Kerf Taper Defect Minimization Based on Abrasive Waterjet Machining of Low Thickness Thermoplastic Carbon Fiber Composites C/TPU

Abstract

Carbon fiber-reinforced thermoplastics (CFRTPs) are materials of great interest in industry. Like thermosets composite materials, they have an excellent weight/mechanical properties ratio and a high degree of automation in their manufacture and recyclability. However, these materials present difficulties in their machining due to their nature. Their anisotropy, together with their low glass transition temperature, can produce important defects in their machining. A process able to machine these materials correctly by producing very small thermal defects is abrasive waterjet machining. However, the dispersion of the waterjet produces a reduction in kinetic energy, which decreases its cutting capacity. This results in an inherent defect called a kerf taper. Also, machining these materials with reduced thicknesses can increase this defect due to the formation of a damage zone at the beginning of cut due to the abrasive particles. This paper studies the influence of cutting parameters on the kerf taper generated during waterjet machining of a thin-walled thermoplastic composite material (carbon/polyurethane, C/TPU). This influence was studied by means of an ANOVA statistical analysis, and a mathematical model was obtained by means of a response surface methodology (RSM). Kerf taper defect was evaluated using a new image processing methodology, where the initial and final damage zone was separated from the kerf taper defect. Finally, a combination of a hydraulic pressure of 3400 bar with a feed rate of 100 mm/min and an abrasive mass flow of 170 g/min produces the minimum kerf taper angle.

Surface Quality and Free Energy Evaluation of s275 Steel by Shot Blasting, Abrasive Water Jet Texturing and Laser Surface Texturing

“…Abrasive water jet machining [33] as a texturing technology can be a technology capable of modifying large surfaces in a controlled manner and with shorter texturizing times than those obtained by blasting and laser texturizing.…”

A Review on the Abrasive Water-Jet Machining of Metal–Carbon Fiber Hybrid Materials

“…For the calculation of Wt, the distance between the upper points where the cut is considered to begin is determined. However, if the IDR defect did not exist, those points would be closer (Wt2), generating an upper width different if the points to be chosen are those generated by the IDR defect (Wt1) [41]. All these geometrical factors define the geometry generated by this technology, which are directly associated with the previous selection of cutting parameters or input parameters: hydraulic pressure (P), traverse speed (TS), abrasive mass flow (f) and the distance between the nozzle and the upper surface of the material to be machined (d).…”

“…For the calculation of Wt, the distance between the upper points where the cut is considered to begin is determined. However, if the IDR defect did not exist, those points would be closer (Wt2), generating an upper width different if the points to be chosen are those generated by the IDR defect (Wt1) [41]. Another way to calculate the obtained geometry and its taper is through the taper angle.…”

On the Surface Quality of CFRTP/Steel Hybrid Structures Machined by AWJM

“…These studies are focused on the influence of the parameters that govern abrasive water jet machining on the surface quality generated, as well as on the defectology associated with this process such as the taper angle. Although there is literature on water jet machining of thermoplastic composites [24] and steel alloy [25], little information exists on machining these materials in the form of a hybrid structure.…”