With stringent safety requirements, tight tolerances, and high-value components, it is imperative... more With stringent safety requirements, tight tolerances, and high-value components, it is imperative that the performance of a machine tool used in the aerospace industry is gauged prior to conducting any machining operations. Routine calibration gives confidence that a machine tool is running within specification, and will therefore be likely to produce good parts. Unfortunately, the full calibration of a machine tool is a lengthy process, making it impractical and costly to a business to run regularly – usually occurring no more than once per year. Instead, there is a necessity for machine tool health verification: a short routine that can be run regularly (i.e. once per shift, day, or week) to ensure a machine tool remains in good working order between calibrations. This research identified a number of key failure modes that can affect machine tools in aerospace manufacture and proposed solutions that could be utilised in testing for these. To fulfil this, a review of existing comme...
Machining-induced white layers and severely deformed layers are undesirable surface integrity fea... more Machining-induced white layers and severely deformed layers are undesirable surface integrity features which can be formed when machining high-strength aerospace alloys. An orthogonal milling process has been designed and performed to assess the impact of cutting speeds, tool wear, cutting edge radius and climb vs conventional milling on white layer formation and plastic strain distribution. The plastic deformation in the machined surface associated with the formation of white layers in Ti-6Al-4V has been quantified using micro-grids of different length scales printed using the electron beam lithography technique. It was found that white layers formed via the severe plastic deformation mechanism, at equivalent plastic strain values in excess of 1.2 and in regions of the cutting arc with the instantaneous chip thickness of less than the cutting-edge radius and ploughing and rubbing being the dominant mechanisms. The results indicated that the magnitude of the measured strains and the depth of plastically deformed material was greater at lower cutting speeds, during climb milling and when machining with a larger cutting edge radius and tool flank wear land.
In today's business environment, the trend towards more product variety and customization is unbr... more In today's business environment, the trend towards more product variety and customization is unbroken. Due to this development, the need of agile and reconfigurable production systems emerged to cope with various products and product families. To design and optimize production systems as well as to choose the optimal product matches, product analysis methods are needed. Indeed, most of the known methods aim to analyze a product or one product family on the physical level. Different product families, however, may differ largely in terms of the number and nature of components. This fact impedes an efficient comparison and choice of appropriate product family combinations for the production system. A new methodology is proposed to analyze existing products in view of their functional and physical architecture. The aim is to cluster these products in new assembly oriented product families for the optimization of existing assembly lines and the creation of future reconfigurable assembly systems. Based on Datum Flow Chain, the physical structure of the products is analyzed. Functional subassemblies are identified, and a functional analysis is performed. Moreover, a hybrid functional and physical architecture graph (HyFPAG) is the output which depicts the similarity between product families by providing design support to both, production system planners and product designers. An illustrative example of a nail-clipper is used to explain the proposed methodology. An industrial case study on two product families of steering columns of thyssenkrupp Presta France is then carried out to give a first industrial evaluation of the proposed approach.
Machining-induced white layers can affect the functional performance of engineered components, du... more Machining-induced white layers can affect the functional performance of engineered components, due to the resulting mechanical and microstructural properties. Destructive inspection methods such as cross-sectional microscopy are typically used to identify white layers, however, these methods are inherently costly and timeconsuming. It is, therefore, desirable to detect this anomalous surface feature using non-destructive methods which requires improved knowledge around the characteristics of white layers. The present paper reports on the characterization of white layers formed during machining of Ti-6Al-4V, to aid future development of a reliable non-destructive assessment method. The microstructure of the material in the white layer was found to have a basal-hexagonal close packed texture and there was no evidence of an phase transformation during white layer formation. The white layer has a highly refined grain structure with an increased nanohardness of up to 15% compared with the bulk material. It is proposed that white layers in Ti-6Al-4V are formed by continuous dynamic recrystallization driven by severe plastic deformation during machining. According to the measured micromechanical properties of the white layer, suitable non-destructive testing methods are suggested for the detection of this surface feature.
