Chip Loading Research Articles

Influence of bond thermal and mechanical properties on the additively manufactured grinding wheels performance: Mechanical, wear, surface integrity, and topography analysis

It is always a great challenge to fabricate customized grinding wheels using diverse bonding materials to determine their impacts on the cutting ability and grinding performance. Additive Manufacturing methods offer tremendous advantages for customized and prototype production to reduce the cost as well as increase speed to market. This work aims to extend the grinding operation knowledge by examining acrylate base resin bonds with different mechanical and thermal characteristics to print the grinding wheels. Extensive experiments are conducted to investigate their performance in metal grinding, with hardness ranging from soft to super hard. A remarkable improvement in grinding performance has been established by using high-temperature resistance bond material, which was more prominent in the case of aluminium and hardened steel. It was discovered that utilizing the bond material with a higher mechanical and thermal characteristic could provide high grain retention under elevated temperatures, which participated in less grinding force (up to 58 % and 18 % in the case of soft and hard metals, respectively). Employing bond material with improved mechanical and thermal properties to fabricate grinding wheels significantly prolonged the tool life, for example, by up to 80 % for hardened steel at maximum, along with promoting dimensional accuracy. Nevertheless, however, using high-temperature resistance resin brought slight improvement in tool life for the hard metals grinding due to the intensely aggressive grinding condition, which could not be largely compensated by using modified resin. The surface roughness of the ground part represented considerable improvements through using high-temperature resistance resin by representing 33 % and 30 % roughness values reduction for Al and hard metal, respectively, compared to those ground with lower temperature resistance resin. Moreover, the ground surface's microhardness examination indicated meaningful surface microstructure change by applying different grinding parameters and bond material types. Furthermore, the microtopography of the grinding wheels before and after the grinding operation revealed that employing the higher temperature resistance resin could bring about notably less chip loading and grain loss.

Chip loading on electroplated diamond wheels in trimming process for CFRPs and effects by in-process laser dressing

Chip loading on electroplated diamond wheels in trimming process for CFRPs and effects by in-process laser dressing

Progress in grinding performance by additive manufacturing of grinding wheels integrated with internal venturi cooling channels and surface slots

Among the most promising features of additive manufacturing are tool or form-free manufacturing and the ability to create intricate geometries that are difficult or even impossible to fabricate with traditional methods. These advantages can be employed to produce enhanced grinding tools. Efficient coolant fluid delivery into the cutting zone of the grinding operation has been a challenging problem since high frictional contact in the arc zone deteriorates the resin bond and lessens the grinding performance. This research study was dedicated to assessing the influence of internal cooling along with surface structures on the grinding performance of resin-bonded grinding wheels fabricated via additive manufacturing. This research introduced a novel structure that benefits from internal venturi shape cooling channels to provide exceptional fluid velocity in the tool and workpiece interaction zone. The grinding wheels have been produced employing vat photopolymerization. Grinding experiments with and without internal cooling were conducted on an aluminium plate to study the impact of introduced structures on the main aspects of grinding performance, such as cutting forces, surface roughness, tool wear, and dimensional accuracy. Two different grinding scenarios comprising shallow (10 μm depth of cut) and deep grinding (100 μm depth of cut) were carried out to reveal the influence of the material removal rate on the grinding experiments. The measured grinding forces revealed that integrating internal cooling channels and surface slots in a grinding tool could significantly reduce the grinding forces, which was more pronounced in the case of using venturi channels. Measured tool wear and dimensional accuracy together with calculated grinding ratio revealed that using cooling channels could participate in a notable increase in tool life and material removal ability, especially for venturi channels, due to improved cutting conditions, by which higher dimensional accuracy was obtained as well for the ground parts. Besides, it was discovered that the cooling channels could improve the surface quality of the ground part, which was less noticeable with the venturi channel grinding wheel. Furthermore, the optical and confocal microscopy detection confirmed that internal cooling channels could reduce chip loading on the grinding wheel surface, decrease the required number of dressing intervals, and cause effective promotion of tool life.

