WHY
In an industrial forming operation, the friction between tool and workpiece, or workpiece and die, determines the quality and efficiency of forming. Too high friction can cause wrinkles or tears, resulting in scrap. Forming lubricants appear to be sensitive to temperature, so the optimal forming conditions may vary with increasing temperature, as the machines warm up.
Forming in industry involves a deformation of the workpiece and a limited sliding against tool and die. To evaluate the change in friction control by forming lubricants, we perform a simplified simulation on the Falex Multispecimen machine that includes a forming component in the workpiece (sheet) to create conditions close to real mechanisms.
HOW
We are using a special test adapter, designed for the Falex Multispecimen machine, that allows deformation of a sheet during a slow sliding operation. This means pressing a ball against a sheet, but allowing deformation of this sheet while increasing pressure on the contact.
As the sheet can be heated by the Multispecimen table heater, tests can be done at different operational setpoints.
MOVIE : https://youtu.be/4_bVBKt2LHc
RESULT
we can simulate the simultaneous sliding of a tool (ball) over a workpiece (sheet) and the deformation of the workpiece, and measure the changes in friction and deformation forces for a range of lubricants and at different operational temperatures.
Typical results :
- The entire "force vs. sliding time curve" shows the resistance force against sliding, while deformation takes place. The picked up force includes both deformation of the sheet, and pure sliding friction.
The repeatability of the test is illustrated.
- The sensitivity of the resistance force with temperature shows that friction increases with increasing temperature (as was also observed in more extensive strip drawing tests).
- The method allows a fast and cost efficient screening of different lubricants, at different temperatures and sliding speeds.
- It helps to select the right lubricant for the right conditions (more or less temperature sensitivity, speed sensitivity, etc).
- for more information, you can also check out our article :
E. P. Georgiou, D. Drees, T. Van der Donck, J. Hazrati, M. Veldhuis, B. Aha, M. Anderson & J.-P. Celis (2022)
A New Test Method to Simulate Deep Drawing Phenomena on the Lab Scale, Tribology Transactions, 65:5, 892-900,
DOI: 10.1080/10402004.2022.2100852