Feed Marks Research Articles

Surface topography analysis and cutting parameters optimization for peripheral milling titanium alloy Ti–6Al–4V

This paper presents the effect of cutting parameters (cutting speed, feed rate and radial depth of cut) on surface topography in peripheral milling of titanium alloy Ti–6Al–4V. Peripheral milling experiments based on the Taguchi method have been conducted on Ti–6Al–4V to characterize surface topographies by various milling conditions. Surface analysis techniques including surface defects, multiple linear regression analysis of surface parameters and auto-correlation analysis of the surface profile, were implemented to characterize the machined surface topography. The experimental results have shown that the main forms of surface defect in peripheral milling of Ti–6Al–4V are feed marks, scratch marks, adhered material particles, etc. The high quality of the machined surface can be obtained in the combined conditions with high cutting speed, low feed and small radial depth of cut. Auto-correlation analysis is used to describe the spatial relation dependence of the surface topography, the direction and periodicity of the surface texture. Increasing cutting speed is helpful to reduce the random components in the auto-correlation spectra of the machined surfaces. However, increasing feed rate has the opposite effect. Radial depth of cut has no significant influence on auto-correlation spectra in finish milling.

Investigation of deposit formation in direct-injection spark-ignition engine powered on syngas

A direct-injection spark-ignition engine was investigated for deposit formation after running on syngas. The study was part of an initiative to substitute fossil derived gaseous fuels with syngas. The fuel injector and spark plug were periodically inspected during the shutdown and the preliminary inspection indicated traces of deposits. As a result, the cylinder head was dismantled and inspected thoroughly after the run. The surface morphology was characterized by FESEM and its elemental contents were evaluated by EDX. Among the components, the spark plug was found to be best suitable for scanning in FESEM and EDX. Tests were conducted on the sides with and without deposit of the spark plug. The results from both sides were compared. No feed marks were formed even at higher magnification at the clean side. However, the side with deposit of the spark plug shows a spongy texture foreign material. Besides, the colour and morphology was different at different locations. Chemical composition was evaluated on atomic and weight percentage. The deposit was found to be iron oxide produced from the decomposition of iron pentacarbonyl contaminant from the storage tank as the result of carbon monoxide reaction with metallic wall of the tank at high pressure storage.

English

This paper discusses the quality of surface finish when threading titanium-based alloy under dry condition. The quality of surface finish was studied at various cutting parameters and at the two extreme stages of the machining process, i.e. at the beginning and end of the process. The objective is to evaluate the effect of a worn-out tool on the quality of surface finish. PVD-coated carbide tools were used in this study. Experiments were conducted at two cutting speeds, 35 and 55 m/min, two depths of cut, 0.2 and 0.25 mm, and a constant pitch of 2.0 mm. The tool wear and the quality of surface finish were inspected visually by microscope. The tool’s flank wear was measured gradually and machining was stopped when the flank wear reached the rejection criterion of0.3 mm. The microstructure beneath the machined surface was also evaluated. It was found that, at the beginning of machining, there was only a feed mark on the surface finish. When the machining was prolonged until the tools reached the rejection criterion, a bad surface finish was produced. Metal debris, surface cavities and a boundary crack were observed. Results show that machining with a worn-out tool can cause microstructure alteration beneath the machined surface. The selection of cutting parameters and monitoring of tool wear are crucial in order to obtain a good surface finish. Characterization of the surface finish with respect to the threading process under a dry condition would ultimately help in the development of suitable parameters for machining titanium-based alloys.

Surface integrity characterization in high-speed dry end milling of Ti-6Al-4V titanium alloy