Machine Learning-Based Wheel Monitoring for Sapphire Wafers

The thinning of sapphire wafers is a key process that affects the quality of optoelectronic devices. In the grinding process for sapphire, a hard and brittle material, the grade and surface conditions (wearing and chip loading) of the grinding wheel are the key to continuous processing and reduction of defects. In industry, a common approach is to assume the possible causes of defects by observing the spindle current during the grinding process and the finished product after processing. Thus far, there has been no effective method to quantify the grade and no real-time monitoring technology for grinding wheels. This research proposes a wheel monitoring system that utilizes acoustic emission (AE) signals and radial/axial vibration signals to extract characteristic parameters via popular machine learning classification algorithms (k-NN, ANN, and SVM) in order to identify the signal and characteristic parameters of the wheel during the grinding process. The experimental results show that the AE signal identification accuracy of the grade is excellent, at 99%. The vibration signal of the wheel surface condition during the grinding process is significant as well, yielding an identification accuracy of 91%. The extracted signal characteristics in this research not only quantify the state of the grinding wheel, but also facilitate a wheel monitoring system based on the identification technology. The proposed method for grinding wheel processing status monitoring can be used to establish an automated intelligent grinding system.

Tellurium-assisted and space-confined growth of graphene single crystals

Low-temperature synthesis of large-area graphene films by chemical vapor deposition (CVD) method has attracted extensive research interests owing to their extraordinary potential applications. Current reports on the low-temperature graphene growth usually involve catalytic metal substrates, which exceedingly impedes the direct use of graphene in nanoelectronic fabrications. In this project, we design a space-confined growth chamber utilizing two SiO2/Si chips. The bottom chip loading pre-transferred graphene flakes accommodates the growth of second monolayer graphene, with a tellurium (Te) vapor assisted growth process. Polymethylmethacrylate (PMMA) residues introduced from the transferred graphene substrate is employed as the solid carbon source. Further, the numerical simulation results prove that the high concentration of active carbons in the confined space plays a vital role in this growth process. Density functional theory (DFT) calculations reveal that, Te atoms prefer to bond with the edge carbons of small graphene flakes and serve as an effective catalyst, which helps to grow small graphene flakes by reducing their energy of formation. The successful growth can provide the high-quality monolayer graphene grains at the low temperature (∼350 °C). This facile strategy promises the mass production of graphene at mild conditions and low costs, which contributes to the green chemistry in future.

The effects of mechanically loaded osteocytes and inflammation on bone remodeling in a bisphosphonate-induced environment.

Bisphosphonate-related osteonecrosis of the jaw is a disease appearing after tooth removal in patients undergoing bisphosphonate treatment for metastasizing cancers and osteoporosis. The complexity of the condition requires a multicellular model to address the net effects of two key risk factors: mechanical trauma (pathologic overload) and inflammation. In this work, a system comprised of a polydimethylsiloxane chip and mechanical loading device is used to expose bisphosphonate-treated osteocytes to mechanical trauma. Specifically, osteocytes are treated with the potent nitrogen-containing bisphosphonate, zoledronic acid, and exposed to short-term pathologic overload via substrate stretch. During bone remodeling, osteocyte apoptosis plays a role in attracting pre-osteoclasts to sites of damage; as such, lactate dehydrogenase activity, cell death and protein expression are evaluated as functions of load. Additionally, the effects of osteocyte soluble factors on osteoclast and osteoblast functional activity are quantified. Osteoclast activity and bone resorption are quantified in the presence and absence of inflammatory components, lipopolysaccharide and interferon gamma. Results suggest that inflammation associated with bacterial infection may hinder bone resorption by osteoclasts. In addition, osteocytes may respond to overload by altering expression of soluble signals that act on osteoblasts to attenuate bone formation. These findings give insight into the multicellular interactions implicated in bisphosphonate-related osteonecrosis of the jaw.

