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Creating an Air-Hockey table but to slide Tortilla Chips over

  1. Nov 16, 2009 #1
    Here's my problem:

    I have a giant oven that has 3 layers of conveyor belts in it. Tortilla chips are sent through the oven starting at the top layer, and then passed down to the second conveyor (which runs reverse compared to the top one) to get both sides of the chip to cook. After the second layer, the chips are dumped onto a chute (similar to a half-pipe) and slide down to the 3rd, and bottom belt. Sometimes, on this chute, the chips get stuck (not dry enough to slide down), and then build up clump that I have to shut down the entire oven to clean out the clumps. Is it possible to build my chute (half-pipe) with preforated holes, and connect it to compressed air or a blower to mimic an air-hockey table? I think creating an air-bed for the chips to gently slide over would alleviate any problems with them sticking to the chute (since theoretically, they won't touch the chute)

    I have a restaurant-style (Triangle) chip, that weights 3.6g. Square dimensions are 3.25"(length) x 4.5" (max width) of the chip. I'm planning on cutting 1/8" holes that would be spaced 1/2" x and y apart from each other.

    Area of holes:
    pi*(.0625)^2 = .0123in^2
    Square-izing the triangle tortilla chip would result in the chip covering 41 holes, and covering 15 semi-circles.
    (.0123)x41 + (.00614)x15 = .5964

    F=(.0036kg)(9.8m/s^2)=.03528 N
    .03528 N = .00793126 lb of force

    (.00793126) / .5964 = .0133 psi

    Is this accurate? Any help or more variables that I would need to account for would be appreciated.
  2. jcsd
  3. Nov 16, 2009 #2


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    From a textbook (i.e. homework, lots of simplifications), sure it seams reasonable. Create a deltaP over that area to offset the weight of the chip.

    In real life though, you're going to have lots of uncertainties to deal with. One, the chip will not at all times cover the right amount of holes. Two, pressure acts normal to the surface, so an uneven chip will cause force to be directed at angles other than straight up.

    Most importantly, depending on how long you are perforating this chute, you may need a fairly sizable pump. You'll need to calculate the amount of flow needed to generate that pressure, taking into account losses through the holes (0.0133 psig in the "plenum" will not get you 0.0133 psig on the chip).
  4. Nov 16, 2009 #3
    If I increase the amount of pressure coming out of the holes, (i.e. increasing the amount of "lift" on the chip), so that way if its not covering all holes, it will still glide down, would that work? As far as #2, how significant of a problem do you think that will be? If a chip comes down unevenly/folded, will the air cause the chip to go in a variety of directions possibly negating the entire reason of attempting to put preforated air holes in the chute? Basically, would I solve parts of the problem, but the air could also act in a way to create the same problem I'm trying to solve?

    What does deltaP relate to? Change in pressure, pounds?

    I was thinking of using compressed air. We have a compressed Air pump that pipes throughout the plant, therefore I wouldn't need a fairly sizable pump right next to or underneath my oven. The chute is sized at 44" width, and about 12" length. I would need to preforate air holes in only 16" width, 12" length. How do I calculate the amount of flow needed to generate that pressure?

    Is the only solution to try a small sample piece in the chute, to see how it reacts with real-life variables?
  5. Nov 16, 2009 #4
    Besides air, there are other possible solutions such as surface coatings, vibrating the chute, installing an oscillating rake or auger, making a circular chute that rotates.
  6. Nov 17, 2009 #5


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    Science Advisor

    If this is something easy to try out, then you might as well just go ahead and try it. If you have the compressed air on hand, then creating a perforated chute isn't too much of an investment. Just make sure you have a way to control the pressure or you might have chips all over the place.

    One a side-note, is there any way to handle the root cause of the problem? That being the fact that sometimes chips don't get cooked enough.
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