Surface integrity is a key property in the functional performance of machined parts and assembled engineering components. In this study, the effects of cutting conditions and tool wear on the surface integrity of Ti-6Al-4V titanium alloy after high-speed dry end milling were investigated. Different cutting speeds (100–300 m/min) and feeds (0.03 and 0.06 mm/tooth) as well as TiAlN + TiN physical vapor deposition (PVD)-coated carbide tool were employed during the machining trials. Surface roughness value and sub-surface microhardness of the machined surfaces were measured, and the corresponding alterations beneath the surface were characterized through electron microscopy. Results showed that surface roughness values at different cutting speeds directly depends on the tool conditions. The use of a new tool contributed to a higher surface quality of 185 nm compared to 320 nm for the used tool at the highest investigated cutting speed. It was found that operating the end milling with the new tool at a higher feed rate significantly decreased the surface roughness of the machined surface from 415 to 225 nm at a lower cutting speed. Feed marks and material redeposition defects were detected on the surface, while plastic deformation was observed in the sub-surface of the machined surface. Microhardness measurement revealed that no significant alterations occurred at the sub-surface when lower cutting speed and feed were employed. Higher cutting speed and feed rate enhanced the sub-surface alteration and resulted in considerable plastic deformation. Microscopic observations further highlighted this behavior.

Surface morphology and microcrack formation for 7050-T7451 aluminum alloy in high speed milling

The study in this paper focuses on surface morphology and crack formation of 7050-T7451 aluminum alloy in high-speed milling, from 3000 to 5000 m/min. The surface roughness of machined workpiece was investigated with optical profiler; minimum R a and R q value were obtained at the cutting speed of 5000 m/min. Defects such as smeared material, metal debris, and feed marks on workpiece surface were observed with scanning electron microscope. One kind of edge-oxidized feed mark was found on surface. Width of it was measured and two hypotheses were introduced to interpret this phenomenon. Based on the hypothesis, the workpiece surface was determined to be formed at cut-off process. Two kinds of microcracks were observed on Al7Cu2Fe and Mg2Si phase. Those cracks showed different orientations, and this was helpful for interpreting the formation of microcracks in high-speed machining. The heat imposed to surface was connected with cracks on different phases. The results provided a complete view of surface morphology generation and microcrack-formation mechanism in high-speed cutting process. The two aspects of this research were helpful for controlling the integrity of surface and prolong service life of workpiece.

Ingestion of plastics at sea: does debris size really matter?

Most of our knowledge on plastic ingestion by zooplankton comes from experiments exposing invertebrates to plastic particles smaller than their feeding apparatus. By examining millimetre-sized marine plastics using a scanning electron microscope, we putatively identified some surface textures as feeding marks produced by invertebrates grazing upon the plastic biofilm. We observed sub-parallel linear scrapes with 5-14 μm spacing, which is similar to typical distances between teeth of the mandibular gnathobases of copepods. We also observed peculiar rounded marks close to an unidentified marine worm. Small portions of the plastic particles were apparently removed, and perhaps ingested, during these putative grazing activities. Thus, we suggest that (1) plastic biofouling induces plastic ingestion, and (2) plastic pieces must not necessarily be smaller than the organism for a feeding interaction to occur. Experiments exposing invertebrates to millimeter-sized plastics may support these suggestions.

Clustered parrotfish feeding scars trigger partial coral mortality of massive Porites colonies on the inshore Great Barrier Reef

Coral predation by parrotfishes can cause damage to coral colonies, but research into the dynamics of their feeding scars on Indo-Pacific corals is limited. We monitored feeding scars of the parrotfish Chlorurus microrhinos on massive Porites colonies at Orpheus Island (inshore Great Barrier Reef) over 4 months. Of the 30 marks monitored, 11 were single feeding scars, which all healed completely. The remaining 19 feeding marks consisted of clusters of scars. Eight began to recover, while 11 increased in size by 1,576 ± 252 % (mean ± SE). A logistic regression predicted that a single feeding scar on a Porites colony had a 97 % probability of healing; however, where more than three feeding scars were present, this dropped below 50 %. As excavating parrotfishes in the Indo-Pacific often take multiple focused bites, they may have a significant impact on the growth and mortality of massive Porites colonies at Orpheus Island.

