OBRABOTKAMETALLOV TECHNOLOGY Vol. 26 No. 4 2024 Step 7. To calculate the grey relational grade by mean value of GRCs: grey relational grade is an average sum of the grey relational coeffi cient, which is defi ned as follows: ( ) 0 1 0( ) ( , , ) 1 . m i i i x x x k x k m = γ( ) = γ ∑ Step 8. To determine the optimal parameters. Step 9. To predict the grey relational grade when setting optimal parameters. Results and Discussion The sliding wear study of PLA material on SS 316 steel disc was carried out using a pin-on-disc friction machine. In this machine, a seesaw arrangement was made by attaching a rod to transfer the normal load to the pin by attaching weights to the other end. LVDT sensor was used to detect the change in displacement due to material wear. The rotation speed of the disk was varied by selecting an appropriate track diameter. The test was carried out on a 4 kilometer track distance (approx. 18 to 22 minutes). A control panel was attached to the machine, as well as a computer that displayed the speed, friction force andwear for the relevant processing parameters. Windcom software was used to show the variation in wear and friction force with respect to test time and track distance of 5 km. Figure 4 shows the wear track image of PO1, PO2 and PO3 formed on the SS 316 disc. The pins were manufactured using the FDM technology with printing orientations of 0°, 45° and 90°. Hereinafter, the pins manufactured with a printing orientation angle of 0°, 45° and 90° will be referred to as PO1, PO2 and PO3 respectively. The printing orientation of the pins in the form of a CAD model and in real printing is shown in Fig. 5, a and b respectively. The experiments were performed according to DOE and the sliding wear was recorded for diff erent values of normal load and sliding velocity. The experimental results along with the wear track images for all tests are summarized in Tables 2 and 3. All required environmental conditions were constant for all experimental tests. A mathematical equation based on the power law was used to predict the wear by considering the normal load (N) and speed (rpm) and is Fig. 4. Image of wear tracks of FDM printed pins on a SS 316 stainless steel disc a b Fig. 5. 3D printing orientation: a – CAD model; b – printed pins
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