Effect of tool wear on cutting forces in the orthogonal cutting of unidirectional glass fibre-reinforced plastics

doi:10.1016/1359-835X(95)00034-Y

Composites Part A: Applied Science and Manufacturing

Volume 27, Issue 5, 1996, Pages 409-415

https://doi.org/10.1016/1359-835X(95)00034-Y Get rights and content

Abstract

Orthogonal cutting tests were carried out on unidirectional glass fibre-reinforced plastic composites, holding the cutting direction parallel to the fibre direction. The tools were made of high speed steel, with rake angle α = 0°; two relief angles γ, namely 7° and 15°, were adopted. A very low cutting speed was utilized, in order to avoid thermal effects on both the tool and the work material. The experimental results show that, under the selected operating conditions, the tool wear essentially consists of a very rapid rounding of the tool nose (nose wear). The face wear evolution is practically independent of the relief angle, whereas the latter affects the flank wear rate, which is slightly lower for the higher γ value. Both the horizontal and the vertical cutting forces exhibit notable increases with tool wear. The force data are interpreted in the light of a previously presented model, aiming to predict cutting forces as a function of the cutting parameters. It is shown that the observed increase in the horizontal force can be simply attributed to the increase in the vertical force at the tool flank, whereas the chip-tool interaction forces occuring at the tool face seem to be unaffected by wear phenomena. Finally, a strict correlation is found between the flank wear and the recorded vertical force variations.

