Wire drawing: assuring accuracy of your drawing dies

In industrial scale wire production, hundreds if not thousands of drawing dies can be in use continually and simultaneously. For precision manufacturing, accuracy is key. So, it’s worth taking a closer look at factors that can reduce accuracy and how you can maintain quality through accurate measurement of your drawing dies, as we’ll do in this blog.

Industrial wire drawing

First, let’s revisit where dies fit into the manufacturing picture. In commercial wire drawing environments, there are different basic modes of processing and equipment into which the die fits. The three most common are benches, blocks, and multi-die machines. Benches are the simplest of these, limiting the length of the wire to the length of the bench and generally being deployed for smaller production runs.  In heavier industrial situations, blocks come into play, usually when the wire is either robust or small enough in diameter to allow it to be coiled around a capstan as it passes between a sequence of dies, each narrowing it (and elongating it) further towards its desired end size. Block drawing speeds average in the range of 100 to 200m/minute.

The height of commercial productivity is the multiple die machine, now widely deployed.  Somewhat similar in principle to the block, these operate at higher speeds with capstans of varying diameters and different velocities that enable different pulling rates at different parts of the sequence (to compensate for the changes in the wires length and diameter as it passes down the sequence. In simple terms, the drawing speed increases as the wire lengthens). Depending on the wire’s raw material, drawing speeds here can reach up to 600m/minute, with 200m/minute being common. More modern machines can draw many wires in parallel, obviously increasing the number of dies (and capstans) deployed. In short, they’re complicated beasts!

Understanding the process

As we’ve noted, in industrial settings (whether block or multi-die) hundreds of dies will operate alongside or in sequence with each other. Die quality is extremely important. Along with other factors such as lubrication, raw materials, temperature, and drawing speed, it contributes directly to the success or failure of the entire wire drawing process. If the die is in some way out of specification, then the wires produced won’t be fit for purpose. So, what makes an effective die? If you’re drawing wire commercially, what should you be looking for?

The key word is accuracy: that’s the dimension that determines whether a die is usable. Dies must be measured with high accuracy to ensure the output wire is of the exact specification required (which obviously determines whether the end-product is fit for purpose).

Die geometry and size can’t be taken for granted. Specifications (such as diameter, ovality, bearing length, and reduction cone angle) must be given with proper accuracy.  Imperfections in the dies themselves can represent a serious problem that negatively impacts production, quality assurance and product reliability. So, ensuring that die sets are of the required quality is essential. In commercial settings, if quality isn’t assured, big problems can quickly follow.

The monitoring required to ensure die quality is maintained needs to be done on an ongoing or at least regular basis, not least because wire drawing, a process which involves the generation of friction and thus heat as the wire is pulled, can cause degradation (how much and how rapidly is related to both the properties of the underlying metal and the drawing speed as well as other factors). The effects of friction and heat are offset as far as possible by cooling or lubricating the die, but they cannot always be eliminated completely.

For now, it’s enough to say that robust as they may be, commercial manufacturers must cope with the inevitably of their dies deforming over time.  Think about the machinery we described earlier in this blog; there are a lot of moving parts and a fair degree of complexity.

Getting it right

Achieving accuracy means ensuring that your drawing dies are maintained to the highest standards. Incorrect dimensions impact performance and the quality of output so failure to ensure that dies maintain the correct dimensions can lead to:

  • Increased numbers of production halts 
  • Reduced drawing speed
  • Reduced wire quality
  • Higher number of wire breaks
  • Reduced die life and quality
  • Unnecessary costs when unusable wire is formed wasting the raw materials. 

Wear and tear – a perfectly natural phenomenon – will impact accuracy by changing even by a small degree the performance of the die. The more accurate your tools and processes are for wire production, the better your end results and in the process, the more you’ll optimize your return on investment.

While not all wire needs to be produced to exacting standards (fence wire, for instance, is one example) it’s nevertheless generally true that if you can accurately measure your dies, you can replace them before quality declines and so preserve performance.  Measurement is a critical step.

When dies are compromised, either by incorrect manufacture, wear and tear, or for other reasons, the dies involved must be taken out of service for repair or replacement. While to some extent this can’t be avoided altogether, by using dies with the correct size and geometry, wear resistance and thus die life will be improved. That means measuring and thus assuring the performance of your die sets is essential to delivering the highest quality manufacturing outcomes, including:

  • Reduced die cost.
  • Increased die life.
  • Fewer “bad” dies going to the drawing machines.
  • Reducing the number of you need to keep in stock.

When you are producing at scale, with thousands of dies in use each day, checking for compliance with the required output specification is essential – as just one error can disrupt your production. And you need to be able to achieve this quickly and with the requisite scale to meet your needs.

About Conoptica

A leading source of high accuracy measurement systems for drawing dies is Conoptica, which offers a variety of measurement systems suitable for dies of different sizes. They enable the accurate measurement of dies, so that you can track consistency and take appropriate actions – avoiding excessive quality deterioration and enabling better management of your die stocks.

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

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