The Effect of Welding Process Parameters on the nilon-6 Plate Friction Stir Welded Joint

Abstract

Nylon-6 is one of the most extensively used engineering thermoplastics. Due to its durability, reduced weight, low coefficient of friction, and abrasion resistance, this polymer is an excellent substitute for various materials, including metals and rubber. Despite being those, nylon-6 materials are joined together utilizing multiple welding processes. The current work examined the viability of the friction stir welding (FSW) method on nylon 6 plates that were 4 mm thick to investigate the effect of tool diameter ratio and feed rate on nylon-6 sheets with the FSW method on the tensile properties of the joints. The 4 mm thickness of the nylon-6 plate was cut into the dimensions of 115 mm x 100 mm. The sliced plates were then joined through the FSW process using ST80-based tools with various parameters in the shoulder to pin diameter ratio (D/r ratio) of 10/3, 15/3, and 20/3 and feed rates (FR) of 4 mm/minute, 6 mm/minute, and 8 mm/minute at a rotational speed (RS) of 5800 RPM. Afterward, the weld joint is cut using water jet cutting according to the tensile testing standard ASTM D638 type IV. Following this, characterization of the speci-mens, including macrograph examination, hardness testing, and tensile testing, was carried out. The results show that the highest tensile strength was obtained at a tool diameter ratio of 10/3 mm with a feed rate of 6 mm/minute, with a tensile strength value of 19 MPa reaching up to circa 90% of joint efficiency. The strength of the welded joint then decreases as the diameter ratio of the tool increases with each feed rate. Some defects appeared at the higher tool diameter ratios welded joint, including incomplete fusion, flash, thinning, and lack of bonding. In conclusision the combination of a D/d ratio of 10/3 and a FR of 6 mm/min at RS 5800 RPM can provide the optimal conditions for a strong nylon-6 friction stir welded joint.