Development of an AmpliSeqTM Panel for Next-Generation Sequencing of a Set of Genetic Predictors of Persisting Pain

Background: Many gene variants modulate the individual perception of pain and possibly also its persistence. The limited selection of single functional variants is increasingly being replaced by analyses of the full coding and regulatory sequences of pain-relevant genes accessible by means of next generation sequencing (NGS).Methods: An NGS panel was created for a set of 77 human genes selected following different lines of evidence supporting their role in persisting pain. To address the role of these candidate genes, we established a sequencing assay based on a custom AmpliSeqTM panel to assess the exomic sequences in 72 subjects of Caucasian ethnicity. To identify the systems biology of the genes, the biological functions associated with these genes were assessed by means of a computational over-representation analysis.Results: Sequencing generated a median of 2.85 ⋅ 106 reads per run with a mean depth close to 200 reads, mean read length of 205 called bases and an average chip loading of 71%. A total of 3,185 genetic variants were called. A computational functional genomics analysis indicated that the proposed NGS gene panel covers biological processes identified previously as characterizing the functional genomics of persisting pain.Conclusion: Results of the NGS assay suggested that the produced nucleotide sequences are comparable to those earned with the classical Sanger sequencing technique. The assay is applicable for small to large-scale experimental setups to target the accessing of information about any nucleotide within the addressed genes in a study cohort.

P093 Next generation sequencing – evolution to a workflow model for exclusive primary HLA typing of hematopoietic stem cell and solid organ transplantation

Aim Our lab has established the NXType™ kit on the Ion-Chef and Ion-S5 workflow for high resolution HLA typing. This work was aimed to evaluate the analytical performance of the method for accuracy, precision, sensitivity, specificity, reportable range, repeatability, and reproducibility. We also determined optimal run size and workflow within the lab to strike a balance between suitable number of reads per locus and number of samples to avoid low coverage and dropouts. Using NGS as primary typing method for hematopoietic stem cell (HSC) and the solid organ (SO) programs was assessed. Methods Class I and HLA Class II were amplified with NXType™ or ALLType™ primer sets. Automated template preparation and chip loading were performed in the Ion Chef™ system and run on Ion S5™. Data was analyzed with TypeStream™ v1.1.0.11 and TypeStream™ Visual NGS Analysis Software. Results We found that the optimal run size was a minimum of 24 samples, a 3-fold increase of previous capacity. To maximize the use of chip space the number of samples/run was increased with confirmatory solid organ typings. We determined that running 24 samples with SSOP or NGS required similar manpower and instrument time. Although lab work was less with SSOP, analysis time and effort was greater than with NGS. After two years of experience with NGS HLA typing (∼1500 samples), we considered using NGS as the primary typing method for the HSC and the solid organ programs. Our historical data showed only 2 cases where NGS gave non-concordant results with SSOP or SSP. However, these samples were flagged by the software and both had associations that were red-flagged during analysis. The repeat rate for SSOP was 2.8% while for NGS was 0.3%. All NGS repeats were technical failures and not ambiguity resolution. We evaluated the ALLtype kit, which includes DQA1 necessary for solid organ initial typing, and a liquid handler for automation of library preparation. In addition, we implemented the TypeStream Visual (TSV) analysis software that includes serological equivalents. Conclusions We confirmed that NGS is a robust methodology for HLA typing. It provides results first time is run, reducing reflex testing. Combining automation with ALLType™ kit and TSV software, the analysis will be used as the primary method and SSOP as a reflex method for HSC and SO.

