The Creation of an Extrusion Die

Plastic extrusion has been used to create many plastic products since the early 1900s and there have been many advancements in extrusion dies throughout the years to create a wide variety of shapes and profiles.

Extrusion dies are circular steel disks which contain one or more openings to create a desired profile/shape. They are an essential piece of equipment when carrying out extrusion work. Typically, extrusion dies are made from H13 steel and heat-treated to ensure they can withstand intense pressure and heat during the extrusion process as the material is pushed through the die and extracted.

So, how are extrusion dies created, and what types are there?

Types of Extrusion Dies

There are many different types of extrusion dies that you need to be aware of. These are all created for specific extrusion needs and are designed with a specific cavity that matches the desired shape of the product.

Solid Dies

A solid die creates a final shape that has no enclosed voids or openings.  For example, solid bars, angles, channels, rods and beams. A solid die is also usually less expensive to manufacture when compared to other die types as there are less components included in the machine.

There are many elements that go into the creation of a solid die:

Feeder Plate – this controls the metal flow through the die.

Die Plate – this forms the shape of the material.

Backer Plate – this supports the tongue of the die to prevent collapse or distortion of the material.

Bolster – This supports the extrusion load transmitted from the die and backer.

Hollow Dies

A hollow die produces shapes with one or more voids or a complex profile with many detailed voids. For example, a simple rectangular tube or a complex multi void t-slot. Hollow dies usually have a higher cost due to extra components and can get more expensive when more voids are included.

There are many elements that make a hollow die, including:

Mandrel – This is located inside the die and has two or more port holes that generate the internal features of the shape and control the flow of metal during the extrusion process.

Die Cap – This is a multi-piece die that makes the shape.

Bolster – This supports the extrusion loads which are transmitted from the die cap and mandrel.

Semi-Hollow Dies

A semi-hollow die extrudes a shape that is nearly hollow and has a void or voids. They include the same elements as a hollow die, without the elements to make a complete void.

The main element determining the difference between a hollow and semi-hollow die is the tongue ratio, defined by the ratio of the area of the void to the size of the gap where the tongue is connected to the main body of the die. For semi-hollow dies, the tongue ratio is larger than a solid die. This, therefore, creates more complexity when manufactured, which creates a higher cost.

These extrusion dies are used in a wide range of industries, from automotive, construction, hospitality, transportation, agriculture and industrial, as they help to create a range of shapes and profiles for a wide variety of applications.

Here at Rayda, we create high-quality bespoke products from plastic extrusion. Contact us today to talk about your plastic extrusion needs or learn how we can help.