Edge Trimming Process Research Articles

Effect of Cutting Speed and Feed per Tooth on the Trimmed Surface Roughness and Tool Wear During Milling of CFRP: Aerostructural Part

The machining quality plays a pivotal role in determining the service life of components. In this context, the primary focus of the experimental investigation is centered on the impact of cutting conditions during edge trimming of carbon fiber reinforced plastics (CFRP) material. The ultimate objective of this experiment is to pinpoint the most effective machining parameters, specifically the cutting speed, Vc and the feed per tooth, fz, to minimize damages during the edge trimming process using actual aerostructural sample components composed of CFRP material. Furthermore, the study took into account the issue of tool wear on cutting tools. The Design of Experiment (DoE) technique, specifically the Taguchi L9 orthogonal arrays method, was used to conduct this research. It was shown that the feed per tooth, fz, and the cutting speed, Vc, had the biggest effects on the trimmed surface quality as the longitudinal surface roughness increased. It was demonstrated that the fracture of the pyramidal tooltips in router-type tools happened more frequently at higher cutting speeds, Vc. The optimal machining parameters for minimizing damages during CFRP edge trimming were the combination of the feed per tooth, fz at 0.05 mm and cutting speed, Vc at 50 m/min. The most significant element influencing the tool’s wear was the cutting speed, Vc.

Tool wear prediction in edge trimming of MD CFRP considering interlaminar effect

The tool flank wear progresses rapidly in edge trimming of carbon fiber reinforced polymer (CFRP) components, affecting the machined surface quality and process efficiency. This paper presents a tool wear prediction method considering the unique interlaminar effect of the multi-directional (MD) CFRP in the edge trimming process. The experimental results show that different laminar configurations of MD CFRP change the tool wear progression of unidirectional (UD) plies at specific fiber orientations. The interlaminar effects from the adjacent layers with different fiber orientations are explained by their varying supporting strengths on the target layer due to the change of bouncing back height. Therefore, the interlaminar effect from two sides of a UD ply is not a simple summation of the contributions by the individual side. The machined surface roughness of unidirectional ply varies up to 30 % due to the interlaminar effect. A long short-term memory (LSTM) - back propagation (BP) network is developed to predict tool wear length, including the effect of different interlaminar configurations. With the proposed model, the effect of the interlaminar configurations on tool wear progression in edge trimming of MD CFRP is predicted quantitatively. The prediction of the wear length progression based on the developed machine learning model is validated by the experimental results.

Thermal Aspects in Edge Trimming of Bio-Filled GFRP: Influence of Fiber Orientation and Silica Sand Filler in Heat Generation.

The present work aims to determine the influence of Glass Fiber-Reinforced Polymer (GFRP) laminating configuration in heat generation during the dry edge trimming process. Temperature measurement experiments were conducted on pure epoxy matrix, 15% unidirectional glass fiber reinforced epoxy, and 28% silica sand-filled GFRP specimens through eight type-K thermocouples evenly distributed along the trim plans and connected to a data acquisition system. Infrared thermographic measurements were also conducted to investigate the tool temperature evolution while processing. It was found that perpendicular fiber edge milling induces a sharp increase with peak temperature measurements reaching 119 °C, while machining parallel to fiber leads to a maximum temperature history of 41 °C, which is very close to that obtained from the pure epoxy test. It was also found that the addition of silica sand grains in the GFRP matrix reduces both tool and specimen temperature magnitudes up to 67% for 90° plies and 14% for 0° plies compared to silica sand-free composite initial values. The heat partition was calculated from the measured (electric) and estimated energies for the tool, the workpiece, and chips, respectively. It appears from predictions that the addition of silica sand grains increases the heat conductivity of the GFRP materials (with rates of 20% for 0° fiber orientation and 10% for 90° fiber direction), while it reduces that conducted to the milling tool. Scanning Electron Microscopy (SEM) inspections helped detect the dominating machining defects relative to each GFRP configuration and explained the heat generation and dissipation effects in light of peak temperature measurements.

