Extrusion process; making "impacts" that shape our world
Its Thursday 14th of June 2018!
I feel so excited I don't know maybe it's due to the newly found knowledge or the fact that the world cup kicks off today!!
Well, not like I expect my country to win but my dad seriously believes that we can win it.. Sounds funny right?
I am not here to talk about football although I would like to discuss specially the food I love.
Well if you are someone like me who likes to take a good look at a food before I eat it then I can say we share something in common. I am that kind of person who takes a good look, turn the food left right and try to look at the composition of the food before I take it close to my mouth.
This same thing happened the first time I saw this meal, it was a flat place filled with these whitish and funny looking things, initially I didn't know what they were but if I had realized how much I was going to fall in love with this meal, I would have probably put it straight down my mouth.
The first thing that got my attention was the shape of the food I had to use my hands to pick this good-looking food that is in front of me it was round and plenty I loved the shape and the fact that they looked hollow with no trace of joint.
For this I placed it in my mouth and licked it before chewing, to me it was like the best thing after oxygen after I slowly ate everything using my hands. Well, not because I didn't know how to use a spoon but rather this food I was eating caught me by surprise. I even used it as a straw to suck in air. Lol
Don't mind me I was just a boy but the food was great I guess you want to know what this food was. Well if you choose macaroni then you are right. I am still in love with the food till today regardless of how it is cooked.
If you were following my post, my love for macaroni started from its looks down to its texture which made it find its way to my mouth and the shape got me doing all sort of things not forgetting it is smooth.
How did they arrive at the shape of macaroni? Have you ever thought of that? Some of you might say food processing. Yes, that is very much correct but food processing has lots to do but arriving at that shape is something out of the ordinary. Don’t forget I said they have no joint and are very smooth but hollow. Do you think they are handmade?
My answer is no, what if I told you that the process used in getting these shapes in engineering is called the extrusion process.
The extrusion process is applied not only in metal forming but also in food processing to get the best shape for macaroni.
This is an interesting article where you can one day answer that inquisitive kid you have who is dying to know how the macaroni and spaghetti are different even though they have the same color.
image of an extrusion machine from Wikimedia under the Creative Commons Attribution-Share Alike 4.0 International license.
The process called extrusion
Normally, what everyone thinks is that the name extrusion is related only to the metal working process but no, it is not. Extrusion according to the dictionary as paraphrased by me is
The process of making something by the application of force. -source
That definition is correct but still not clear to a layman, extrusion according to my understanding is a process of creating or making a piece by the use of a defined process of force application be it metal or food.
Take for instance that macaroni which is not yet hollow and smooth maybe like a cylindrical bar of macaroni on a lathe or CNC machine to perform drilling, turning, facing, boring. Would it not be ridiculous?
Considering the fact that there are several stands of macaroni in a pack, macaroni is not as hard as metal and the time it will take to process one will be so long in the manufacturing process. So, if this is considered before the production of macaroni started then we probably would not have macaroni today.
This means that the extrusion process is used to develop or create complex shapes of parts in metal, plastic or food which are not that hard in engineering the term is brittle.
Let us talk briefly about the brains behind it
From what I was able to gather about the history behind extrusion it is not so long but it started way back as the 17th century when one of the fathers of hydraulics made a patent of the extrusion process. He made pipes out of metals that were soft. Although the metal had to go through some process to become soft for it to pass through a die while using a hand driven plunger. The 18th century was the turn of lead pipes and he also followed the step of hydraulics. But the earliest name was squirting and was done by Thomas Burr. Copper and brass were next in line to be shaped using the extrusion process.
And today it is widely used in so many applications and even in food processing.
The extrusion process
The extrusion process is used in the processing of materials such as plastics, ceramics, metals, and food. It applies the use of some parts such as the die and a powerful press in form of hydraulics to force the raw material through the die (the shape of the die is responsible for the outcome). During an extrusion process, the die determines the product or the shape of the material to be produced or the outcome. Take for instance producing a trapezoid shape requires you having a die with the trapezoid shape cut inside of it.
The extrusion can occur in various ways some of which these materials have to be processed or just applied like that. Therefore, there are two basic methods of the extrusion process which are
- The hot extrusion process
- The cold extrusion process
The hot extrusion process
During the extrusion of some materials, let us take for instance the macaroni we have been talking about although there are various examples I could have referred you to but, the macaroni is common and so many people have seen it before.
The raw macaroni (in the sachet) when a certain force is applied on it would definitely break and might not give you the requires shape you want. This is because of the nature of these materials when it is cold. Now if we pick up a cooked macaroni and we decide to use a knife to cut out a triangle from it we find out that definitely, this is much easier and the macaroni would obey to your wish. This is because the property of the macaroni is not the same as when it is cold.
This analogy you just thought about can be thought as hot extrusion process, this means that the material has to be heated to a certain temperature which is above its recrystallization temperature (recrystallization temperature is simply a temperature below a material boiling point where the hardness and strength of the material has been reduced greatly). This means that the material is neither completely solid nor liquid.
This way, the force applied on ram of the hydraulic press would force the heated material through the die.Thereby, producing the shape of the die it is passed through. When it is allowed to cool then you would have produced a great shape of that material you need.
The cold extrusion processes
The cold extrusion process is done or carried out at room temperature i.e. below recrystallization temperature. The cold extrusion process requires more pressure being added than the hot extrusion, the material that is being reshaped using this process are usually soft and ductile.
The better part of this type of extrusion is that you do not have to heat any material, you are assured of better surface finish, better strength and lack of oxidation. Some of the materials that go through this process are lead, tin, aluminum these are just a few there are so many more.
Engineering application of the extrusion process
The extrusion process has so many applications in various fields you probably know about or cannot do without. For instance, the pipes you have in your homes are formed by a method of extrusion. Without them today I can’t possibly imagine what the world would feel like today.
The extrusion process is applied in the food processing industry which has to do with the shaping of food, snacks, cereals and used to make pellets of animal feed. Don’t be surprised I had the most feint idea too.
The extrusion process apart from the manufacturing industry is applied in the pharmaceutical industry to make drug carriers. They are also applied in the use of renewable energy to make biomass briquettes, biomass briquettes are applied and used as fuel for various uses. They consist of different waste munched together.
The extrusion process is a wide mechanical process which combines the use of force in hydraulic power to shape or get the best out of a material for other purposes.it is regarded as a metal working process but that would be absolutely wrong as I is used in plastics, ceramics and even in food processing to get the required shape of a material.
The extrusion process requires the use of a die which clearly determines the outcome in the shape produced or desired. The extrusion process can basically be divided in two ways which are the cold and hot extrusion process. The hot extrusion process requires one heating the material before applying the hydraulic press while passing them through a die.
Unlike the hot extrusion process, the cold extrusion requires more power in the hydraulic press as they are done at room temperature. Several things have been achieved using the extrusion process and this has saved a lot of resources and time instead of having to machine everything which is not even possible or reasonable as a manufacturing engineer.
The pharmaceutical industry, food processing, renewable energy, plastic, and ceramic industry have all benefited from the extrusion process developed by one of the kings of hydraulics. Share your thoughts about the extrusion process in the comment below.
Thanks for reading!
Knowledge is the beginning of all good things in life, it is a process and it is being improved upon here are the books and links I read.
- Textbook on Mechanics of Metal Extrusion Import by W Johnson
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