Bumps on PET Bottles: Why & How?

  • Thread starter Thread starter abhiroop_k
  • Start date Start date
Click For Summary

Discussion Overview

The discussion centers around the design of PET bottles, specifically the presence of 'bumps' or feet on the bottom of the bottles. Participants explore the reasons behind this design choice, considering aspects of stability, manufacturing, and user experience.

Discussion Character

  • Exploratory
  • Technical explanation
  • Conceptual clarification
  • Debate/contested

Main Points Raised

  • Some participants suggest that the bumps improve stability during production, filling, and use, preventing the bottles from tipping over easily.
  • One participant notes that the bumps allow for better positioning in factories and maintain the bottle's shape during transport.
  • Another participant questions how multiple curved surfaces contribute to balance compared to a flat surface, proposing that they may provide a larger contact area.
  • It is mentioned that a flat bottom could deflect under pressure, creating instability, while the bumps provide a rigid structure that supports the bottle better.
  • Some participants discuss the potential issue of condensation creating suction on a flat surface, which could be undesirable.
  • There is a reference to alternative bottle designs that use a round rim with a recessed center, which also aims to provide stability without deformation under pressure.

Areas of Agreement / Disagreement

Participants generally agree that the bumps contribute to stability and manufacturing efficiency, but there is ongoing debate about the specific mechanics of how they enhance balance compared to a flat surface.

Contextual Notes

Some assumptions regarding the physical properties of materials and the effects of pressure on bottle design are present but not fully explored. The discussion does not resolve the specifics of how contact area influences stability in tipping scenarios.

Who May Find This Useful

This discussion may be of interest to individuals studying product design, materials science, or those curious about the engineering behind everyday objects like beverage containers.

abhiroop_k
Messages
42
Reaction score
0
why does the bottom of any average PET bottle have those 'bumps' instead of being flat?
does it have something to do with improving the balance, if so how?
 
Engineering news on Phys.org
abhiroop_k said:
why does the bottom of any average PET bottle have those 'bumps' instead of being flat?
does it have something to do with improving the balance, if so how?

What's a PET bottle?
 
i meant any plastic (other than glass) bottle generally used for storing cold-drinks, water etc.

:)
 
For stability during production, filling, and end-user use. The factory uses the feet to position the bottles in the factory for various purposes, the end-user relies on them so the bottle doesn't tip over easily. You'll see them in bottles which have internal pressure as the legs are much more rigid than a large flat surface and will remain fairly constant in their shape, making the bottle more stable when unopened, even after a long, bumpy transport.
 
thanks.
:)

how are multiple curved surfaces more suitable for balance as compared to a single flat one?
is it because they account for a larger contact surface area?
 
Also, condensation along with a single flat surface would create a suction to the table which is not desirable.
 
ahh nice hadn't thought of that! :)
 
abhiroop_k said:
how are multiple curved surfaces more suitable for balance as compared to a single flat one?
is it because they account for a larger contact surface area?

Well,
1) The bottles are plastic and so a flat bottom surface would, if unsupported, deflect under pressure creating a bubble on the bottom which would be horrible for stability. Not to mention it would be a pretty poor design as far as pressure vessels are concerned.

2) The legs have less overall surface area touching the table, but they are consistent in shape.

3) There are bottles which do not have the legs, but instead have a round rim along the bottom with the center recessed (so only the rim touches the table or other surface). This is for the same reason. A rigid area to stand the bottle on which will not deform under pressure.
 
  • #10
the pressure argument makes sense!
:)
i meant more contact area when a bottle tips over!
 

Similar threads

Vacuum furnace argon fill system — advice needed
  • · Replies 3 ·
Replies
3
Views
1K
Which Orientation is Worse for Leakage in a Glass Bottle?
  • · Replies 2 ·
Replies
2
Views
2K
A water-bottle demonstration of atmospheric pressure
  • · Replies 6 ·
Replies
6
Views
2K
Reusing Isopropyl Alcohol bottle for Drinking Water?
  • · Replies 21 ·
Replies
21
Views
6K
Why isn't my laminator sticking PET thin films together at high temperatures?
  • · Replies 2 ·
Replies
2
Views
2K
High School Can a skateboarder ride faster by holding a water bottle?
  • · Replies 123 ·
5
Replies
123
Views
7K
Bursting strength and compressive strength of cardboard tubes
  • · Replies 3 ·
Replies
3
Views
3K
Mold in Plastic Water Bottles? What does it eat?
  • · Replies 28 ·
Replies
28
Views
11K
Undergrad Is it possible to apply Gauss' law to a Klein bottle?
  • · Replies 1 ·
Replies
1
Views
2K
My glass beer bottle survived a fall from the 10th floor, how, & why?
  • · Replies 7 ·
Replies
7
Views
2K