P157 Evaluation of one lambda NXType™ next generation sequencing

Aim To evaluate the NXType™ (One Lambda, Inc.) HLA next generation sequencing (NGS) for accuracy and precision and to evaluate the accompanying Typestream™ analysis software. In addition, to asses NXType™ in terms of workflow, labor and the required technical skills. Methods Thirty-two genomic DNA samples that were previously typed by LABType Sequence Specific Oligonucleotide (SSO) (One Lambda, Inc.) including 11 samples typed by Sequence Specific primer (SSP) (Invitrogen, Inc.) were used in this study. These included 5 proficiency testing (PT) samples. The NXType™ NGS workflow protocol was followed strictly. The amplification was carried out using long range multiplex primer mixes for HLA class I and class II genes followed by library preparation, isothermal amplification, chip loading and sequencing. The sequencing data was analyzed by Typestream™ software. Repeat testing and analysis was performed on the 32 samples over two weeks period with PT samples repeated 3 times. Results NXType™ NGS typing showed 100% concordance and reproducibility with SSO/SSP for all HLA A, B, C, DRB1, DRB345, DQB1 & DPB1 loci. In addition NXType™ resolved common ambiguities in class I loci often seen with the SSP method. For HLA Class II, ambiguities were detected in 5 samples. These were DRB1∗09:01/21, DPB1∗13:01/107:01, DPB1∗17:01/124:01, DPB1∗104:01/131:01 and DPB1∗13:01/107:01/131:01. The entire run of the 32 samples can be completed from amplification to reporting within 5 routine working days. The Typestream™ software is user friendly and provides detailed information about chip loading, clonality, usable reads, quality of library, exon coverage and allele balance. Conclusions We concluded that the NXType™ NGS typing is accurate and reliable. However, it is labor intensive. NXType™ purification, size selection and isothermal amplification steps are very sensitive and directly impact the quality of NGS data. Automation of NXType™ workflow is needed to reduce technical errors, insure consistency and increase NGS data quality.

P044 One year experience with HLA typing by next generation sequencing (NGS), achievements and challenges

Aim After a year of implementing HLA typing by NGS, we present our most relevant achievements and challenges. Methods Class I (full HLA-A, -B, and -C genes) and HLA Class II (Exon 2 thru intron 3 of HLA-DR and HLA-DQ, and Exon 2 thru 3’UTR of HLA-DP) amplified with NXType™ Class I and Class II primer sets. Automated template preparation and chip loading were performed in the Ion Chef™ system and run on Ion S5™. Data was analyzed with TypeStream™ v1.1.0.11 software. Results Having typed over 1000 samples by NGS, with 50% from bone marrow programs and 50% from solid organ programs, our workflow has changed significantly: Threefold increase in capacity with simultaneous decrease in turn-around-time (TAT, on average 10 days) for high resolution typing. Our current capacity is up to 96 HLA typings in 3–4 days vs. minimum of 16 days for the same volume with SBT by Sanger. Resolution of most ambiguities (98.7%), minimizing the need for reflex testing.Repetitions due to technical failures and ambiguities decreased from 4.3% with SBT-Sanger to 0.3% with NGS. In spite of positive workflow changes, there remain challenges: Automation of library preparation has not been implemented.No merging of library preparation reagents into a single kit.Smaller runs increase the number of reads, leading to artifacts and high background generated by the software, interfering with analysis and limiting flexibility for STAT sample processing.For solid organ typings, generating high resolution results while reporting Serological Equivalents for UNOS, poses logistical difficulties.TypeStreamTM software not interfaced with Fusion, requiring continuous need to run SSOP for DSA analysis.Unresolved ambiguities (1.3%), due to incomplete exon coverage and phase ambiguities. Resolution may be obtained by increasing gene coverage, length of reads and with additional testing methods. Conclusions We have confirmed that NGS is both a suitable and faster method to obtain high resolution HLA typing. We have seen a significant decrease in TAT along with a significant cost savings due to fewer repetitions, fewer reagents, and most significantly, reduced time from our most valuable asset, our technologists.