CIRP Journal of Manufacturing Science and Technology, 2018
The presence of machining-induced white layer in the near-surface of critical aeroengine alloys h... more The presence of machining-induced white layer in the near-surface of critical aeroengine alloys has a detrimental effect on the lifetime of a component. Present techniques for identifying and characterizing white layer, such as optical microscopy and hardness testing, whilst effective, are destructive, costly and time-consuming. Non-destructive testing methods may, therefore, offer improvements to the process of white layer detection. This paper discusses the formation mechanisms and the defining physical properties of machininginduced white layers before offering a comprehensive review of the current state-of-the-art in both destructive and non-destructive testing methods for detecting this anomalous surface feature.
Link to publication on Research at Birmingham portal General rights Unless a licence is specified... more Link to publication on Research at Birmingham portal General rights Unless a licence is specified above, all rights (including copyright and moral rights) in this document are retained by the authors and/or the copyright holders. The express permission of the copyright holder must be obtained for any use of this material other than for purposes permitted by law. • Users may freely distribute the URL that is used to identify this publication. • Users may download and/or print one copy of the publication from the University of Birmingham research portal for the purpose of private study or non-commercial research. • User may use extracts from the document in line with the concept of 'fair dealing' under the Copyright, Designs and Patents Act 1988 (?) • Users may not further distribute the material nor use it for the purposes of commercial gain. Where a licence is displayed above, please note the terms and conditions of the licence govern your use of this document. When citing, please reference the published version. Take down policy While the University of Birmingham exercises care and attention in making items available there are rare occasions when an item has been uploaded in error or has been deemed to be commercially or otherwise sensitive.
... 500 MPa. The effect of high speed milling parameters, including, flank wear (new tool/worn to... more ... 500 MPa. The effect of high speed milling parameters, including, flank wear (new tool/worn tool), cutting speed and angle-of-workpiece, on residual stress was further analysed using a Taguchi orthogonal array. This demonstrated ...
... Military work is lead by performance aspects and the requirement for engines with high thrust... more ... Military work is lead by performance aspects and the requirement for engines with high thrust-to-weight ratios, raised turbine temperatures and fewer compressor and turbine stages, all of which create ... In subsequent work by Zhang on 48-2-2 and also Mantle et al. ... Wheeler et al. ...
Experimental data is presented which compares the eect of grinding and high speed milling (HSM) o... more Experimental data is presented which compares the eect of grinding and high speed milling (HSM) on the fatigue strength of a gamma titanium aluminide intermetallic alloy. Results showed that HSM signi®cantly increased fatigue strength by as much as 200 MPa over polished samples. Measurement and analysis of workpiece subsurface microhardness and microstructure indicated that the high run-out values correlated to high hardness and plastic deformation of the near surface lamellae.
Machining data are presented for small diameter, profiled (fir tree root form), single layer/elec... more Machining data are presented for small diameter, profiled (fir tree root form), single layer/electroplated CBN (B46, B76 and 91) and diamond (D46) grinding wheels, when cutting Udimet 720. Spindles operating at 60,000 and 90,000rpm were employed, with a synthetic polyalphaolefine (PAO) oil based fluid in a down grinding mode on single sided specimens. Operating parameters were selected to reflect finishing conditions. Measured tool wear was lower for CBN grit as compared to diamond however workpiece roughness was lower with Ra approaching 0.75μm when using D46 wheels. Higher rotational speed produced lower grinding wheel wear. No workpiece burning was observed irrespective of grit type at the conditions tested.
Abstract Titanium intermetallic materials are likely to play a significant role in the production... more Abstract Titanium intermetallic materials are likely to play a significant role in the production of future aeroengines. The paper details the machinabilty of a range of gamma titanium aluminide (γ-TiAl) intermetallic alloys when turning, grinding, HSM, drilling, EDM and ECM. Comprehensive literature review data is augmented with experimental results for turning, turn-milling and temperature measurement when high speed milling. Despite the ability to produce crack free surfaces when grinding and HSM, turning and drilling remain problematic. Turned surfaces are in general characterised by workpiece smearing, numerous arc shaped cracks, subsurface lamellae deformation and significant strain hardening, although the use of PCD tooling and ultrasonic assisted cutting has been shown to minimise these effects.
