the milk box we are talking about is called Tetra Pak Bao. Why is it called Tetra Pak? Because Tetra Pak has been revising the design since 1943. The most common, of course, is the aseptic Tetra Pak brick that wraps milk.

four-layer structure

tearing open the wrapping paper of a carton of milk, you can see that there are four layers: the outermost printing layer, the middle layer of cardboard and aluminum foil, and a layer of plastic film glued tightly to the aluminum foil for complete sealing. There is also a saying that the seven-layer structure takes into account the adhesive layer between the layers.

multicolor overprinting

the most noteworthy design of Tetra Pak is of course the printing layer. For this kind of mass packaging printing, if the factory prints all the colors at once, the equipment requirements will be too high. So there is a very cost-effective method, the equipment is still the same device, each time with a different printing version ~ this is "multicolor overprinting", each time only one color is printed, and the superposition of different colors can produce more colors. Printing up to 6 colors can produce all colors.

install the brush plate

the printing drum is a fixed equipment. For Tetra Pak packaging that needs to be printed, the workers take the printing plate of each color and attach it to the printing drum.

this is the first color printed.

the color printed the second time.

check under the flash light

if you let the printing equipment run at full speed, it is invisible to the naked eye. In order to better observe the printing effect, you need to use the flash lamp. Let the time interval of the lights be fixed, then each time you see the picture will stay on a printing screen, so you can see whether the printing is crooked many times. The small color blocks on the box are used by printers to see if there is any overlap and deviation.

the widely circulated rumors that color combinations represent different additives can be put to rest! There is also a rumor about the color patch on toothpaste, which has been refuted in the previous writing "the making of color strip toothpaste". This color block is used for photoelectric positioning.

Printing layer + Paperboard layer

after baking and heating the paperboard layer, the printing layer and the cardboard layer of the outermost plastic material are quickly bonded together by drum extrusion.

Printing layer + cardboard layer + aluminum foil layer

look at the bonding equipment below, the left drum is the aluminum foil layer, the middle is the adhesive layer, the right drum is the printing layer and cardboard layer that has been bonded together, the two sides are sprayed with liquefied glue, and the drum glues the three layers of Tetra Pak together by extrusion.

Printing layer + cardboard layer + aluminum foil layer + plastic film

the last drum bonding extrusion, the left drum is a plastic film, the middle is still an adhesive layer, the right is the printing layer, cardboard layer, aluminum foil layer that has been glued together, and the two sides are still sprayed with liquefied glue, and the drum will glue all four layers of Tetra Pak together through extrusion.

cutting ingredients

the Tetra Pak package, which is super large after bonding, is cut into small rolls that can be packed independently by the cutting machine.

crimping process

the Tetra Pak package of a single roll is sent to disinfection and sterilization, then it enters the packaging process, and the Tetra Pak package is gradually crimped together by machine.

see Tetra Pak packages gradually coming together.

filling and sealing

Wearing our petite evening dresses will allow you to achieve just the look you wanted. Check these fabulous sellections.

after the edge is hot sealed, you can fill the beverage, one bag at a time, cut and seal the bottom and top of the upper and lower packaging, fill again, seal the bottom and top of the upper and lower packaging again, repeat the operation to complete the beverage filling and packaging sealing.

the last single pack of drinks is sent to the packing assembly line.

and so on! Cast also has something to say

little cutie that the flashlight doesn't understand, let me explain. First of all, when talking about the special structure of the human eye, you can understand that the human eye is actually taking a single picture all the time, because we are born with "visual residue", so we will string the pictures together, so that the pictures shown in our minds move continuously.

but if you want to move, you have to meet one more condition: only when the number of frames of the picture exceeds 10-12 frames (the number of frames is how many pictures appear in one second), the visual remnant will be regarded as continuous motion. For example, I set the following fan picture at 15 frames, and you can see that it is spinning continuously.

now I adjust it to 6 frames, and I find that I feel stuttered.

for example, fluorescent lamp, in fact, it is flashing at high frequency, but the number of frames is too high, and we think it is always bright when we add the visual residue. And the movie projectors are also full of pictures, which are made up of our own brains for continuous movement. In addition, the picture benchmark used in the movie is usually 24 frames, that is, 24 photos per second, but Ang Lee used 120 frames to shoot "Billy Lynn's halftime War". Interested little cutie will find that the whole picture gives you a … It's a weird experience.

this article is reproduced from Cast's official account "interesting Manufacturing". If you want to understand various machining and manufacturing processes, scan the code and follow the author.

the Gif in the article is intercepted from:

Discovery "How it\'s.Made "S06E06