The New Condition Monitoring for Wire Drawing

Before a wire ring is drawn, the quality factors in the forming process must be in the right proportion to each other. Only a well-balanced ratio of cross-section reduction, drawing speed and lubrication enables efficient process stability and highest quality. Even with a geometric determination of the drawing die, the design and dimension of the coefficient of friction (coefficient of friction) is estimated or assumed as a whole according to empirical values. In practice, the most economical drawing speed is not determined directly, but tested. The QASS wire drawing condition monitoring provides a remedy here.

The partly kilometre long product “wire” poses a hurdle for quality testing. With the Optimizer4D measuring system from QASS, an automatic quality inspection is finally available that monitors the forming process non-destructively and is robust against oils and dusts.

“How did the wire run?” – This is probably the most frequently asked question to an experienced wire drawer. This is exactly where QASS comes in. As the only company worldwide, we measure and factorize the entire course of the tribological interaction between wire and drawing die. The direct relationship during the forming process can be read live, i.e. in real time, on the production screen. The output here is in the form of a 2D diagram: %] Deviation over [t] time.

Our wire drawing condition monitoring enables a wire puller to determine the optimum or most economical drawing speed with the best possible quality.

Almost every multiple wire drawing machine can be equipped. The sensor, about the size of a table tennis table, fits into any drawing box.

Move the white slider in the image.

Different drawing speeds provide different HFIM signals. If the quality of the product deteriorates, easily detectable anomalies occur in the HFIM image. The QASS measuring system can optimize your processes and determine the most economical and optimal drawing speed.

On the left you can see the HFIM image of a wire drawing process with a drawing speed of 6 meters per second. It documents a consistently high wire quality. The picture on the right shows a pulling speed of 12 meters per second.

Fig. left: Determination of the optimal drawing speed. Speed increase from 8 m/s to 9 m/s. Working card 8 m/s (+/- 1 m/s). Material: cold heading steel.

Result: Higher drawing speed with constant quality. An increase from 8 m/s to 9 m/s is recommended. Friction conditions and wetting degree show equally stable conditions.

Fig. left: Determination of the optimal drawing speed. Specification of the work order: 11 m/s (+/-1 m/s). In the left range of 12 m/s mixed friction and static friction occurs. In the right-hand area, pulling is performed at a speed of 11 m/s. Only mixed friction occurs here.

Result after the analysis: The optimum drawing speed with constant quality is 11.8 m/s.

A brand-new die emits different HFIM signals than a worn one. Optimizer4D detects in real time when the determined tolerance limits are exceeded. For this purpose, the measuring system is given information about the die card and the production order. Optimizer4D checks the quality of the last two static drawing tools of a multiple wire drawing machine – afterwards an automatic quality control of your process is guaranteed. This ensures, among other things, that the quality of the drawing tool is checked. Right picture: A lubricant film breakage detected by QASS on a multiple wire drawing machine.

Anyone who produces wire of a particularly high quality knows that the fault tolerances are very low. Optimizer4D helps to find out the optimal drawing speed. At the same time, the system detects if lubricant loss is imminent or has already occurred – if desired, Optimizer4D can stop the system. Temporary mechanical damage can be seen in the HFIM image, such as the wire break. Optimizer4D not only monitors the production, but also documents the results. The software indicates to what extent the quality deviates from the desired standard. QASS provides the following features:

• Automated monitoring and documentation of all wire draws;
• Real-time visualization of the running process, e.g. in a 3D landscape;
• Deviations are detected and documented immediately;
• Error logging, even of small sections with errors;
• Proof of quality with ring number and time stamp;
• A graph shows the quality of each coil, each ring. If desired, the graph can be output as a document.

What makes the implementation so uncomplicated?

• No interruption of the running process
• Easy sensor installation
• Only one employee training session necessary
• Consulting and installation by QASS on site
• Practical Performance Tools for Machine Operators
• The QASS Service Promise

There are many measuring instruments for acoustic quality control, but only QASS analyzes frequencies in addition to signal strength. Only the selective frequency display opens up a differentiated view of the process.

Certain frequency ranges carry different information than others – in QASS mode, it is easy to mask out those ranges which, for example, contain interference or signals from irrelevant sources. In addition, the QASS system is less sensitive to dirt such as optical-based processes.

Acoustic testing is also less susceptible to misinterpretation of the surface. Even internal damage can be detected if it generates higher emissions during plastic forming from die to die than an undamaged wire.