Comparative study of surface integrity aspects of Incoloy 825 during machining with uncoated and CVD multilayer coated inserts

One of the major concerns related to machining of Ni-based super alloy is surface integrity since it directly affects the performance of the machined component during its intended application. In the current study, the influence of cutting speed (51, 84 and 124m/min) and CVD multilayer tool coating (TiN/TiCN/Al2O3/ZrCN) on various aspects of surface integrity such as surface roughness, crystal structure and microstructure of the surface and sub-surface region, thickness of white layer and work hardening tendency have been investigated during dry turning of Incoloy 825. Particular emphasis has been given to understand the mechanism of formation of modified surface layer and the associated process of dynamic recrystallization. The study indicated coated tool resulted in better surface finish compared to that obtained with uncoated tool only at high cutting speed. Various macro features of machined surface included feed mark, material smearing, surface ploughing, re-deposited materials and chip debris. Transformation of crystallographic phase of the machined surface could not be detected compared to that of bulk material. Increase in cutting speed caused gradual refinement of grains, and increased white layer thickness. Coated tool, on the other hand, resulted in the generation of large number of nucleation sites and consequently finer grains at high cutting speed, whereas the uncoated tool promoted growth of sharply defined recrystallized grains. The coated tool prevented the formation of white layer at low and medium cutting speed and also decreased work hardening tendency of Incoloy 825 when compared with that of uncoated tool.

Epichloë clarkii - a new graminicolous species for Poland

<i>Epichloë clarkii</i> White, described in 1993 from England has been noted from Wielkopolski National Park in Poland. The eggs and feed marks of hyperparasitic fly, <i>Botanophila</i> sp. have been found on teleomorph stromata of <i>E. clarkii</i>.

English

This paper presents an experimental study of surface integrity in end milling of Hastelloy C-2000. The experiment was carried out using two different cutting inserts under wet conditions – namely physical vapor deposition coated carbide with TiAlN and uncoated carbide. Design of experiment was implemented with a Box-Behnken design. The surface integrity of the workpiece was analyzed through scanning electron microscopy (SEM) and chemical element changes were inspected by an energy dispersive X-ray (EDX) test. The surface integrity of Hastelloy C-2000 was better when machining with coated carbide compared to uncoated carbide cutting inserts, mainly because the coating layer of coated carbide acted as a protecting layer to the cutting tool insert. Surface defects such as feed marks, surface tearing, plucking, cracking and adhered chips were found during the machining process. The chemical element changes happened due to the adhesion and diffusion mechanisms which were identified using SEM and EDX.

English

Metal matrix composite (MMC) is a combination of two or more materials in a metal matrix, and is being widely used nowadays due to its excellent properties. This paper presents the surface integrity of LM6 aluminum MMC when machined with two different cutting tools; high speed steel (HSS) and uncoated carbide. The experiments were carried out with a constant cutting speed, feed rate and axial depth of cut, but differ in the radial depth of cut under dry cutting conditions. Results indicated that machining LM6 with uncoated carbide cutting tools provides a lower surface roughness and fine surface profile compared to HSS cutting tools, due to its edge stability. A lower radial depth of cut produced a fine surface finish and vice versa. Most of the machined surface was dominated by the feed mark effect due to path overlap from the cutting tool. This study is expected to provide a database of suitable cutting tools and cutting parameters for machining MMC based materials.

Review of the Machining Difficulties of Nickel-Titanium Based Shape Memory Alloys

The purpose of this study is to identify machining difficulties of nickel-titanium based shape memory alloys. Nickel-titanium (Nitinol) is one the widely used shape memory material which is applied in many products in the aerospace, medical, and biomedical fields. NiTi alloy cannot be machined easily because of high tool wear, high cutting force, huge hardness and surface defects are made many problems into their machining. Investigation in micron precision shows plenty surface defects in machining process, something like debris of microchips, feed marks, tearing surface, deformed grains, material cracking and chip layer formation which consists the main problem in the machining of shape memory alloys. Moreover, these defects can be reduced or eliminated by changing the cutting parameters such as: feed rate, cutting speed and cutting depth so that, machining of nickel-titanium alloys would be improved.

