A full factorial experimental design was used to assess the importance of the drilling parameters. Digital photography technique was used to evaluate the damages from drilling. The drilling operation was assessed based on two introduced factors, including the delamination factor (DF) and uncut fiber factor (UCFF). Analysis of the experimental results for DF indicated that feed rate was the most significant parameter. On the other sides, experimental results for UCFF showed that feed rate had the greatest influence. Also, the results revealed that the both factors were increased by the increase of feed rate and there was an optimum point of cutting speed and tool diameter in the evaluation of UCFF. Drilling of balsa wood composite sandwich panel had the best quality followed by corrugated foam and PVC foam sandwich panels.

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Polyether ether ketone (PEEK) and its composites are widely used in the biomedical industry due to their superior properties. The presence of glass and carbon reinforcing particles will improve the strength of the polymers while affecting their machinability. The cutting speed, dressing speed ratio, and different reinforcing fibers were defined as input parameters. Grinding forces, specific grinding energy, surface roughness, the surface topography of the workpiece, and wheel loading ratio were selected as output parameters of this research. Surface roughness is strongly affected by heat generation in the grinding zone. The experiments showed that pure polymer, GFRP (glass fiber-reinforced plastic), and CFRP (carbon fiberreinforced plastic) induce maximum wheel loading ratio, respectively. The maximum wheel loading was calculated as 31% for pure polymer, and the main mechanism is melting. The highest cutting forces were measured when grinding pure polymer, followed by carbon, and glass fiber composites. The grinding forces were also affected by wheel loading ratio. Normal and tangential grinding forces increased up to 67% and 57%, respectively, by severe cutting conditions. The minimum specific grinding energy of PEEK and its composites was around 2.5 J/mm 3 . Additionally, increasing the cutting speed to v c = 15 m/s (despite lower inducing cutting forces) and decreasing the dressing speed ratio to q d = −0.3 surprisingly caused a rise in the roughness of the ground surfaces (for all three materials) due to a higher heat generation in the contact zone.

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Polyether ether ketone (PEEK) has been widely used in the medical engineering due to its high strength to weight ratio, creep and wear-resistance, and anti-allergically properties. Grinding is generally used to produce PEEK parts with high accuracy and surface quality requirements. In this research, the tool loading and the effect of cryogenic cooling in the grinding of PEEK are studied for the first time. It is shown that the generated heat in the grinding process, which is mainly influenced by the tool micro-topography, process parameter, and coolant lubricant has an important role in the surface integrity of PEEK. Additionally, the influence of specific material removal rate and the dressing speed ratio on the specific grinding energy of PEEK was studied. The input parameters of the grinding process that are investigated in this study include cutting speed (vs), depth of cut (ae), and feed rate (vft). To investigate the grinding wheel topography, the effects of dressing overlap ratio (Ud) and the dressing speed ratio (qd) were also investigated. Grinding force, surface roughness, and loading of the grinding wheel were considered as output parameters. The experiments were designed based on response surface methodology and the optimum cutting condition was obtained based on this method. The depth of cut and the dressing overlap ratio had respectively the maximum and minimum impact on the surface roughness and cutting forces. Additionally, the tool loading was mainly influenced by the cutting speed.