Cutting parameters optimization in edge trimming of UD-GFRP composites with diamond coated burr tools
Topic(s) : Manufacturing
Co-authors :
Benoît SCHRAB (FRANCE), Anne COLLAINE , Jean-Marie FREYBURGER , Michel TOURLONIAS (FRANCE)Abstract :
In the manufacturing process of fiber reinforced polymers (FRP), machining operations are generally required. These operations notably include edge trimming to finish the periphery of the part and drilling for fastening purposes [1]. FRP machining is governed by specific cutting mechanisms and may generate many types of defects (uncut fibers, fiber pullout, delamination, matrix degradation…) [2]. Cutting tools with specific geometries like burr tools contribute to reduce such defects occurrence. Indeed, burr tools consist of many pyramidal teeth aiming to avoid axial forces associated with conventional helical geometries [3] which may generate delamination and uncut fibers on external plies [2].
Many research works were carried out on carbon fiber reinforced polymers (CFRP) milling with burr tools, especially about cutting parameters optimization. In particular, several studies recommended a low feed speed to achieve a good surface finish and to minimize defects occurrence [4], [5]. Some authors also recommended low cutting speeds [5] while high cutting speeds were advised by others [4]. Besides, the temperature during cutting was reported to be particularly affected by the cutting speed [6]. These studies focused on multidirectional composites and thus results may depend on the stacking sequence of the material. Indeed, it is well known that FRP cutting mechanisms are governed by fiber orientation.
Therefore, the goal of this study is to investigate the effect of cutting parameters (including cutting speed and feed per tooth) on machining quality, cutting forces and machined surface temperature in edge trimming of unidirectional (UD) composites with selected fiber orientations using burr tools. Edge trimming tests are carried out on glass fiber reinforced polymers (GFRP) which are widely used in many applications. Highly wear resistant diamond coated burr tools are used for the experiments (Figure 1) in order to minimize any wear related effect. Cutting forces are recorded in the three space directions synchronously with the machined surface temperature. The machining quality is characterized in terms of surface texture along with uncut fibers on the external layers which are quantified using a dedicated imaging device and specific processing.
The first results show that machining quality, cutting forces and machined surface temperature are affected by cutting parameters. An optimization criterion is the productivity that can be evaluated by the material removal rate (MRR). Increasing the MRR with a higher feed rate generates greater cutting forces and higher surface temperature. However, at constant MRR the combination of an increase in cutting speed and a decrease in feed per tooth tends to reduce average cutting forces (Figure 2). Itmay also lead to a higher surface temperature for some fiber orientations while this is not the case for others (Figure 2), showing the influence of the cutting mechanisms related to fiber orientation [1].
Many research works were carried out on carbon fiber reinforced polymers (CFRP) milling with burr tools, especially about cutting parameters optimization. In particular, several studies recommended a low feed speed to achieve a good surface finish and to minimize defects occurrence [4], [5]. Some authors also recommended low cutting speeds [5] while high cutting speeds were advised by others [4]. Besides, the temperature during cutting was reported to be particularly affected by the cutting speed [6]. These studies focused on multidirectional composites and thus results may depend on the stacking sequence of the material. Indeed, it is well known that FRP cutting mechanisms are governed by fiber orientation.
Therefore, the goal of this study is to investigate the effect of cutting parameters (including cutting speed and feed per tooth) on machining quality, cutting forces and machined surface temperature in edge trimming of unidirectional (UD) composites with selected fiber orientations using burr tools. Edge trimming tests are carried out on glass fiber reinforced polymers (GFRP) which are widely used in many applications. Highly wear resistant diamond coated burr tools are used for the experiments (Figure 1) in order to minimize any wear related effect. Cutting forces are recorded in the three space directions synchronously with the machined surface temperature. The machining quality is characterized in terms of surface texture along with uncut fibers on the external layers which are quantified using a dedicated imaging device and specific processing.
The first results show that machining quality, cutting forces and machined surface temperature are affected by cutting parameters. An optimization criterion is the productivity that can be evaluated by the material removal rate (MRR). Increasing the MRR with a higher feed rate generates greater cutting forces and higher surface temperature. However, at constant MRR the combination of an increase in cutting speed and a decrease in feed per tooth tends to reduce average cutting forces (Figure 2). Itmay also lead to a higher surface temperature for some fiber orientations while this is not the case for others (Figure 2), showing the influence of the cutting mechanisms related to fiber orientation [1].