Why are some plastic bottles thicker than other? Surely the amount of plastic being user to mold a bottle is highly controlled
In: Engineering
It is plastic bottles for the same product or for different products? Different companies can choose to have different wall thickness on the bottle. It might cost a small amount more to have thicker walls but then you get a bottle that feels more substantial. Depending on what should be in the bottle the wall thickness might be diffrent
The surface structure of the bottle also has a huge effect on how thick the plastic feels. A smooth bottle will deform a lot simpler if you push on it compared to one that has some structure even if the amount of plastic is identical.
Bottle are not made directly from liquid plastic where you put food them. You mould a PET preform and heat up part of them and blow up in the bottling plant. They look [like this](http://sc04.alicdn.com/kf/HLB1RmYzVmzqK1RjSZFLq6An2XXav.jpg).
This makes the transport volume a lot smaller to purchase a full bottle. It also makes the required equipment a lot cheaper and simple to handle then if you did if from liquid plastic in the bottling plants. It is simple most efficient to a few factories that make lot of performers that supply many more bottling plants
They exist in different sizes and wall thickens for different bottles. So the bottling plant can if they order the same performer create bottles with a consistent thickness. It might be the case that some manufacturers could not the performer weigh what they wanted for some reason and will use a preformed with a bit more plastic, then a production batch make bottles with a bit thicker wall. You could do that with lighter performers but too thin a wall might bake the bottle fail was too thick only make it a bit stongers
But what thickest the bottle has will depend on what the manufacturers to have. It might change over time as a way to make a bit more money.
If you look at a supplier they produce performers with a lot of different weight for the same neck size so you can choose depending on bottle shape, volume, and the wall thickness you like [Just look here for the options](https://www.alibaba.com/product-detail/Factory-price-high-quality-28mm-30mm_60615877014.html?spm=a2700.details.deiletai6.1.4d537117i666jO)
depends on what’s being held and the actual plastic being used.
For drinks or food you want a thin plastic, you want it to be BPA and leech resistant, so the type of plastic you want to use changes, cleaning supplies or other chemicals need thicker bottles, or more resistant plastics, and since you´re clearly not going to drink bleach, it dosnt have to be food grade safe,
Also theres the issue of photosensitivity so some materials require the plastic to be a specific color or even fully opaque.
TL;DR : thickness, composition and transparency change depending on what you want to put inside if it.
A bottle, like any other item, is designed for a specific use and they will be adapted to it. Things that will affect the shape are:
– polymer type: different materials have different needs and may need to be more of less thick
– content: depending on acidity, light sensitivity, human consumption… the bottle material and shape may vary
-pressure: internal pressure (ie. carbonated drinks) require a sturdier bottle, that’s why coke bottle are thicker than water bottle
-cost: thicker bottles mean more material so higher production costs, manufacturers may want to use less material and/or different shapes that increase structural integrity
-appeal: the shape, size and feel of bottle depends a lot on who they are targetted to. Some people way feel that flimsy bottles look cheap and go towards better looking bottles, Fiji water for instance.
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