What is Extrusion?

Mary Elizabeth
Mary Elizabeth

Extrusion, from the Latin past participle extrudere meaning “to thrust out,” refers both to the process in which material is forced through a die or series of dies in order to shape it as well as to the product of that operation. The process is used in the home and in manufacturing. The shapes most often produced in this way include round objects like tubes, rods, and pipes, rectangular objects like solid and hollow bars, and plates. The term also refers to the outpouring of lava from a volcano.

Ropes of clay are extruded through a tabletop grinder.
Ropes of clay are extruded through a tabletop grinder.

In the home, the most familiar example of extrusion may be the pastry bag. Used to form cookies and to frost cakes, the pastry bag extrudes icing or dough through a tip that shapes the output. This is done in short bursts to produce a set of identical items quickly. Kitchen equipment that makes pasta or sausage may also feature an extruder that shapes the finished product. A very popular extruder toy is sold with modeling compound, in which a user selects a die and slides it across the front of the machine, inserts the soft material, and presses the handle to produce either long or short pieces of clay in the shape desired.

The outpouring of lava from a volcano may be referred to as extrusion.
The outpouring of lava from a volcano may be referred to as extrusion.

In manufacturing, extrusion is used with a variety of materials, including metal, plastic, ceramics, and food. Different materials undergo this process to make different types of products. Copper is extruded to make pipes for plumbing, while aluminum is used to make things like window frames, tracks, and railings. Steel is extruded into tracks or rods, and some titanium aircraft parts are produced this way. Plastic extrusion results in an array of shapes, including cylindrical tubes, pipes, and rods, rails, and very thin rectangular surfaces that are characterized as sheets or films.

Food manufacturing uses extrusion in ways that go beyond what is possible in the standard home kitchen. Cheese curls and other snacks, pastas, cereals, and nutritional bars all are made with this process, as are a number of pet foods. In fact, extruded foods is a food science specialty, and scientists who have training and experience in this particular realm of food manufacturing oversee these processes. There is debate over whether making food this way, in at least some cases, reduces the nutritional quality of the item.

Plastic extrusion is used to make wire insulation.
Plastic extrusion is used to make wire insulation.
Mary Elizabeth
Mary Elizabeth

Mary Elizabeth is passionate about reading, writing, and research, and has a penchant for correcting misinformation on the Internet. In addition to contributing articles to wiseGEEK about art, literature, and music, Mary Elizabeth is a teacher, composer, and author. She has a B.A. from the University of Chicago’s writing program and an M.A. from the University of Vermont, and she has written books, study guides, and teacher materials on language and literature, as well as music composition content for Sibelius Software.

You might also Like

Readers Also Love

Discussion Comments


I loved playing with modeling clay when I was a kid. I have found the best clay to use is the kind you make yourself. It is much more pliable and doesn't dry out as fast.

There are so many fun and creative things you can do with this clay. We have several 'tools' that make this a fun experience. One of them is a tube where you can stick in the clay and it comes out the end looking like hair. This is a great way to add embellishments to the people and animals we create.


Cheese curls are one of my favorite snacks. They also make these in the form of a ball, but for some reason I love the traditional cheese curl design. What kid doesn't love to pick up a cheese curl and snack on it. Even though they are messy, they sure taste good! I never thought about the process that was involved in making them, but they have been a success for many years.

Thinking about using the extrusion process in the kitchen reminds me of the butter cookies my grandma used to make every Christmas.

She had a tube where she would insert the dough. There were different attachments you could put on the end of the tube for whatever shape you wanted to make. You could make stars or different flower shapes.

She would add food coloring to the dough and make these cookies in different shapes and colors. These cookies are still some of my favorites. They are small, sweet and melt in your mouth. The extrusion process made it easy to make these cookies, yet it was creative at the same time.


When you think about it, there are a lot of things that you use the extrusion process for in the kitchen. I have a friend who owns her own bakery and she uses products like this all the time to squeeze out frosting to decorate all of her different pastries.

When I am frosting cookies at home, I make up my own pastry bag using a zip-loc bag. I spoon some frosting in the bag and cut off one end with the scissors. This makes a nice tip to decorate with, and the best part is the clean-up process. All I have to do is throw the bag away!

Post your comments
Forgot password?