A Targeted High-Throughput Next-Generation Sequencing Panel for Clinical Screening of Mutations, Gene Amplifications, and Fusions in Solid Tumors

Clinical next-generation sequencing (NGS) assay choice requires careful consideration of panel size, inclusion of appropriate markers, ability to detect multiple genomic aberration types, compatibility with low quality and quantity of nucleic acids, and work flow feasibility. Herein, in a high-volume clinical molecular diagnostic laboratory, we have validated a targeted high-multiplex PCR-based NGS panel (OncoMine Comprehensive Assay) coupled with high-throughput sequencing using Ion Proton sequencer for routine screening of solid tumors. The panel screens 143 genes using low amounts of formalin-fixed, paraffin-embedded DNA (20 ng) and RNA (10 ng). A large cohort of 121 tumor samples representing 13 tumor types and 6 cancer cell lines was used to assess the capability of the panel to detect 148 single-nucleotide variants, 49 insertions or deletions, 40 copy number aberrations, and a subset of gene fusions. High levels of analytic sensitivity and reproducibility and robust detection sensitivity were observed. Furthermore, we demonstrated the critical utility of sequencing paired normal tissues to improve the accuracy of detecting somatic mutations in a background of germline variants. We also validated use of the Ion Chef automated bead templating and chip loading system, which represents a major work flow improvement. In summary, we present data establishing the OncoMine Comprehensive Assay-Ion Proton platform to be well suited for implementation as a routine clinical NGS test for solid tumors.

Adaptive control in high-speed electric drives of a lathe feed for noncircular turning

Problems of upgrading high-speed electric drives of a lathe feed for machining such bulk and precise products of engineering industry as internal combustion engine pistons with a complex ovate-barrel-like shape are considered. It is shown that these electric drives must have astaticism with respect to chip loading to decrease shape errors. When machining the piston surface, there are both uninterrupted cutting zones and cutting zones with an interruption on part of the spindle revolution as well (for example, when passing bores by a cutter etc.). It is shown that, at the same time, it is reasonable to have the structure with an integrally proportional controller and in the case of cutting interruption with a proportional controller. A controller is proposed with the structure changed as a function of the cutting feature. Application of the adaptive controller with the variable structure in the control system of lathe feed drives for noncircular turning decreases the shape error caused by uninterrupted cutting by 5–20 times in comparison with the linear integrally proportional controller. The additional effect of the application of the adaptive control is attained due to a significant (by several times) increase in the useful life of an expensive diamond cutting tool. The control of the controller structure is effective both in systems with the software formation of controlling actions and in systems using self-training principles.

Template preparation of AmpliSeq™ libraries using the Ion Chef™

The introduction of Next Generation Sequencing (NGS) techniques for forensic use has greatly expanded the possibilities of extracting information from biological stain materials in crime cases. However, the NGS workflows are not fully optimized for continuous, high-throughput processing of samples in forensic genetic laboratories. Although the Ion PGM™ has been on the market since 2010, the process of preparing samples for sequencing is still rather cumbersome and involves a large number of pipetting steps. This creates variability in the loading of the sequencing chips and in the sequencing coverage. This variability in turn complicates the interpretation of the results, i.e., low coverage leads to locus or allele dropout for poor performing markers. In order to automate a part of the sample preparation, we used the Ion Chef™ (Life Technologies) to prepare pooled Ion AmpliSeq™ libraries for emulsion PCR and loading onto sequencing chips. The workload and the number of manual pipetting steps were decreased while the chip loading efficiency, uniformity of loading and reproducibility was increased using the Ion Chef™ compared to the performance obtained with the more manual setup using the Ion OneTouch™ 2 system.

Optimizing the Dry Grinding Process on the Basis of Bond Materials

In order to decrease the negative environmental impacts of the cutting fluids (for example, disposal of grinding sludge) and also to reduce the manufacturing costs and the required space for the machines the dry grinding can be a conceivable alternative for the conventional grinding processes. Nevertheless, dry grinding has not been widely introduced into industry because of the high temperature generated in the grinding zone and difficulties of heat transfer without coolants. Selection of the proper grinding wheel bonds, grit sizes and concentration has significant effect on the grinding performance and the generated heat in the contact zone. This paper addresses the effects of the grinding wheel bond and the concentration on the dry grinding process efficiency through comparing the results of the carried out experiments with three resin bonded cBN-cup-wheels, each consisting different bond components. For this purpose, surface roughness and thermal damages during dry and wet grinding (utilizing grinding oil) by three different resin bonds were measured. The results show almost identical surface roughness values for dry and wet grinding. Furthermore, using the resin-kryolith-graphite bonded wheel leads to a reduction in thermal damages on the workpiece. Through different experiments, it was shown that the different bonds, used in this study, have significant influence on the chip loading of the grinding wheels. This is contributed to the different chip formation mechanisms and induced grinding temperatures when grinding by the different wheel bonds.

