Measuring wire drawing dies

In this two-part blog series, we’re going to examine wire drawing dies in some detail. In this, part 1, we’ll look at measuring wire drawing dies, why accuracy is so important, and what’s the best way to go about measuring them. In the part 2, we’ll address the question of why they need to be measured in the first place.

The central step in the manufacturing of wires is obviously the wire drawing process. In simple terms, it involves pulling the raw material from which the wire is made through a series of progressively smaller dies to achieve, ultimately, a target diameter (and, sometimes, shape).

It follows logically from this that for the result, the wire itself, to be of the necessary standard and specification, the drawing dies used must always be fit-for-purpose too. As such, measuring wire drawing dies (to ensure their accuracy) is critical. An inaccurate die leads to an unusable wire – creating waste and incurring costs.

What are we measuring?

When measuring wire drawing dies, the process is not as simple or straightforward as just measuring an object in its totality. There are a lot of specific considerations that must be accounted for, given the die’s shape and how that works to ensure the quality and precision of the drawn wire. The key parameters for measurement (which also give insight into the die itself) are:

  • Diameter: The diameter of the die aperture is what determines the final diameter of the drawn wire, so there is no margin for error. The aperture must also be on specification and manufacturers must be vigilant as dies can erode due to wear and tear over time.
  • Angle: The angle of the die entrance, called the approach angle, is where the wire enters the die. This area affects both the downstream drawing process and the quality of the drawn wire at the end of the process. Similarly, the reduction angle also needs to be considered, as this determines the resulting output. At the same time, the lubricants used, the speed of the process and the hardness of the material are also factors to consider when looking at the angle of the drawing die. Similarly, the process will generate heat, so the correct choice of die for the process in question another consideration.
  • Bearing length: The length of the die bearing is variable according to the manufacturing process and needs to be correctly understood to ensure quality. Again, drawing speed, lubrication and material type are factors to consider.
  • Wear: Dies must be regularly inspected for wear to deliver consistent wire diameter and quality. Wear can lead to dies breaking during manufacturing, but it can also result in poorly manufactured products.
  • Polishing: Surface finish of the die is vital for reducing friction during the drawing process because it impacts wire quality. The surface roughness of a die can be measured too, and addressed if it is found to be problematic. The polish is negatively impacted by wear.
  • Material: The material composition and hardness of a die affect its durability and performance.
  • Roundness (Ovality): The ovality of the die aperture ensures uniform drawing and consistent wire diameter. It is also an indicator of die wear.
  • Shaped dies. Dies can also have other shapes for producing, for example, square or triangular.
  • Alignment: Proper alignment of the die within the drawing machine to which it is sited is vital to achieving accurate wire dimensions and preventing premature wear. Similarly, the alignment of the bearing cylinder with the casing that surrounds it is also highly relevant and should be measured.

In short, precisely measuring wire drawing dies is multi-faceted, and involves considering parameters related to dimensions, surface quality, wear, and alignment all of which combine to ensure a dies optimal performance and, by extension, the quality of the drawn wire.

What do we measure with?

While there are many ways in which drawing dies can be measured, camera-based measurement systems offer many advantages when compared to other methods. Why?

First and foremost, camera-based systems do not require physical contact with the die surface, which minimizes the risk of damage or deformation in the measuring process. When dies are delicate or highly polished – as is often the case – contact measurement methods can affect surface integrity. Solutions that use contact methods measure indirectly, as they are always measuring the object that is in contact with the die, rather than the die itself.

Second, camera-based systems provide high-resolution images, which enable precise measurement of dimensions such as diameter, length, ovality, and bearing angle to be achieved with ease.

Without a high level of accuracy, tight tolerances cannot be met, and quality standards can’t be assured. Furthermore, camera-based systems are also able to capture measurements more quickly and efficiently when compared to the alternative manual measurement approaches. This streamlines the inspection process and reduces production time, critical advantages in age where costs need to be managed as closely as possible.

Objectivity. The measurement results need to be repeatable and comparable – and not dependent on the person who performs the measurement, or the equipment used. In other words, we need tools that enable anyone, anywhere in the world to take the same die, using the same tool and obtain comparable results.

The systems can also often be integrated into automated inspection setups, allowing for continuous monitoring and measurement of wire drawing dies without human intervention. This improves workflow efficiency and reduces labor costs.

Another advantage of Camera-based systems is that they can measure multiple parameters of wire drawing dies in a single tool, including diameter, ovality, bearing length, and reduction cone.

Plus, they also have advantages in the increasingly important area of data. Camera-based systems can include software for image processing and analysis, enabling advanced data visualization, statistical analysis, and documentation of measurement results. This makes for improved quality control as well as delivering insights that are helpful for process optimization and troubleshooting.

Summarizing the benefits

To summarize, camera-based measurement systems offer a combination of accuracy, speed, versatility, and automation that has, for many manufacturers of drawing dies and wire, made them the best option for inspecting and measuring wire drawing dies and by extension ensuring the quality and precision of the drawn wire.

Conoptica is the market leader for measurement equipment in the wire & cable industry and has been providing high tech camera-based measurement solutions since 1993. We provide the ability to deliver consistent, objective results for all kinds of drawing dies.

We make sure that the metal working industry has access to key quantitative data about their products and tools.