations
                  To: diy_3d_printing_and_fabrication@yahoogroups.com
                  Received: Wednesday, 21 January, 2009, 11:15 AM

                  Hello everybody.

                  For my 4th year engineering group project we have been asked to make a
                  3D rapid prototyper and have decided to go down a route similar to
                  afogassa.

                  Last night i went to a talk by the intitute of mechanical engineers
                  and the lecturer used to be at the forefront of rapid prototyping
                  research (before he forked into studying termites!!). This is what he
                  recommended we did:

                  - As a powder base use the same nylon powder that they use for laser
                  sintering. It is relatively expensive, but can only be recycled 5
                  times for the laser sintering before it has to be chucked out. It
                  costs companies money to dispose of this powder so they are likely to
                  give it to us for free - and it is good enough for our application.

                  - Next use a standard black ink to spray the template onto the powder
                  in the same way afogassa does.

                  - Next, flash the surface with an infra red light. If you manage to
                  input the perfect amount of energy the areas in black will melt the
                  nylon, fusing it together and the white plastic will not (due to the
                  difference in absorbtion coeficcient of IR between the dark and light
                  areas).

                  Aparently you end up with a strong, elastic nylon model, with the
                  impregnated black ink having little effect on propeties. Furthermore
                  you could still follow the dental plaster/maltodextri n route as well
                  if you wanted to make moulds for example.

                  The main problem i can predict is ensuring that the whole surface gets
                  an even spread of IR radiation, and finding a IR source hot enough to
                  melt the plastic within a second or two (was thinking maybe using a
                  halogen hob from a cooker for example).

                  What does everyone think, any ideas?

                  Chris



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                • chrisbarrattuk
                  University of Southampton, England.
                  Message 8 of 8 , Jan 22, 2009
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                    University of Southampton, England.
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