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Glass fiber reinforced plastics (GFRP) are widely appiled for high-value components, but it faces limitations due to the heterogeneity and limited milling tool life. This study investigates the wear mechanism of tools in varying states of wear during the milling of GFRP under different combinations of cutting parameters. The findings demonstrate a significant increase in flank wear values of new tools, initially worn tools, moderate worn tools and severely worn tools associated with the large material removal rate (LMRR), exhibiting respective increments of 56.7%, 59.8%, 74.3%, and 26.5% in contrast to the small material removal rate (SMRR). The wear mechanisms in distinct cutting regions of the tool were systematically classified and characterized. The flank face and tool nose primarily experience abrasion and adhesion, while the rake face and cutting edge predominantly display characteristics of microchipping and abrasive wear. In contrast, the bottom edge is exclusively impacted by microchipping. The deposition of chemical elements on the cutting edge was examined through electron dispersive spectroscopy (EDS) and scanning electron microscopy (SEM). A comprehensive investigation was undertaken to elucidate the progression of tool wear. The findings indicate that the principal factors influencing tool wear in LMRR are adhesive wear resulting from cutting heat and chipping wear arising from substantial cutting loads. In contrast, tool wear during SMRR is predominantly attributed to abrasive wear caused by the presence of fiber-based hard points within GFRP workpieces. The wear characteristics of milling tools during the machining of GFRP are systematically investigated and analyzed. This study holds theoretical significance in guiding the design of tool materials for GFRP milling operations.
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This paper introduces a novel indirect tool condition monitoring (TCM) system for micro-milling brittle materials (glass and silicon) based on acoustic emission (AE) and cutting force signals. The milling experiments are also applied to a ductile material (steel) for comparison. Tool wear calibration is conducted to determine the three tool wear stages. The collected signals are processed in time, frequency, and time-frequency domains. Specific frequency subrange combinations of cutting force signals in three directions after wavelet packet decomposition show strong correlation to the tool wear stages, whilst processed AE signals are the secondary feature to the tool wear. A tool wear prediction model for each material is built based on all the chosen features and back propagation (BP) neural network. The prediction model is simply structured and highly efficient with the highest prediction accuracy of more than 95%.
An approach on capturing the influence of the stochasticity of fibre distributions for modelling the variability of cutting forces in composite materials
2017, Composites Part B: Engineering
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Only few researchers focused on the cutting scenarios of across and parallel fibre orientations (see Fig. 1b and c). Caprino et al. [19] investigated the influence of the tool wear on cutting forces in parallel fibre orientation composite, while Pramanik et al. [20] studied the surface damage and tool wear in cutting across oriented fibre for metal matrix composites. However, neither of their work gave any model or method to predict cutting forces during the machining process of composite materials considering fibre location stochasticity.
The paper presents a novel model to evaluate the variation of orthogonal cutting forces for randomly distributed unidirectional fibres when cutting composite structures. The distribution analysis of fibre locations is first introduced into this topic, and has been experimentally validated, resulting in a Gaussian distribution based random method to simulate the stochastic fibre locations within composites. The dedicated cutting force model divides the resultant forces into fibre and matrix cutting forces, and for the first time is able to predict the force variations corresponding to the stochastic fibre distributions. The orthogonal cutting of unidirectional fibre composite is classified into three cases based on the relation between the tool feed direction and the fibre orientation, all these cases are taken into account to validate the proposed model. The validation shows that both cutting forces and fibre locations follow the Gaussian distribution with a standard error lower than one percent, and the simulated fibre locations show a satisfactory agreement with the real composite internal structure during distribution analysis. Furthermore, the predicted cutting forces coincide with the experimental data, especially their variations evaluated by probability density function and cumulative distribution function demonstrate the high degree of consistency between them. This work also indicates the proposed modelling framework could be of high relevance to other relevant applications, such as energy consumption and tool wear estimation, where the understanding of the dynamic cutting forces is crucial.
Modelling of cutting fibrous composite materials: Current practice
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Using fibre reinforced polymers (FRP) is increasing across many industries. Although FRP are laid-up in the near-net shape, several cutting operations are necessary to meet quality and dimensional requirements. Modelling of cutting is essential to understand the physics of the cutting phenomena and to predict quality and cost of products. This paper aims at reviewing the current practice in modelling of cutting FRP including analytical, numerical, mechanistic and empirical approaches, with emphasis on analytical models of cutting forces and delamination. Processes detailed include orthogonal cutting, drilling, milling and turning. Finally, advances in machining of metal-composite stacks are presented.
Rigorous treatment of dry cutting of FRP - Interface consumption concept: A review
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The main tools used in cutting FRP might be classified into four main groups according to their hardness, strength and toughness: (i) high speed steels (HSS), (ii) cemented carbides, (iii) ceramics and (iv) super-hard materials. Efficiency of steel-based tools versus FRP composites has been widely investigated since the 1980s [3,9,11,17,37,58,62,63,69]. They possess the highest toughness and the lowest strength and hardness.
The meticulous analysis of the most met mechanisms involved when cutting fiber reinforced polymers (FRP) has a pivotal role in improving part availability, informing the processes used and preventing catastrophic results. So far, the terminology used for qualifying the phenomena encountered when cutting FRP still remains frequently inspired from single phase alloys while observable mechanisms are often strikingly different. This is the main reason that motivates this study to elucidate proper FRP mechanisms against other alloys i.e. metals. After criticizing the most common operations of the open literature by examining the interactions experimentally revealed for given tool–material pairs, the material removal process versus composite type, tool type and operating conditions is addressed. A special focus is put on correlating the material removal mechanisms with the material removal “volume” frequently qualified as a “chip,” through interface consumption concept. The material separation mechanisms and morphology of the produced “chip” are discussed in details versus both fiber orientation and cutting variables. Based on the fundamental inspections of experimental studies, the wear land and mechanisms are properly classified versus the tool grade. While experimental trials seem to be challenging, the analytical and numerical approaches show ability to access some cutting outputs although with several limitations. The macro- as well as micromechanical models were built focusing on how to manage the numerical inputs for predicting at best the cutting behavior. Modeling of the fiber–matrix interface and tool–material contact were closely discussed.
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Laser machining has great potential regarding automation in fabrication of CFRP (carbon-fiber-reinforced plastics) parts, due to the nearly force and tool-wear free processing at high process speeds. The high vaporization temperatures and the large heat conductivity of the carbon fibers lead to a large heat transport into the sample. This causes the formation of a heat-affected zone and a decrease of the process speed.
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Manufacturing paperEffect of tool wear on cutting forces in the orthogonal cutting of unidirectional glass fibre-reinforced plastics

Abstract

J. Mach. Tools Manufact.

Compos. Manuf.

Composites

Annals of CIRP

Quality definition and assessment in drilling of fibre reinforced thermosets

Annals of CIRP

Damage in drilling glass fibre reinforced plastics

Development of effective machining and tooling technique for Kevlar composite laminates

Tool life and hole quality in drilling aramid and fibrous composites

Manufacturing paper
Effect of tool wear on cutting forces in the orthogonal cutting of unidirectional glass fibre-reinforced plastics