Extrusion

• The plastic enters the feed part where the plastic is pushed through a special screw all the way to the die. The shape of the screw changes diameter from beginning to end, exposing it to a lot of heat and pressure resulting in a fully molten plastic when it reaches the end of the screw. From there it enters the die - you can use different shapes for different products.

Blow molding

• You can also use techniques like blow-molding, where you take the output of the extruder when it is still warm and blow it into shape with the help of compressed air and a mold.

Injection molding

• For this process, plastic is injected into a mold, solidified and then cooled down. When it’s cooled, it keeps the shape of the mold. You can make a lot of products with injection molding, for example Lego pieces, toothbrushes, CD cases, or cutlery. 

Thermomoulding

• Sheets are heated to a pliable temperature, formed into a specific shape and then cooled and trimmed. This process is often used to create disposable cups, containers, lids, trays - a lot of thin-walled plastic items that are used in the food, medical and general retail industries.

Rotational molding

• This process is used to create low-quantity large plastic items. Plastic pellets are placed in a mold, and are molten with heat while heated evenly. The process is quite flexible as the mold doesn’t have to withstand high pressure. It’s very labor intensive though and takes a significant amount of time.

Additive manufacturing (or 3D printing)

• This is a relatively new production process. Here, multiple 2D layers make up a 3D shape and the benefit is that you don’t need a mold so you can change the design as much as you want. However this process is slow and currently it is rather difficult to make 3D printing filament from household waste.