Targeted High-Throughput Sequencing For The Detection Of Mutations Associated With Myeloproliferative Neoplasms

BackgroundMyeloproliferative neoplasms (MPNs) are clonal hematopoietic stem cell disorders characterized by the proliferation of one or more myeloid cell lineages. Polycythemia vera (PV), essential thrombocythemia (ET) and primary myelofibrosis (PMF) are the classical types of Philadelphia negative MPN. The JAK2 V617F missense mutation is found in 95% of patients with PV and in 50-60% of patients with PMF or ET. Molecular screening for JAK2 V617F mutation in suspected MPN patients by pyrosequencing has become routine method in diagnostic services. With the introduction of new methods of screening, a growing number of mutations have been described in a range of genes that code for receptor structure proteins (MPL, JAK2 exon 12), intracellular signalling proteins (CBL, SH2B3, NF1, SOCS1/3), proteins involved in leukemic progression (TP53, NRAS/KRAS, NF1, IDH1/2), or epigenetic modifications (EZH2, ASXL1, TET2). Molecular genetic screening for these targets in JAK2 V617F negative cases can be laborious, time-consuming and expensive, but the advent of benchtop-class high-throughput sequencers and custom target enrichment platforms gives the opportunity to test all relevant mutations in multiple genes in a single assay. Aims: To evaluate the Ion Torrent PGM high-throughput sequencer and custom AmpliSeq capture platform for the screening of most relevant MPN associated mutations in JAK2 V617F negative cases and validate candidate mutations using pyrosequencing. Methods32 DNA samples (30 JAK2 V617F negative by pyrosequencing, 1 positive, 1 not tested) from patients with MPN disorders (thrombocytosis, neutrophilia or polycythemia) were screened (with appropriate ethical consent) for mutations using the Ion Torrent PGM sequencing platform. AmpliSeq multiplex primers were used for the target capture and the panel was designed via the online portal (v1.2), targeting 23 regions of 13 genes associated with MPN. The workflow involved library preparation and multiplex sample pooling following qPCR quantification (16 samples per run), emulsion PCR template preparation, Ion 318 chip loading and sequencing. Alignment and variant calling was via the Torrent Server 3.6.2 plugins, using custom coverage and hot-spot files to define the regions of interest. Variant calls were visualised using IGV and UCSC, and functionally annotated using CONDEL, Mutation Assessor and PROVEAN. Results31 of the 32 samples were successfully sequenced, with a mean depth of 1049 reads and the FASTQC plugin indicated good quality sequencing metrics. All JAK2 V617F negative samples were called V617F negative by the PGM. The V671F positive control sample was called at a frequency of 18.1% (19% by pyrosequencing). The untested sample was called positive (10%) for JAK2 V617F and this was validated using pyrosequencing (11%). No MPL or JAK2 exon 12 mutations were detected. Novel SNPs were seen in CBL (Chr11:119149062; G>A; intron 8-9), JAK2 (Chr9:5072649; T>C; intron 13-14), SOCS3 (Chr17:76354148; C>G; 3'UTR) and SH2B3 [(Chr12: 111856076; C>T; p.R43C) and (Chr12: 111856105; T>G; p.H52Q); both in exon 2]. Of these, the SH2B3 variants were flagged as deleterious (H52Q) and highly deleterious (R43C: SIFT=0; PPH2=0.998). Five samples (4 het, 1 hom) had a SNP in IDH1 associated with poor outcome in AML (rs11554137; MAF=0.05) and a further 6 samples had variants flagged as deleterious by at least one of the annotation platforms: one in SH2B3 [p.186I (rs183913232 )] and five in TET2 [2 samples with p.G355D (rs61744960); 2 with p.L34F (rs111948941) and one p.Y867H (COSM327337)]. Additionally, one sample with a TET2 L34F also had a COSMIC annotated JAK2splice site variant (c.1864+14C>T; COSM88203). SummaryThis study shows the ability of the Ion Torrent PGM and AmpliSeq platforms to analyse qualitatively and quantitatively multiple samples for multiple genes with good accuracy and specificity (no false positives for V617F), making this qualitative and quantitative method more time and cost-effective than traditional sequencing techniques. Additionally, several potentially disease-associated variants were detected, which would have been missed by conventional MPN screening strategies and we are proposing to roll this approach out as a diagnostic screening in our MPN clinic in the very near future. Disclosures:Milojkovic:BMS: Honoraria; Pfizer: Honoraria; Ariad: Honoraria; Novartis: Honoraria. Apperley:Novartis: Honoraria, Research Funding; Bristol Myers Squibb: Honoraria; Pfizer, Ariad: Honoraria (not direct from company), Honoraria (not direct from company) Other.