Simulation and experimental analysis on influences of axial cutting-induced vibration on edge trimming quality of Carbon Fiber Reinforced Plastics

In the edge trimming of Carbon Fiber Reinforced Plastics (CFRP), the workpiece is usually placed with a sufficient length projecting from the clamps for leaving enough cutting room. Owing to the weak constraint of the cutting region in the direction of the tool-axis, the cutting-induced vibration along that direction (i.e. the axial vibration) is unavoidable. In that situation, the removal process of the fiber which originally has different fracture modes is more complicated, making it becomes a challenge to realize the high-quality material removal. Focusing on this issue, this study conducts 3D mesoscopic cutting simulation for analyzing the fiber removal processes of the middle and surface layers of the CFRP workpiece under the axial vibration for the first time. The simulation is performed with high accuracy by adopting our newly proposed fiber fracture criteria correlated with the specific stress state corresponding to each fracture mode. With the obtained results, the influence mechanisms of the axial vibration on the edge trimming quality of CFRP are comprehensively revealed. The results suggest that the axial vibration can distribute the fiber bending deformation into different directions, thereby suppressing the machined surface cavities of the middle layer. However, for the surface fiber, the axial vibration can cause large out-of-plane deformation of the fiber in the unconstrained side, which aggravates the surface damages. On the basis of the results, the optimal control principle of the axial cutting-induced vibration is proposed. Moreover, a technological reference for reasonably controlling the axial vibration in the practical edge trimming process is also provided.

Temperature Study during the Edge Trimming of Carbon Fiber-Reinforced Plastic [0]8/Ti6Al4V Stack Material

Carbon Fiber-Reinforced Plastic (CFRP) and Titanium alloy (Ti6Al4V) stacks are used extensively in the modern aerospace industry thanks to their outstanding mechanical properties and resistance to thermal load applications. Machining the CFRP/Ti6Al4V stack is a challenge and is complicated by the differences in each constituent materials’ machinability. The difficulty arises from the matrix degradation of the CFRP material caused by the heat generated during the machining process, which is a consequence of the low thermal conductivity of Ti6Al4V material. In most cases, CFRP and Ti6Al4V materials are stacked and secured together using rivets or bolts. This results in extra weight, while the drilling process required for such an assembly may damage the CFRP material. To overcome these issues, some applications employ an assembly that is free of bolts or rivets, and which uses adhesives or an adapted curing process to bond both materials together. The present research analyzes a thermal distribution and its effect on quality during the edge trimming process of a CFRP/Ti6Al4V stack assembly. Different types of tools and cutting parameters are compared using thermocouples embedded within the material and others on the tool cutting edge. In contrast to previous studies, the feed rate was the most significant factor affecting the cutting temperature and quality of the workpiece, while the cutting speed had no significant impact. The temperature in the workpiece increases as the feed per tooth decreases.

Suppressing vibrations in milling-trimming process of the plate-like workpiece by optimizing the location of vibration absorber

Abstract Milling-based trimming process is a commonly used machining means for shaping the edges of the plate-like workpieces, some of which are usually designed as zigzag shapes because of the functional requirements such as the invisibility of aircrafts. Dynamic vibrations occurring in this kind of process seriously reduces the specified accuracy of the edges, while their controlling means are seldom reported in the existing works. This article presents a method by using an additional dynamic vibration absorber (DVA) to control the vibrations in the milling-based edge trimming process of the plate-like workpieces. Instead of treating the DVA as a lumped mass widely adopted by previous researchers, the layout, shape and size of the DVA are actually taken into account in this article. A simulation-and-analysis-combined approach for predicting the modal parameters of the workpiece under different layouts of the DVA is proposed. Effect of the DVA on the multi-dominant modes and response of the workpiece is theoretically studied. To realize mitigating the dynamic displacements of the workpiece during the whole milling process to the largest degree, an optimization algorithm aiming at minimizing the displacement amplitude of the in-process cutting point and also finding the best location of the absorber on the workpiece is mathematically derived. The effectiveness of the proposed method is validated by a series of milling experiments.

Influence of Router Tool Geometry on Surface Finish in Edge Trimming of Multi-Directional CFRP Material

The use of carbon fibres reinforced plastic (CFRP) composites material for product structures has been steadily increasing due to the superior material properties such as high strength, low weight and corrosion resistance especially in aerospace industry. This work presents a research on the influence of various router or burrs tool geometrical feature towards surface roughness in edge trimming process on a specific CFRP material. CFRP panel which measured in 3.41mm thickness with 28 plies in total has been chosen to be the main study material. Three various geometrical features of router tool made of uncoated tungsten carbide material with diameter of 6.35mm which vary in number of flute and helix angle were utilized to investigate the effect of surface roughness in edge trimming of CFRP material. Surface roughness measurement was taken using Mitutoyo Surftest SJ-410. Furthermore, optical microscope Nikon MM-800 is utilized to further observe the trimmed surfaces. The result reveals that tool type 3 (T3) resulted the lowest surface roughness with respect to the overall averaged Ra value which ranged between 2.22µm to 5.29µm whilst tool type 1 (T1) obtained the highest Ra values ranged between 2.86µm to 19.36µm. On the other hand, the tool type 2 (T2) falls in the middle between the rests of two others type of tool which stated the range of Ra average value was between 3.91µm to 5.28µm. This result is also supported by photomicrographs observation taken by optical microscope which elaborated and discussed further in this paper.