The International Journal of Advanced Manufacturing Technology, 2018
Following a brief review on the turning of nickel-based superalloys, the paper evaluates the mach... more Following a brief review on the turning of nickel-based superalloys, the paper evaluates the machinability and workpiece surface integrity of a powder metallurgy HIP-ed (PHIP) RR1000 alloy, involving two phases of turning experiments using TiN/Al 2 O 3 / Ti(C,N) coated carbide inserts. Based on a maximum flank wear criteria of 200 μm, tool life exceeded 40 min when operating at or below 100 m/min; however, Taylor tool life curves were extremely steep. At a feed rate of 0.08 mm/rev, workpiece surface roughness was~0.5 μm Ra. Tests at cutting speeds of 80 m/min or less with new tools showed the 'best/acceptable' surface integrity with no visible white layer or plucking and a maximum distorted layer of~6 μm deep. In contrast, the surfaces produced using worn tools at a cutting speed of 100 m/min showed a distorted layer of~20 μm deep with evidence of surface laps and plucking to a depth of~15 μm.
Five different coatings and two PCBN grades were evaluated when high speed turning Inconel 718. T... more Five different coatings and two PCBN grades were evaluated when high speed turning Inconel 718. Tool life was 40% higher when employing TiSiN coated over uncoated inserts at 200 m/min. When operating at 300-450 m/min however, coatings provided no appreciable benefit. Workpiece surface roughness varied between ~0.25-1.05 µm Ra while cutting forces were <300 N. Increased workpiece microhardness and microstructural deformation were apparent with worn inserts. Medium cBN content (65%) inserts generated near surface compressive residual stresses of approximately −440 MPa as opposed to values of −90 MPa (measured parallel to feed) when using low cBN content (50%) tools.
Where a licence is displayed above, please note the terms and conditions of the licence govern yo... more Where a licence is displayed above, please note the terms and conditions of the licence govern your use of this document. When citing, please reference the published version. Take down policy While the University of Birmingham exercises care and attention in making items available there are rare occasions when an item has been uploaded in error or has been deemed to be commercially or otherwise sensitive.
With stringent safety requirements, tight tolerances, and high-value components, it is imperative... more With stringent safety requirements, tight tolerances, and high-value components, it is imperative that the performance of a machine tool used in the aerospace industry is gauged prior to conducting any machining operations. Routine calibration gives confidence that a machine tool is running within specification, and will therefore be likely to produce good parts. Unfortunately, the full calibration of a machine tool is a lengthy process, making it impractical and costly to a business to run regularly – usually occurring no more than once per year. Instead, there is a necessity for machine tool health verification: a short routine that can be run regularly (i.e. once per shift, day, or week) to ensure a machine tool remains in good working order between calibrations. This research identified a number of key failure modes that can affect machine tools in aerospace manufacture and proposed solutions that could be utilised in testing for these. To fulfil this, a review of existing comme...
Machining-induced white layers and severely deformed layers are undesirable surface integrity fea... more Machining-induced white layers and severely deformed layers are undesirable surface integrity features which can be formed when machining high-strength aerospace alloys. An orthogonal milling process has been designed and performed to assess the impact of cutting speeds, tool wear, cutting edge radius and climb vs conventional milling on white layer formation and plastic strain distribution. The plastic deformation in the machined surface associated with the formation of white layers in Ti-6Al-4V has been quantified using micro-grids of different length scales printed using the electron beam lithography technique. It was found that white layers formed via the severe plastic deformation mechanism, at equivalent plastic strain values in excess of 1.2 and in regions of the cutting arc with the instantaneous chip thickness of less than the cutting-edge radius and ploughing and rubbing being the dominant mechanisms. The results indicated that the magnitude of the measured strains and the depth of plastically deformed material was greater at lower cutting speeds, during climb milling and when machining with a larger cutting edge radius and tool flank wear land.