Effect of High Speed Dry End Milling on Surface Roughness and Cutting Forces of Ti-6Al-4V ELI

The surface quality generated when high speed dry end milling (HSDEM) Ti-6Al-4V-ELI titanium alloy with coated and uncoated carbide tools were investigated. Evaluation was conducted using TiAlN+TiN coated and uncoated cemented carbide tools under different high cutting speeds and feed rates conditions. Surface roughness and cutting forces were measured when using new tools. The milled surface quality and corresponding alteration were characterized through electron microscopy. Within the investigated conditions high quality surface finish was obtained on the machined surface. Increasing cutting speed from 200 to 300 m/min during the process improved the surface finished particularly under lower feed rates. In term of generated surface quality, uncoated H25 grade carbide tools out performed coated F40M grade specifically at the higher cutting conditions. The main damages observed after HSDEM on the surface for all machining conditions contain redeposited materials, feed marks, and tool edge marks. Under both tested feed rates the resultant cutting force decreased by increasing the cutting speeds and uncoated carbide tools provide the lower cutting forces compared to coated types.

Study on the Cutting Forces and Surface Integrity in High Speed Milling of Aluminum-Lithium Alloy

Aimed at the uncertain and unpredictable cutting forces and surface integrity of new lightweight aeronautical structural material aluminum-lithium alloy after high speed milling, an experimental study of cutting forces and surface integrity including surface roughness, surface morphology, micro-crack, metallurgical structure and surface stress is presented by means of rough meter, SEM, X-ray stress analyzer etc. The experimental results show that cutting forces increase linearly as the feed per tooth increases. As the cutting speed increases, the cutting forces increase firstly and then decrease; the surface roughness increases as the feed per tooth increases. However, the influence of cutting speed on surface roughness is not obvious; The surface of aluminum-lithium alloy after milling contains factors such as feed marks, micro-pits, burrs caused by cutting vibration; In addition, no micro-cracks of surfaces after milling was detected and the surface stress amplitude is small.

Analysis of the machining characteristics in reaming AlSi12 alloy with PCD reamer

Machining characteristics were studied for the reaming AlSi12 alloy using six flutes polycrystalline diamond reamer on DMG DMU 50 linear five-axis CNC machine. The output measures for this experiment comprise of cutting torque, cutting thrust, hole diameter, hole cylindricity, and workpiece surface finishing. Cutting forces were in real time monitored by Kistler Dynamometer during the experiments. Hole diameter, hole cylindricity, and surface finishing (surface roughness and surface integrity) of the machined surfaces were measured after machining. It is indicated that the cutting force of thrust and torque decreased with increase of cutting speed and decrease of cutting feed. High accuracy of hole was achieved because the hole measurements satisfied the standard deviation. Hole diameters were within tighter tolerance value of 330 0.025, and cylindricalities varied in the range from 0.002 to 0.014 um (less than 0.02 um). As to surface finishing, high surface performance could be obtained by eliminating surface defects on initial hole such as cavities and voids after subsequent finishing operating of reaming. However, the reamed surface damages of AlSi112 alloy under inapposite cutting conditions were involved with re-deposited work material (chip), surface grooves and notch, feed marks, surface shrinkage cavities and porosities, metal debris, and micro-pits. Moreover, surface roughness improved with an increase in the cutting speed from 2,000 to 6,000 rpm, but it deteriorated evidently when the cutting speed increased from 6,000 to 10,000 rpm. Cutting speed of 6,000 rpm and cutting feed of 3,000 mm/min were the recommendable cutting parameters to ream AlSi12 alloy because best hole quality could be produced in comparison of other cutting parameters.

SURFACE INTEGRITY OF HIGH-SPEED FACE MILLED Ti-6Al-4V ALLOY WITH PCD TOOLS

This study is focused on the machined surface integrity of Ti-6Al-4V alloy using polycrystalline diamond (PCD) tools under wet milling condition. The surface integrity in terms of surface roughness, surface topography, microhardness, microstructure, and metallurgical alternations is investigated. The observations and conclusions are primarily focused on the effect of cutting speed (250–2,000 m/min) on the surface and subsurface of the machined Ti-6Al-4V. Experimental results show that machined surface integrity of Ti-6Al-4V alloy is sensitive to the variation of cutting speeds. Obvious machining (feed) marks can be found on the machined surfaces. Micro hardness examinations showed 5–20% hardening of the top machined surfaces than the bulk material. The analyses of microstructure and metallurgical alternations reveal that slight subsurface microstructure alteration such as plastic deformation on the subsurface and no phase transformation were observed. The evolution of crystallographic texture induced by the intense plastic deformation of the machined surface should be responsible for the modifications of the peak intensity radios in XRD patterns as well as higher peak broadening crystal structures.

