Drawing: what does it mean and what it is used for

Drawing is one of the primary processes in metalworking, essential for the production of a large number of components and finished products. This mechanical process, widely used in the manufacturing industry, enables the production of wires, tubes and other metal elements of various shapes and sizes. To ensure maximum efficiency and optimum results, it is essential to consider the use of protective coatings and lubricants during metal drawing: ATP Europe, in order to preserve the integrity of the material and improve the performance of this process, has developed Boron Nitride coatings. In this article we will learn more about metal drawing and why the use of protective coatings can be beneficial to a company!

What is metal drawing?

Metal drawing is a machining process used to reduce the diameter of a metal material, such as wire or tubing, through the application of controlled tensile forces. During drawing, the material is fed through a series of dies or dies with progressively smaller hole sizes. Through the application of compressive and tensile forces, the metal is plastically deformed, reducing its cross-sectional area and obtaining the desired dimensions.

The drawing process can be broken down into several stages, which include the initial extrusion of the metal through a larger-diameter die, followed by subsequent passes through increasingly smaller-diameter dies until the desired final size is achieved. During this process, the material undergoes significant deformation and may be subjected to heating to facilitate processing.

Metal drawing is widely used in many industries, such as automotive, aerospace, electronics and construction, for the production of a wide range of components and finished products. This process offers significant advantages, including the ability to achieve precise dimensional tolerances, a high quality surface finish and improvements in the mechanical properties of the machined material.

The drawing of metals is closely related to the ductility of the material. Ductility refers to the ability of a material to deform plastically without breaking under the application of external forces. During the drawing process, the metal material is subjected to intense tensile forces as it passes through the dies. As a result, greater ductility of the material allows for more uniform and controlled deformation, making it possible to effectively reduce the diameter of the material without cracking or defects occurring. Simply put, more ductile materials tend to be more suitable for drawing, as they allow for greater machinability and better results in terms of dimensional tolerances and surface finish of finished products.

How is drawing carried out and what is the supply chain?

As mentioned, drawing is a mechanical machining process involving the feeding of a metal material through a series of dies or dies with holes of progressively smaller size in order to reduce the diameter of the material and obtain the desired shape. During this process, the die plays a key role. But what is a die?

The die, (also known as a drawing die) is a cylindrical tool, usually made of steel or tungsten carbide, that has an internal hole with the desired shape of the end product. The die is made up of several sections, each with a slightly smaller diameter than the previous section, allowing the size of the processed material to be gradually reduced through the application of controlled tensile forces.

Metal drawing: how many types of drawing exist?

In the context of metalworking, there are different types of wire drawing that can be adopted depending on the specific requirements of the end product and the characteristics of the material to be processed.

  1. Cold drawing: This type of drawing is performed at or slightly above room temperature. It is mainly used for non-ferrous metal materials such as aluminium, copper and stainless steel. Cold drawing allows for tight dimensional tolerances and a high quality surface finish.
  2. Hot drawing: In contrast to cold drawing, hot drawing involves heating the metal material prior to the drawing process. This method is particularly suitable for ferrous metal materials, such as steel and iron, which become more ductile when heated. Hot drawing results in a greater diameter reduction and improves the mechanical properties of the material.
  3. Combined drawing: In some cases, cold and hot drawing can be combined to exploit the advantages of both methods. For example, an initial hot drawing can be performed followed by cold drawing to achieve more precise dimensions and a better surface finish.
  4. Deep drawing: This type of drawing involves significantly reducing the diameter of the material, often more than 50 per cent of the initial diameter. It is used to produce components with large diameter reductions, such as needles, pen tips and other products that require extremely small dimensions.
  5. Continuous flow drawing: In this method, the metal material is continuously fed through the die without interruption. This process is suitable for the mass production of products with fixed lengths, such as wire or pipes.

What is the difference between drawing and extrusion?

Metal drawing and metal extrusion are both machining processes used for plastic deformation of metals, but they differ in the way force is applied and the results obtained.

Drawing involves the passage of a metal material through a series of dies or dies with progressively smaller holes. During this process, the material is compressed and guided through the dies by the application of controlled tensile forces and ultimately results in a reduction in the diameter of the material and a change in its shape.

Extrusion, on the other hand, involves the insertion of a metal material through a die or die with a specific shape, under the action of high pressure. During extrusion, the material is pushed through the die by a screw or piston, generating pressure that causes it to flow through the die and assume its shape. The end result of the extrusion is the formation of a product with a constant cross-section and a shape determined by the geometry of the die.

Metal drawing and lubrication: boron nitride coatings

In the context of metal drawing, the efficiency of machining processes largely depends on the correct lubrication of dies and material. In this context, ATP Europe’s boron nitride protective and lubricating coatings prove essential to improve the efficiency and quality of finished products.

Boron nitride is a material with exceptional properties of abrasion, corrosion and friction resistance, making it particularly suitable as a lubricant coating in metal drawing operations, enabling higher feed rates and reducing tool wear. This translates into higher productivity and longer die life, while reducing maintenance costs. In addition, boron nitride coatings improve the surface finish of the processed material, reducing the adhesion of metal debris and improving the quality of the finished product. This is especially important for applications requiring tight dimensional tolerances and a smooth surface.

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