In today's business environment, the trend towards more product variety and customization is unbr... more In today's business environment, the trend towards more product variety and customization is unbroken. Due to this development, the need of agile and reconfigurable production systems emerged to cope with various products and product families. To design and optimize production systems as well as to choose the optimal product matches, product analysis methods are needed. Indeed, most of the known methods aim to analyze a product or one product family on the physical level. Different product families, however, may differ largely in terms of the number and nature of components. This fact impedes an efficient comparison and choice of appropriate product family combinations for the production system. A new methodology is proposed to analyze existing products in view of their functional and physical architecture. The aim is to cluster these products in new assembly oriented product families for the optimization of existing assembly lines and the creation of future reconfigurable assembly systems. Based on Datum Flow Chain, the physical structure of the products is analyzed. Functional subassemblies are identified, and a functional analysis is performed. Moreover, a hybrid functional and physical architecture graph (HyFPAG) is the output which depicts the similarity between product families by providing design support to both, production system planners and product designers. An illustrative example of a nail-clipper is used to explain the proposed methodology. An industrial case study on two product families of steering columns of thyssenkrupp Presta France is then carried out to give a first industrial evaluation of the proposed approach.
Machining-induced white layers can affect the functional performance of engineered components, du... more Machining-induced white layers can affect the functional performance of engineered components, due to the resulting mechanical and microstructural properties. Destructive inspection methods such as cross-sectional microscopy are typically used to identify white layers, however, these methods are inherently costly and timeconsuming. It is, therefore, desirable to detect this anomalous surface feature using non-destructive methods which requires improved knowledge around the characteristics of white layers. The present paper reports on the characterization of white layers formed during machining of Ti-6Al-4V, to aid future development of a reliable non-destructive assessment method. The microstructure of the material in the white layer was found to have a basal-hexagonal close packed texture and there was no evidence of an phase transformation during white layer formation. The white layer has a highly refined grain structure with an increased nanohardness of up to 15% compared with the bulk material. It is proposed that white layers in Ti-6Al-4V are formed by continuous dynamic recrystallization driven by severe plastic deformation during machining. According to the measured micromechanical properties of the white layer, suitable non-destructive testing methods are suggested for the detection of this surface feature.
CIRP Journal of Manufacturing Science and Technology, 2018
The presence of machining-induced white layer in the near-surface of critical aeroengine alloys h... more The presence of machining-induced white layer in the near-surface of critical aeroengine alloys has a detrimental effect on the lifetime of a component. Present techniques for identifying and characterizing white layer, such as optical microscopy and hardness testing, whilst effective, are destructive, costly and time-consuming. Non-destructive testing methods may, therefore, offer improvements to the process of white layer detection. This paper discusses the formation mechanisms and the defining physical properties of machininginduced white layers before offering a comprehensive review of the current state-of-the-art in both destructive and non-destructive testing methods for detecting this anomalous surface feature.
Link to publication on Research at Birmingham portal General rights Unless a licence is specified... more Link to publication on Research at Birmingham portal General rights Unless a licence is specified above, all rights (including copyright and moral rights) in this document are retained by the authors and/or the copyright holders. The express permission of the copyright holder must be obtained for any use of this material other than for purposes permitted by law. • Users may freely distribute the URL that is used to identify this publication. • Users may download and/or print one copy of the publication from the University of Birmingham research portal for the purpose of private study or non-commercial research. • User may use extracts from the document in line with the concept of 'fair dealing' under the Copyright, Designs and Patents Act 1988 (?) • Users may not further distribute the material nor use it for the purposes of commercial gain. Where a licence is displayed above, please note the terms and conditions of the licence govern your use of this document. When citing, please reference the published version. Take down policy While the University of Birmingham exercises care and attention in making items available there are rare occasions when an item has been uploaded in error or has been deemed to be commercially or otherwise sensitive.
... 500 MPa. The effect of high speed milling parameters, including, flank wear (new tool/worn to... more ... 500 MPa. The effect of high speed milling parameters, including, flank wear (new tool/worn tool), cutting speed and angle-of-workpiece, on residual stress was further analysed using a Taguchi orthogonal array. This demonstrated ...
... Military work is lead by performance aspects and the requirement for engines with high thrust... more ... Military work is lead by performance aspects and the requirement for engines with high thrust-to-weight ratios, raised turbine temperatures and fewer compressor and turbine stages, all of which create ... In subsequent work by Zhang on 48-2-2 and also Mantle et al. ... Wheeler et al. ...