Presentation of a novel cutting technology for precision machining of hardened, rotationally symmetric parts

In this paper a new cutting technology similar to hard turning is presented to cut rotationally symmetric parts made of hardened materials. This novel technology, which is named rotational turning, is based on a combination of hard turning and circular milling. An analytical model is developed to describe the engagement parameters between tool and workpiece. It is shown by the model, that the virtual tool corner radius in rotational turning, which takes effect during the cutting process, is more than 50 times larger than in state of the art hard turning. Due to this, feed marks, which are common in turning, can be reduced to a level, where they are not measurable anymore. It can be shown in experiments, that the minimum achievable surface roughness is therefore not limited by the feed rate anymore, like in turning processes usual, but by other effects like the waviness of the cutting edge.

Feeding activity by the blenny Exallias brevis causes multifocal bleaching in corals: Comment on Zvuloni et al. (2011)

MEPS Marine Ecology Progress Series Contact the journal Facebook Twitter RSS Mailing List Subscribe to our mailing list via Mailchimp HomeLatest VolumeAbout the JournalEditorsTheme Sections MEPS 463:297-299 (2012) - DOI: https://doi.org/10.3354/meps10002 COMMENT Feeding activity by the blenny Exallias brevis causes multifocal bleaching in corals: Comment on Zvuloni et al. (2011) Bruce A. Carlson* Georgia Aquarium, 225 Baker Street, Atlanta, Georgia 30313, USA *Email: bcarlson@georgiaaquarium.org ABSTRACT: The shortbodied blenny Exallias brevis is an obligate corallivore. Studies on Hawaiian reefs and casual observations on other Pacific reefs reveal that E. brevis feeds on a wide variety of scleractinian corals, including the hydrocoral Millepora spp. This blenny produces distinctive circular feeding marks of ca. 2 cm2 on corals; the marks can persist for 50 d or more. E. brevis is indigenous to the Red Sea and may be responsible for the multifocal bleaching syndrome in Red Sea Millepora dichotoma described by Zvuloni et al. (2011; Mar Ecol Prog Ser 441:25−32). KEY WORDS: Exallias brevis · Shortbodied blenny · Corallivore · Millepora spp. · Multifocal bleaching · Red Sea Full text in pdf format PreviousNextCite this article as: Carlson BA (2012) Feeding activity by the blenny Exallias brevis causes multifocal bleaching in corals: Comment on Zvuloni et al. (2011). Mar Ecol Prog Ser 463:297-299. https://doi.org/10.3354/meps10002 Export citation RSS - Facebook - Tweet - linkedIn Cited by Published in MEPS Vol. 463. Online publication date: August 30, 2012 Print ISSN: 0171-8630; Online ISSN: 1616-1599 Copyright © 2012 Inter-Research.

Revision of Early Cretaceous angiosperm remains from the Rajmahal Basin, India, with notes on the palaeoecology of the Pentoxylon plant

In India, potential sources of angiosperm macrofossils are the intertrappean cherts of Rajmahal Hills, palynologically and radiometrically dated as Barremian–Aptian. However, our revision of the previously reported flower-like and fruit-like fossils from the Rajmahal Formation does not confirm their angiosperm affinities. Instead they are related to bennettitalean and pentoxylean gymnosperms. At the same time, the underground storage organs and supposed feeding marks on Carnoconites seeds revealed in the course of this study suggest angiosperm-like habits in the Indian Pentoxylon plant.

Identification of Surface Generation Mechanisms Based on Process Feed-Back and Decomposition of Feed Marks

This paper proposes a novel integrated approach to the prediction of surface generation mechanisms which takes into account both cutting process outputs and distortions of the individual feed marks in comparison to an ideal kinematical model. For this task, the recorded surface roughness profile was decomposed using special algorithms. The mechanisms of real surface generation considered include the plastic side flow and spring back effects, the cutting edge sharpness and its wear, and dynamic interactions between the tool and the workpiece. The computation procedure was verified for different workpiece materials in conjunction with uncoated and coated, sharp and worn, tools.