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Why are ice cubes not really cubes, but trapezes?

  1. Nov 28, 2013 #1
    In other words, why are ice cubes trays shaped like the left-hand figure instead of the right-hand one?


    If the cube were more square-shaped like the second figure, it would have more volume, thus having more ice in total and keeping the drink cold for longer. I also suspect it would be less likely to slip from people's hands. So why not?
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  3. Nov 28, 2013 #2


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    Well beside the fact that I have seen ice cube trays in many different shapes I will pretend that you are right, All ice cubes are shaped as you say.

    Release, the sloped walls of the tray make it much easier to get the ice out.
  4. Nov 28, 2013 #3


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    Volume of ice is only one consideration in engineering an ice cube tray. I can see the offset shape (1) provides more surface area for thermal transfer and, perhaps more importantly, (2) facilates removing the cubes from the tray.

    What do you think?
  5. Nov 28, 2013 #4
    I apologize for not living in the same country as you, where you have more variety. In Brazil, all ice trays I can remember are indeed shaped as I described.

    I was thinking about the issue since I posted the thread and I reached the same two conclusions. Are there any more reasons you can think of? Thanks!
  6. Nov 28, 2013 #5


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    Working with the premise to maximize 'functionality', the items I can think an engineer would consider during design would be:
    1) Ease of filling.
    2) Speed of making ice.
    3) Ease of removing ice.
    4) Chilling performance.

    These are the goals I can think of. There are easy answers to items when taken one at a time, but best solutions for each item can contradict best for others. Maximizing surface area is good for #2, and also #4 but only if rate of chilling is considered better than lifespan of ice cube. Trapezoid assists in #3, and I'm not sure, but maybe slopes also help ease of filling (#1) by reducing 'backsplash'...? Not sure about that one!

    So unless you can think of any other 'goals' of the utopian ice cube tray, I'd say these four topics are what the engineers are doing max/min analysis on based on the goals/bias of the end result.
  7. Nov 29, 2013 #6


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    They might be easier to manufacture that way. But that's just a guess. I was also thinking that because ice expands, the cubes might automatically eject themselves a tiny fraction during the freezing process, making them easier to remove.

    A quick google search indicates you can get ice cube trays that have all sorts of interesting shapes.

    Here's a cool assortment:

    20 Unusual and Creative Ice Cube Trays

    My current set of ice cube trays create 1/2 inch diameter half cylinders. They are awesome for putting in small necked plastic pop bottles, which I re-use for years as water bottles.
  8. Nov 29, 2013 #7
    And the marketing department could or would negate items 1,2,3,4 for look, packaging, return on cost of production, sex appeal and whatever criteria they would consider to make their product stand out from the rest. Engineering would be predominant only for "can we make it" and how much does manufacturing cost".
  9. Nov 29, 2013 #8
    The shape also helps with stacking, keeping transport costs (from whatever Chinese manufacturing plant actually makes them) down.
  10. Nov 29, 2013 #9


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    I have the impression that some ice making machines produce cubes, not trapezoial shapes. The clear ice cubes are made by repeatedly layering thin films of water that then freeze to form the cubes.
  11. Dec 1, 2013 #10


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    The shape not only helps release the ice from the tray but it also helps release the tray from the moulding machine that made the tray.
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