Experimental data is presented which compares the eect of grinding and high speed milling (HSM) o... more Experimental data is presented which compares the eect of grinding and high speed milling (HSM) on the fatigue strength of a gamma titanium aluminide intermetallic alloy. Results showed that HSM signi®cantly increased fatigue strength by as much as 200 MPa over polished samples. Measurement and analysis of workpiece subsurface microhardness and microstructure indicated that the high run-out values correlated to high hardness and plastic deformation of the near surface lamellae.
Machining data are presented for small diameter, profiled (fir tree root form), single layer/elec... more Machining data are presented for small diameter, profiled (fir tree root form), single layer/electroplated CBN (B46, B76 and 91) and diamond (D46) grinding wheels, when cutting Udimet 720. Spindles operating at 60,000 and 90,000rpm were employed, with a synthetic polyalphaolefine (PAO) oil based fluid in a down grinding mode on single sided specimens. Operating parameters were selected to reflect finishing conditions. Measured tool wear was lower for CBN grit as compared to diamond however workpiece roughness was lower with Ra approaching 0.75μm when using D46 wheels. Higher rotational speed produced lower grinding wheel wear. No workpiece burning was observed irrespective of grit type at the conditions tested.
Abstract Titanium intermetallic materials are likely to play a significant role in the production... more Abstract Titanium intermetallic materials are likely to play a significant role in the production of future aeroengines. The paper details the machinabilty of a range of gamma titanium aluminide (γ-TiAl) intermetallic alloys when turning, grinding, HSM, drilling, EDM and ECM. Comprehensive literature review data is augmented with experimental results for turning, turn-milling and temperature measurement when high speed milling. Despite the ability to produce crack free surfaces when grinding and HSM, turning and drilling remain problematic. Turned surfaces are in general characterised by workpiece smearing, numerous arc shaped cracks, subsurface lamellae deformation and significant strain hardening, although the use of PCD tooling and ultrasonic assisted cutting has been shown to minimise these effects.
The International Journal of Advanced Manufacturing Technology, 2018
Following a brief review on the turning of nickel-based superalloys, the paper evaluates the mach... more Following a brief review on the turning of nickel-based superalloys, the paper evaluates the machinability and workpiece surface integrity of a powder metallurgy HIP-ed (PHIP) RR1000 alloy, involving two phases of turning experiments using TiN/Al 2 O 3 / Ti(C,N) coated carbide inserts. Based on a maximum flank wear criteria of 200 μm, tool life exceeded 40 min when operating at or below 100 m/min; however, Taylor tool life curves were extremely steep. At a feed rate of 0.08 mm/rev, workpiece surface roughness was~0.5 μm Ra. Tests at cutting speeds of 80 m/min or less with new tools showed the 'best/acceptable' surface integrity with no visible white layer or plucking and a maximum distorted layer of~6 μm deep. In contrast, the surfaces produced using worn tools at a cutting speed of 100 m/min showed a distorted layer of~20 μm deep with evidence of surface laps and plucking to a depth of~15 μm.
Five different coatings and two PCBN grades were evaluated when high speed turning Inconel 718. T... more Five different coatings and two PCBN grades were evaluated when high speed turning Inconel 718. Tool life was 40% higher when employing TiSiN coated over uncoated inserts at 200 m/min. When operating at 300-450 m/min however, coatings provided no appreciable benefit. Workpiece surface roughness varied between ~0.25-1.05 µm Ra while cutting forces were <300 N. Increased workpiece microhardness and microstructural deformation were apparent with worn inserts. Medium cBN content (65%) inserts generated near surface compressive residual stresses of approximately −440 MPa as opposed to values of −90 MPa (measured parallel to feed) when using low cBN content (50%) tools.
Where a licence is displayed above, please note the terms and conditions of the licence govern yo... more Where a licence is displayed above, please note the terms and conditions of the licence govern your use of this document. When citing, please reference the published version. Take down policy While the University of Birmingham exercises care and attention in making items available there are rare occasions when an item has been uploaded in error or has been deemed to be commercially or otherwise sensitive.
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Papers by Andrew Mantle