Experimental Investigation of Bouncing-Back of Multidirectional CFRP Laminates during Ultrasonic Assisted Edge Trimming

Edge trimming process is needed for finishing CFRP components to the required accuracy and surface quality. The bouncing–back effect of CFRP components is very challenging owing to spring back of trimmed edge after cutting tool pass. Ultrasonic assisted machining (UAM) is an efficient method used to enhance the quality of CFRP parts due to the reduced contact time between the tool and workpiece. This paper experimentally investigates the effect of edge trimming variables on the cutting forces and the magnitude of the bouncing back. Diamond abrasive end mills were utilized during ultrasonic assisted edge trimming of CFRP. The processes variables include spindle speed, feed rate, radial depth of cut, fiber orientations, and up/down strategy. Statistical analysis was conducted to determine the most significant factor on performance characteristics. Regression equation was also developed to predict the value of bouncing back. The results showed that depth of cut and feed rate have a significant effect on bouncing back among the process variables.

Edge Trimming Analysis for Surface Quality of Hybrid Composite - CFRP/Al2024

The application of hybrid composite materials has increased due to their strength and light weight ratio. Edge trimming of these materials was extremely difficult due to the anisotropic and non-homogeneous structures of CFRP and ductile nature of aluminium. This research was focused on edge trimming process via down milling operation. Three cutting parameters were examined namely spindle speed, feed rate and depth of cut. The extension of two level full factorial design, Centre Composite Design (CCD) was used to plan systematic experimental methodology. The analysis of the influence and the interaction factors associated to surface quality was studied. The objective was to obtain machined surface quality of CFRP/Al2024 between 0.4 µm to 0.6 µm. The depth of cut was the most significant factor for Al2014 and meanwhile the spindle speed and feed rate were significant factors of CFRP. The validation experiment was conducted at optimum level of recommendation control factors setting to compare the deviation of predicted value from actual/measured value. Surface roughness of CFRP was found to be at 0.594 micron at the setting of spindle speed, 11750 rpm, feed rate, 750 mm/min and depth of cut, 0.255 mm. For Al2024, the surface roughness was found to be at 0.32 micron.

Karbon Fiber Takviyeli Polimer Kompozitlerin Kenar Budama Değişkenlerinin Yüzey Kalitesine Etkisi

The main focus of this paper is to investigate the surface quality and machinability of the edge trimming process of carbon fiber reinforced polymer (CFRP) material. Measurement of transverse and longitudinal surface roughness and deformation behavior are carried out for different combinations of cutting speed, feed per tooth, tool type and milling type to evaluate the machined surface quality. Three different flutes (2,4,6) micro grain carbide end mill tools were used for vertical and inclined peripheral milling. Edge trimming experiments were conducted under different experimental parameters and their levels according to the Taguchi design of experiment method. The contribution ratio of parameters on machinability outputs has statistically analyzed by Analysis of Variance (ANOVA). According to machinability outputs such as surface roughness and deformation types, the inclined peripheral milling is more suitable than vertical peripheral milling. Edge trimming by vertical peripheral milling generates Type II delamination which consists of long uncut fibers protruding from the trimmed edges. Edge trimming by inclined milling generates Type I-II delamination which consists of short uncut fibers protruding from the trimmed edges and where plies have broken inwards in the same time. The transverse and longitudinal surface roughness and deformation decreased with increased number of teeth, cutting speed and decreased feed per tooth. The best machining quality was obtained when cutting at the highest level of cutting speed, lowest feed rate and 6 number of flute in inclined milling.

Effects of cutting edge radius and fiber cutting angle on the cutting-induced surface damage in machining of unidirectional CFRP composite laminates

Carbon fiber reinforced polymer composite laminates are anisotropic, inhomogeneous, and mostly prepared in laminate form before undergoing the finishing operations. The edge trimming process is considered as one of the most common finishing operations in the industrial applications. However, the laminate surface is especially prone to damage in the chip formation process, and the most common damage mode is burrs. Burrs may increase cost and production time because of additional machining; they can also damage the surface integrity. Many studies have been done to address this problem, and techniques for reducing burr size in material removal process has been the focus of the research. Nonetheless, the combined effects of the cutting edge radius and the fiber cutting angle on the burr formation have seldom been conducted, which in turn restricts to find out the mechanism of burr formation. The purpose of the present paper is to study the particular mechanism that leads to burr formation in edge trimming of CFRP laminates and investigate the effects of fiber cutting angle and cutting edge radius on burr formation. The results indicate that the burrs are prone to form in the fiber cutting angle range of 0° < χ < 90° when a large cutting edge radius of the tool is used for both milling and drilling of CFRP composites.