An investigation on surface grinding of hardened stainless steel S34700 and aluminum alloy AA6061 using minimum quantity of lubrication (MQL) technique

In grinding process, the abrasives plunge and slide against the workpiece during material removal with high specific energy consumption and high grinding zone temperature. To improve process efficiency, lubrication becomes an important requirement of the grinding fluids, along with chip removal and cooling the grinding zone. Grinding fluids have negative influences on the working environment and machining cost in terms of the health of the machine operator, pollution, the possibility of explosion (for oil), filtering, and waste disposal. The use of minimum quantity of lubrication (MQL) with an extremely low consumption of lubricant has been reported as a technologically and environmentally feasible alternative to flood cooling. This paper deals with an investigation of the grindability of hardened stainless steel (UNS S34700) and aluminum alloy AA6061 using dry, MQL, and conventional fluid techniques. One type of SiC and five types of Al2O3 wheels (corundum) as well as vegetable and synthetic ester MQL oils have been tested. The influences of wheel and coolant–lubricant types have been studied on the basis of the grinding forces, surface topography, and surface temperature. Synthetic ester MQL oil was found to give better grinding performance than the vegetable MQL oils. It was argued that the improved performance of the ester oil is caused by the formation of tribo-films on the abrasives and the workpiece, which enhances lubrication by inhibiting metal–abrasive interaction. Also, the grindability of the machined specimens was found to increase substantially by using the MQL grinding process with soft and coarse wheels. In MQL grinding of AA6061 alloy, the use of vegetable oil resulted in the lowest surface roughness, whereas using synthetic ester additives lead to highest surface roughness because of higher chip loading on the grinding wheel and consequently more redeposited material on the workpiece surface.

Specific energy distributions for sinusoidal multi-cutters in groove-sawing process

This paper proposes a new method for establishing the relations of specific energy of a material for sinusoidal multi-cutters in groove-sawing process. Effects of specific energy on sinusoidal multi-cutters with different cutter geometries, cutter locations, cutters arrangements, and cutter-by-cutter overlap ratios are studied. Experimental results prove that the specific energy is function of undeformed cutting areas in groove-sawing process. The groove sawing force in 3-axis is decomposed by cutting force in x-direction, side force in y-direction and vertical force in z-direction. The average specific energy of sinusoidal multi-cutters for workpiece Al 6061 in different wavelength (n=1–7) is 1580MPa, the average specific coefficient in y-direction is 0.44 and the average specific coefficient in z-direction is 0.20. The chip loading on each cutter is related to the average cutting depth, cutting width and cutter angle. The maximum chip loading of cutter order occurs in cutting overlap-area ratio between 0.22 and 0.23. The specific energy with multi undeformed cutting areas demonstrated the trend as the exponent decay. The specific energy varied with cutter location on sinusoidal wave, and the maximum variation of error occurred on cutter number n=3 per unit wave. The groove-sawing force model for sinusoidal-wave cutters can be established for the function of multi undeformed cutting areas by known specific energy, and it agreed well with the experimental results. Variations of error for sinusoidal multi-cutters are investigated for different cutter topologies. Through the geometry parameters design for multi-cutters to reduce specific energy on machining, the maximum material removal rate and longer tool life can be achieved.

