PSI - Issue 39

M.A. Sánchez Miranda et al. / Procedia Structural Integrity 39 (2022) 161–172 Author name / Structural Integrity Procedia 00 (2019) 000–000

164

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The friction stir welding parameters for the dissimilar welding ABS-PP were as shown in Table 3. The first column corresponding the number of tests, the second one the rotational speed, the third the advanced speed, followed by penetration speed, model of pin and finally contact or non-contact between the shoulder of pin and the welding materials. The tilting angle for all tests was 0 degrees.

Table 3. Parameters used in friction stir welding for dissimilar polymers ABS-PP.

Penetration Speed (mm/min)

Pin Profile

Contact pin shoulder/ Material

FSW Test

Rotational speed (rpm)

Advanced speed (mm/min)

1 2 3 4 5 6 7 8 9

1060 1060 1060 1060 1060 1060 1060 2000 2000 2000 3000 2000 2000 2000

30 15 15 10

20 10 10 10

Cylinder Cylinder Cylinder Cylinder Cylinder Cylinder Cylinder Cylinder Cylinder Cylinder Cylinder Cylinder Cylinder Cylinder

No No Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes Yes

5 5 3

5 5 5 5 5

1.5

2.5

3

10 11 12 13 14

1.5

3 5 3

2.5 2.5 2.5 2.5

1.5

The two first tests in Table 3 yielded no bonding of the two polymeric material; the third and fourth tests induced an imperfect bonding with the corresponding welding parameters. The fifth test seems to improve the joining of the dissimilar materials; even if the tunnel defect is observed in the first 5 cm from the beginning of the welding process, as shown in Figure 3. The tunnel defect is often associated with the flow-out of material, particularly in the retreating side.

Figure 3. Joining of ABS-PP polymers using the parameters of test 5 in Table 3. Tunnel defect observed at the beginning of joining (5 cm length from the initial point). . A possible explanation of this behavior is related to the initial temperature of polymers, and the deficient flow of material in the retraining side. Some references point out that the increase of initial temperature of FSW joining polymers improves the joining process [ 21, 22 ] ; this would be related to homogeneous heat distribution approaching the fusion point, and the improvement of mixing process. In test 7 of Table 3, the advanced velocity is reduced to 3 mm/min, reducing the tunnel defect at the beginning of welding to 3 cm approximately. In tests 8 of the same table, the rotating speed was increased, together with the reduction of advanced speed and penetration speed; this time, the tunnel defect was reduced to 1 cm from the beginning of welding. The combination of welding parameters shown in test 9 of Table 3, generates the FSW of ABS PP without tunnel defect, as shown in Figure 4.