Edge trimming for surface activated dielectric bonded wafers

The impact of the edge trimming process on permanently bonded wafers is described. The edge trimming process is a blade sawing process applied on the Si wafer edge and bevel, removing the fragile edge of the wafer prior to grinding. We investigated two routes for the integration on permanently bonded Si wafers, edge-trim before bonding and edge-trim after bonding. The impact on the subsequent processes for both integration routes is assessed. For the case of edge-trim before bonding, a combination of functional water cleaning such as ozone dissolved in water and ammoniac scrub cleaning shows a significant effect to remove Si residues, enabling void free dielectric bonding. For the case of edge-trim after bonding, utilizing a small grit diamond blade shows no mechanical failures into the dielectric bonding interface. These proposed processes are a very promising for the fabrication of extreme thinned Si without mechanical failure at wafer edge.

Energy based phenomenological model for optimizing the sheared edge in the trimming of steels

Attributes related to the dimensional quality of hot rolled steels are very important in commercial sectors that make direct use of this product, because delay or equipment damage can be avoided when forming in downstream operations. In this research, the steel sheet edge trimming process and its relationship with the defect known as broken edge is experimental and numerically studied. The type of material, horizontal clearance between knives and the energy spent during the cutting process are analyzed in detail. A metal-mechanical study is carried out for obtaining a microstructural hardness and flow stress characterization. Consequently, the edge trimming process is FEM simulated and its results in relation to knife penetration and shear stress lead to determining the energy spent during the cutting process. A mathematical model is determined under the consideration that minimum energy gives the optimum cutting conditions. The model proposes a reliable value for the horizontal clearance (Hc), between knives, taking as the principal factors: energy consumed during the edge trimming process, sheet thickness (Th), carbon content (C) and/or its ultimate tensile strength, expressed as: Hc=α+βTh−γC. A comparison of the recommended numerical results with the best practical conditions is carried out and a high coincidence is successfully found. This model is expected to be easily adopted as a tool where operators can adjust and control the parameters of process, and then, as a result, produce a sheet without edge trimming defects as well as a reduction in efficiency costs.

Temperature Measurement in CFRP Milling Using a Wireless Tool-Integrated Process Monitoring Sensor

Interrupted, high-speed composite machining processes involving complex geometries in rotation remain without a robust and accurate temperature process-monitoring tool. In this investigation a novel wireless integrated thermocouple (WIT) sensor for low-temperature applications (&lt;200°C) is characterised for tool-side temperature measurement in peripheral milling. The signal from the WIT sensor within the tool material is assessed and a parametric finite element (FE) model is generated to improve the accuracy of temperature measurement and infer characteristics of the thermal behaviour of the tool during cutting. The model is validated using a cuttinganalogous heat delivery experimental setup. Using the validated parametric model, heat fluxes and surface temperatures are investigated in a carbon-fibre reinforced polymer (CFRP) edge trimming case study. The combination of the raw WIT response and the parametric model demonstrate an ability to improve the capability of the CFRP milling process by allowing for accurate tool-side prediction of temperatures for a range of machining parameters. Results demonstrate the performance of the WIT sensor with FE model incorporated for a CFRP edge trimming process.

Modeling of Delamination During Milling of Unidirectional CFRP

The production of CFRP needs edge trimming in order to remove burrs as well as undefined orientated fibres and to shape the final part contour. Edge trimming is usually done by contour milling. The quality of machined edges may be affected by fibre protrusions and delaminated fibres which cause manual repair or may even lead to scrap.Delamination of fibres is often initiated by stresses applied during engagement of the cutting edge. Based on measured cutting forces, the stress distribution and the inter fibre fracture modes in the boundary zone of the machined surface are calculated using Lekhnitskii's theory of elasticity for anisotropic elastic bodies and the fracture criteria of Puck.In course of the continuing edge trimming process, fibre ends in the damaged boundary zone might not be cut off but deflected by subsequent tool engagements, as can be observed in high speed videos. In the case of existing fibre protrusions, a relation between the minimum depth of the damaged zone, the fibre orientation at the machined edge and the fibre properties was derived using elementary bending models. The analysis underlines the existence of only one type of surface ply delamination i.e. fibre protrusions and fibre delamination always occur together.