Chip fractal geometry and loading characteristics of sinusoidal multi-cutters in hack-sawing process

This work proposed a sinusoidal-type discrete analytic geometry model and derives sinusoidal serrated chip loading characteristics equation for the simulation of the hack-saw reciprocating mechanism by the cutter analytic geometry. The chip loading with different wavelength units in hack-sawing process are studied. The factors affecting chip loading of unit wave, namely the length of the wavelength, the cutters numbers of unit wavelength, saw blade thickness, the equivalent cutting depth per tooth, the cutting overlap-area ratio per cutter edge, the pitch per each cutter, the cutting overlap-area factor, and the proportional factor of sinusoidal amplitude are investigated. The effects of sinusoidal cutter arrangement on chip loading are simulated by the chip loading equations. It is found that the maximum chip loading is always in the front of the cutters, which is at either the peak or the trough of different phase, while the numbers of wavelength unit is 3, 5, 7 and 40, respectively. The chip loading characteristics depend on the convolution of chip loading function, the cutter order window function and the cutter interval function. The simulated results from the established cutting force model for sinusoidal multi-cutters agree well with the experimental measurements. The wear location and failure types of cutters could be predicted for in hack-sawing process.

Comparative Assessment of Different Histidine-Tags for Immobilization of Protein onto Surface Plasmon Resonance Sensorchips

Surface plasmon resonance (SPR) is widely used to assess the kinetics and thermodynamics of binding of two molecules. The major challenge is immobilization of one molecule onto the sensorchip for robust detection of binding of the other molecule. We have compared a number of immobilization strategies for noncovalent attachment of an example protein (the substrate binding protein SiaP) by hexa-histidine (His), deca-His, and double-His tags to a nickel-nitrilotriacetic acid (NTA) surface. The stability of immobilization was assessed, and the binding of two low molecular weight ligands, Neu5Ac and 2-keto-3-deoxy-D-glycero-D-galacto-nononic acid (KDN), at different temperatures studied. The hexa-His tagged SiaP washed off from the surface too rapidly for ligand binding to be measured reliably. Systematic variation of chip loading identified conditions under which the deca-His tagged SiaP could generate reliable results. The double-His tagged protein performed as well as covalently attached deca-His tagged protein at 15, 25, and 35 °C. The observed ligand binding kinetics were comparable for all immobilization strategies, and thermodynamic values calculated from SPR are in agreement with solution-based isothermal titration calorimetry measurements. Extended trials suggest that covalent attachment is preferable for screening campaigns, whereas the double-His-tag strategy allows rapid regeneration of the chip, for example, when tight binding compounds are assessed.

Surface integrity in high speed end milling of titanium alloy Ti–6Al–4V

Machined titanium components, such as medical prosthesis, require the greatest reliability, which is determined by process induced surface integrity. However, surface integrity of milled titanium components easily deteriorates due to the poor machinability of titanium alloys and cyclic chip loading during milling. Milling induced surface integrity, including anisotropic surface roughness, residual stress, surface microstructure alterations and microhardness, has received little attention. In the present study, a series of end milling experiments were conducted to comprehensively characterise surface integrity at various milling conditions of titanium alloy Ti–6Al–4V with TiAlN coated carbide cutting tools. The experiments were carried out under dry cutting conditions. For a range of cutting speeds, feeds and depths of cut, analyses of machined surface roughness, residual stress, microhardness and the microstructural observations were carried out. The present work aims to evaluate the influence of different milling conditions on workpiece surface integrity.