A Comprehensive Guide to the Process & Importance of Extrusion Tool Making

The Extrusion Process

Before delving into tool making, it’s useful to review the extrusion process itself. In extrusion, materials such as aluminium and plastics are heated and forced through a shaped die under high pressure. The die itself is an essential part of the extrusion tool, determining the shape and profile of the extruded product.

The material emerges from the die in a continuous length, which can be cut or processed further. The extrusion process offers several advantages, including:

• High precision in product dimensions
• Continuous production of uniform, cross-section profiles
• Versatility to work with various materials

Given the crucial role the extrusion tools play, precision in their design and manufacture is key to achieving desired results.

What is Extrusion Tool Making?

Extrusion tool making refers to the design, development, and manufacturing of tools used in the extrusion process. Typically made from high-quality, durable materials that can withstand the extreme forces and temperatures during the extrusion process, these tools typically include:

The Die is responsible for the shape of the final product as it contains the profile through which the material is extruded.

A Mandrel is used in hollow profile extrusion. By supporting the material, it ensures uniform thickness and shape in hollow sections.

Bolsters and backers provide structural support to the die, especially under high-pressure conditions, ensuring uniform flow and reducing wear.

The Extrusion Tool Making Process

Tool making is a highly specialised craft that requires precision engineering and a deep understanding of the extrusion process with the following key steps:

Profile Design

The process begins with the design of the desired product profile. This can range from simple shapes like rods and tubes to complex, intricate profiles used in industries such as the automotive and aerospace industries.

Designers use CAD (Computer-Aided Design) software to create detailed blueprints that can then be used in tool development.

Material Selection

Choosing the right material for the extrusion tool is essential. Tool makers use materials such as tool steel (often alloyed with chromium, vanadium or molybdenum) for its high resistance and strength properties. For some plastic extrusion processes, hardened stainless steel or nickel based alloys might be used.

Tool Machining & Fabrication

Once the design is finalised, the tool is manufactured using advanced machining techniques such as CNC (Computer Numerical Control), milling and turning. The precision of these machines ensures that the die shape and surface are accurate to the micron level.

Heat Treatment & Surface

After machining, the tool undergoes heat treatment to improve hardness and durability. High temperatures are applied to increase wear resistance and to reduce any likelihood of deformation under pressure. The final surface finish of the tool is also important, as ensures a smooth flow of material through the die and minimises friction from happening.

Testing & Calibration

Before the tool can be put into production, it must be tested to ensure that it meets the required specifications. This involves running a series of test extrusions and making any necessary adjustments to the tool. We do this as proper calibration is critical for product uniformity and consistency.

Tool Making Challenges

Extrusion tool making is a well-established process, and yet, it can provide challenges that need to be taken into consideration, such as:

• Wear & tear – extrusion tools experience significant stress from both the high pressure and heat of the process, causing them to wear down over time. Tool makers take this into account during the tool making process by using high-durability materials and by designing tools that can be easily maintained. This also ensures that they are as cost effective as possible.
• Complex profiles – creating complex profiles with tight tolerances requires a deep understanding of material flow and tool design. Even a small error in the die can lead to defects in the final product. Yet another reason we only use experienced tool makers who we have established relationships with.
• Heat control – managing the heat generated during extrusion is crucial. This is because excessive heat can cause the material to deform or damage the tool; at BWC Profiles we take this into consideration by applying proper heat treatment and cooling systems as they help prolong the life of the tool (which keeps further costs down too).

Advances in Extrusion Tool Making

There have been exciting advancements in technology in recent years that are significantly improving the tool making process, including:

• Simulation software – modern CAD (computer aided design) and simulation tool allow engineers to predict how materials will flow through the die before it is manufactured, reducing the risk of costly trials and errors.
• Additive manufacturing (3D Printing) – for certain applications, 3D printing can create extrusion tools with highly complex geometries that wouldn’t be possible to achieve via traditional machining methods.
• Advanced coatings – tools can now be coated with advanced materials that help reduce friction and increase wear resistance, improving their longevity and performance.
  
  

In conclusion, it is clear that tool making is a critical step in the manufacturing process; with precision, durability, and innovation at the heart of this specialised craft, ensuring that products are made to the highest standard.