The additive manufacturing sector is rapidly developing, providing alternatives for mass production in the polymer composite industry. Due to the direction-dependent mechanical properties and high cost of fiber-reinforced polymeric materials, it is necessary to take advantage of alternative multi-materials and production technologies. In this study, a special geometric-shaped knitting technique was investigated using two different materials. The main material was polyamide 6 (PA6), and the inner or second material was PA6 with a 30 wt.% glass fiber addition by weight (PA6GF30). The special geometric shape, layer thickness, nozzle temperature, and post-heat treatment time were measured as process parameters in the production of the PA6/PA6GF30 composites with the fused deposition modeling (FDM) technique. The Taguchi design method and L9 fractional experiment were used in the experimental study. The mechanical behaviors of the PA6/PA6GF30 samples were obtained using tensile and impact tests. In addition, scanning electron microscopy (SEM) analyses were performed on the fracture lines of the PA6/PA6GF30 samples, and damage analyses were carried out in more detail. The experimental results were sorted using grey relational analysis (GRA). Moreover, the optimal experimental conditions and their related plots were obtained. As a result, the highest tensile strength of the PA6GF30 composite was 89.89 MPa with the addition of a special geometric shape. In addition, the maximum impact resistance value of the PA6/PA6GF30 composite was 83 kJ/m². Hence, the developed knitting method presented many advantages when using the FDM technique, and both were successfully used to produce the PA6/PA6GF30 composites.

In recent years, plastic decorative materials have been used in the automotive industry due to their advantages such as being environmentally friendly, aesthetic, light and economically affordable. Plastic decorative materials can exhibit high strength and metallic reflection with metal coatings. Chrome plating is generally preferred in the production of decorative plastic parts in the automotive industry. In this study, the effect of injection molding processing parameters on the metal–polymer adhesion of chrome-plated acrylonitrile butadiene styrene (ABS) was investigated. The ABS-based front grille frames are fabricated by means of using an industrial-scale injection molding machine. Then, the fabricated ABS-based front grille frame was plated with chrome by means of the electroplating method. The metal–polymer adhesion was investigated as a function of the injection molding processing parameters by means of a cross-cut test and scanning electron microscope (SEM). As a result, it was determined that the optimal injection process parameters, a cooling time of 18 s, a mold temperature of 70 °C, injection rates of 45-22-22-20-15-10 mm/s, and packing pressures of 110-100-100 bar, were effective in enhancing polymer–metal adhesion for the ABS-based front grille frame.

The fabrication of thin-walled plastic parts has potential in the automotive industry in terms of sustainability and circular economy targets to decrease any harmful effects on the ecosystems, cost and performance. Injection molding of thin-walled automotive parts is more complex in terms of processing defects compared to traditional plastic parts. Optimization of processing parameters is of critical importance to solving problems and defects in the production of thin-walled parts. In this study, the flow length and weight of thin-walled spiral parts (with wall thicknesses of 0.50, 1.50, 2.70 and 3.00 mm) were investigated with theoretical and experimental studies. The theoretical flow length and weight of the thin-walled spiral parts were determined by Moldflow analysis according to the pressure and wall thickness. The correlation graph between theoretical results and experimental measurements was obtained. When the wall thickness of the thin-walled spiral parts increased, the flow length of the thin-walled spiral parts increased. As a result, it was found that the thin-walled spiral part mold could not be filled for wall thicknesses of 0.50 and 1.50 mm at maximum pressure due to decreasing temperature at the flow front. In addition, the thin-walled spiral part mold can be filled for a wall thickness of 2.70 and 3.00 mm. In the correlation study conducted for these values, an agreement of approximately 90% was achieved. However, it was also observed that as the pressure increases, the deviation between the experimental and theoretical results becomes more pronounced.

Poly (vinyl chloride) (PVC) is widely used in many products due to its increased flexibility and processability. It is preferred in many industrial applications, especially in the plasticized PVC cable industry due to its excellent insulation properties. PVC is quite hard and can be difficult to process. Therefore, it requires additives such as plasticizers. Plasticizers typically reduce the glass transition temperature (Tg) and provide flexibility by reducing the workable temperature level. In the PVC compound production industry, phthalate-based plasticizers are preferred due to their low cost. Commonly used plasticizers are adipates, azelates, trimethylates, phthalates, benzoates, and chlorinated paraffins. The aim of the study was to investigate the plasticizer changes in PVC compounds used in cable insulation applications by synergistic effects of adipate, trimellitate, and phthalate-based plasticizers such as dioctyl terephthalate (DOTP), 2-ethyl hexyl adipate (DOA), and tris(2-ethylhexyl) benzene-1,2,4-tricarboxylate (TOTM). In this study, the effects of plasticizer additives were investigated on the structural, morphological, thermal, and mechanical properties of PVC compounds in the cable industry. Fabricated test products were characterized using characterization methods such as Fourier transform infrared-attenuated total reflectance (FTIR-ATR), scanning electron microscope–energy-dispersive X-ray (SEM-EDX) spectroscopy, thermal gravimetric analysis (TGA), tensile test, and density test. Successfully fabricated samples were tested before and after aging. The highest elongation at break of PVC flat sheet (244.96%) was obtained with the use of DOA plasticizer. The highest tensile strength was measured as 17.85 MPa for the sample containing 50 phr DOTP. Furthermore, no significant mass loss was observed up to 238 °C, while substantial decomposition occurred in the samples containing 50 phr DOTP, 50 phr DOA, and 50 phr TOTM between 238–338 °C, followed by gradual degradation at 483 °C and 683 °C. As a result, it has been determined that the use of DOA plasticizer in PVC compounds used in the cable industry is more effective than DOTP and TOTM plasticizers.