Analysis of the welding strength in hybrid polypropylene composites as a function of the forming and overmolding parameters

Abstract

This work investigates the influence of the process parameters on the welding strength in hybrid polypropylene composites manufactured by injection overmolding. A hybrid T‐joint specimen was designed to evaluate the global performance of the welding by means of tensile tests. The effects of the process parameters were evaluated in accordance the design of experiments approach and the maximum strength (UTS) was assumed as response variable. The effects of melt temperature and holding pressure, combined to a variothermal mold‐control system, were investigated. The residual stresses induced by the process were considered by means of coupled thermo‐fluid dynamic/structural finite‐element analysis. Moreover, the topography of the laminate‐side surface was characterized and the process‐induced surface modification was related to the performance of the welding. Results show that the melt temperature contributes to increase the welding strength; conversely, the mold temperature counteracts this effect by increasing the residual stress at the interface. POLYM. ENG. SCI., 58:592–600, 2018. © 2017 Society of Plastics Engineers

Modeling the Adhesion Bonding Strength in Injection Overmolding of Polypropylene Parts

“…The positive effect of the melt temperature ( Figure 3 ) was expected, as a higher interface temperature significantly promotes the macromolecular interdiffusion. The negative effect of the packing pressure was unexpected, since it is known that pressure contributes to increasing the degree of contact [ 31 ]. However, as the crystallization temperature significantly increases with pressure [ 32 ], the timeframe for molecular interdiffusion reduces.…”

“…The slots are perpendicular to the parting plane to allow the manual handling and the in-cavity positioning of the base after a preliminary IR heating. Further details about the experimental setup are described in [ 31 ].…”

“…The base was slightly clamped between the plates of the support to avoid any bending. It was secured using a steel plate with a central rectangular hole having sides 1 mm longer than the sides of the interface area [ 31 ]. The lateral surfaces of the stem were free to slide without interference with the steel plate.…”

Effect of chemical etching of resistance wire surface on the strength and failure mechanism of the resistance‐welded joint of polyetherimide composites

“…The restriction of laser welding is that the supernatant and substrate weldments must have good light transmittance and light absorption, respectively, to make the laser energy accumulate at the interface of their wielding region. 17 Therefore, it is widely used in a variety of thermoplastic composite connections, such as carbon fiber-reinforced polyetheretherketone (CF/PEEK), 18 carbon fiber-reinforced polyetherketoneketone (CF/PEKK), 19 glass fiberreinforced polyetherimide (GF/PEI), 20 carbon fiber-reinforced polyetherimide (CF/PEI), 21 glass fiber-reinforced polypropylene (GF/PP), 22 glass fiber-reinforced polyethylene terephthalate (GF/PET), 23 glass fiber-reinforced polyphenylenesulfide (GF/PPS), 24 and so on. 7 Induction welding can be used for the weldments with more complex shape and is capable of forming continuous weld of large-scale structural components.…”

“…16 Compared with other fusion bonding technologies, resistance welding has several advantages of short process flow, simple and flexible equipment, low cost, no surface treatment, and continuous welding capacity of large-scale parts. 17 Therefore, it is widely used in a variety of thermoplastic composite connections, such as carbon fiber-reinforced polyetheretherketone (CF/PEEK), 18 carbon fiber-reinforced polyetherketoneketone (CF/PEKK), 19 glass fiberreinforced polyetherimide (GF/PEI), 20 carbon fiber-reinforced polyetherimide (CF/PEI), 21 glass fiber-reinforced polypropylene (GF/PP), 22 glass fiber-reinforced polyethylene terephthalate (GF/PET), 23 glass fiber-reinforced polyphenylenesulfide (GF/PPS), 24 and so on. Various processing factors of resistance welding have been investigated to obtain stronger welded joints.…”