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Traction curve plots friction vs. slide-roll-ratio (SRR) at constant load, temperature and entrainment speed - conditions representative of EHL contacts. The modular traction tribometer (MTT) provides a versatile interface to execute a traction protocol i.e., a linear variation of SRR under constant entrainment velocity while simultaneously measuring friction and electrical contact resistance. The initial and final SRR can be varied between -1 and +1 with a maximum entrainment velocity upto 2 m/sec. The advanced software calculates and executes the ball and disc speed profiles based on the input parameters.
LabIQ is a powerful and easy to use software interface that guides users through 5 steps to set up a test and obtain traction data. The sequence starts with material definition - defining load profile - defining motion profile -configuring temperature and additional sensors - and finally executing the test.
On the LabIQ Home screen, enter the test and operator details: Operator Name, Operator ID, File Name, Sample ID and Notes. These parameters are tagged with the raw data to ensure traceability.
Once all the information is uploaded, click on Select Load Head
Force sensors are automatically identifed as per the instrument configuration. DecaForce (2 to 200 N) is typically used and the default option. Furthermore, the loading profile can be set as Constant, Stepped or Ramp. and the operator can program the values, together with the trip limits of normal load and friction force which work as emergency threshold values at which the test automatically stops.
A load of 50 N on a 20 mm diamater steel ball and steel disc results in a contact stress of 1 GPa.
Several Motion Modules (red area) can be configured on MTT; click on Traction to set up a test protocol.
The Motion settings (green area) offer flexibility to execute tests with a variable wear track diameter on the lower disc. Furthermore, users can select Constant, Stepped or Ramp speed profiles and program the values. For Traction curve, select Speed Ramp and variable SRR, Enter Initial and Final SRR and fixed Entrainment velocity values..
Typical input parameters are SRR-ini of -0.5, SRR-fin of +0.5 and entrainment speed of either 1 m/sec or 2 m/sec
Click on Set up Environment.
Lubricant cup heating can be enabled under Environmental conditions (red area) with temperature monitoring. Additional sensors such as electrical contact resistance can be chosen to actively record signals during the traction test. The ECR (Electrical Contact Resistance) module during the sliding is the signal that gives an insight on film thickness variation during the test.
Click setup to Execute Test
Set the test duration, typically 5 mins for a Traction test. All parameters are monitored across four separate windows. The raw data is saved as a simple text file with appropriate headers and can be exported for further analysis.
In the post analysis menu, multiple files can be compared. Furthermore, traction can be plotted vs SRR to quickly determine the limiting values.
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