High Feed Rate Research Articles

Multi-Response Optimization during the High-Speed Drilling of Composite Laminate Using the Grey Entropy Fuzzy Method (GEF)

The machining of glass-fiber-reinforced composites is complex due to their heterogeneous structures. Research has indicated that high-speed machining, at high spindle speeds and feed rates, not only increases productivity but also reduces drilling defects, such as delamination. However, there are several challenges with high-speed machining, such as the heat generated during drilling between the drill tool and chip contact surfaces that can result in hole size errors. Therefore, it is essential to determine the optimum drilling parameters. This paper presents an innovative hybrid optimization approach called Grey Entropy Fuzzy. This approach is a combination of entropy-based weight integrated Grey Relation analysis and fuzzy logic. With the consideration of all responses simultaneously, an optimum machining combination was obtained at a spindle speed of 12,000 rpm and a feed rate of 0.02 mm/rev using a drill bit with a point angle of 118° and a drill diameter of 6 mm.

A comparative study of consumption of Aedes aegypti and Aedes albopictus larvae by ornamental fishes to control their population in West Bengal

Aedes aegypti and Aedes albopictus are the carriers of a variety of diseases such as dengue, dengue hemorrhagic fever (DHF), chikungunya, zika virus, and yellow fever. An affordable way of vector management that effectively suppresses the mosquito population for a long time is the release of larvivorous fish. In this work, ornamental fish species are identified, and their potential larvicidal efficacy for biological control of Aedes mosquito larvae is assessed. The consumption rates of four ornamental fish species (Gold fish, Betta fish, Molly fish, and Guppy) for Aedes aegypti and Aedes albopictus larvae have been observed in the present study, and a comparison between the mean consumption rates of the four fish species for Ae. aegypti and Ae. albopictus has been recorded.The observation indicated practically no variance, and the intake rates for both types of larvae were almost same for the four species of fish. In contrast to guppy fish, the findings indicated that Goldfish, Black molly, and Betta fish had very high feeding rates. Therefore, in the near future, these fish can be thought of as efficient biological control agents for both Aedes aegypti and Aedes albopictus larvae.

A Feasibility Study on Directed Energy Deposition of SS 316L with Coaxial Wire-powder Feeding

Compared to single wire/powder feeding, the directed energy deposition (DED) technique with coincident wire-powder feeding enables the fabrication of metallic parts with high deposition efficiency and performance. The existing investigations on DED process with wire-powder feeding utilized the combination of lateral wire feeding and coaxial/lateral powder feeding. In addition, they found that the deposition efficiency and final performance can be improved by increasing the wire injection angle in a vertical plane. However, the DED of metallic parts with coaxial wire-powder feeding remains unexplored due to the machine limitation. In this paper, we studied the effects of powder feed rates on the surface quality, defects, and microstructure of as-built SS 316L parts with coaxial wire-powder feeding. The results found that the surface finish of wire-deposited samples is much better than as-built samples fabricated with high powder feeding rates. In addition, the dual feedstock DED process has a higher susceptibility to porosity than pure wire deposition due to the entrapped gas in powder particles, and the porosity increases with the powder feed rate. Moreover, the wire-deposited samples present more distinct melt pool boundaries than those fabricated with wire-powder feeding. With an increase in powder feed rate, the grain size and grain boundary thickness in the fusion areas experience a decrease first and subsequent increase. This paper will provide guidelines for the efficient production of high-performance metallic alloy/composites with coaxial wire-powder feeding.

PENGARUH PARAMETER PENGGURDIAN TERHADAP AKURASI LUBANG KOMPOSIT GONI-POLIESTER DENGAN TWIST DRILL

Composite is a combination of materials consisting of 2 or more materials lead to the composite material has different mechanical properties and characteristics as desired. Composite materials are divided into two types, synthetic fibers and natural fibers. Most of the natural fiber types use jute fiber, as it is a candidate as a reinforce material to produce lightweight, strong and environmentally friendly composite materials as mixing polyester composites. Although composites can be made according to the desired shape, the final work, such as the machining process, is also needed for making several shapes such as making holes with the drill process. Furthermore, twist drilling, can induce damage due to the imperfections of the holes that are produced, resulting asymmetrical holes. This allows complicate assembly and reduce its strength. The parameters use are spindle speed 100 rpm, 700 rpm and 1400 rpm and feeding 0,1 mm/rev, 0,2 mm/rev, 0,3 mm/rev, 0,5 mm/rev and 0,7 mm/rev. The results obtained that using 100 rpm and feeding 0.5 to 0.7 can make imprecise and resulted delamination of the hole. Increased spindle speed such as 700 and 1400 rpm and higher feed rate, resulted increase the accuracy of the hole

Experimental study of bone drilling by Kirschner wire.

Mechanical and thermal damage to the bone tissue during drilling process is inevitable and directly affects the postoperative recovery. According to clinical practices and present academic investigations, this study tries to reduce bone damage by experimental investigation of bone drilling by Kirschner wire considering the drilling force and temperature factors. Finite element method has been applied to modelling of the drilling process. Then, grouped experiments have been carried out using bovine femoral bone and analyzed based on the orthogonal experimental method. The influence of key parameters such as Kirschner wire bevel angle, feed speed and rotational speed on the microscopic bone chip size, drilling force, drilling temperature and hole inlet burr was analyzed to conduct comprehensive analysis and optimizations. It is certain that the chips size is closely related to drilling force and drilling temperature. The low drilling temperature does not mean that the damage area is small. The drilling process should be completed quickly at high feed rates. The lower rotational speed, Kirschner wire bevel angle, and higher feed rate help reduce the thermal damage area of the bone drill, effectively reduce the drilling force and hole entrance burrs.

Wear characteristics of multi-tooth milling cutter in milling CFRP and its impact on machining performance

Multi-tooth milling cutters with segmented right-hand helical cutting edge (SRHCE) and segmented left-hand helical cutting edge (SLHCE) could effectively reduce milling damages for carbon fiber reinforced polymer (CFRP) composites. However, rapid tool wear is still challenging for long-distance milling, and especially wear characteristics of multi-tooth milling cutter and their impacts have not been fully understood. This paper investigated the wear characteristics of the uncoated multi-tooth milling cutter with SLHCE and SRHCE under various feeds per tooth (0.01–0.15 mm/tooth) and a constant spindle speed of 3000 rpm and the effects of tool wear on machining performance by theoretical and experimental analyses. SLHCE and SRHCE experienced abrasive wear, while the wear of SLHCE is slighter than SRHCE because a clearance was formed between SLHCE and nominal tool periphery. Consequently, the profiles of worn SRHCE and SLHCE were different, and they were in ellipse arc and circular arc shape, respectively. The half axis length of ellipse arc worn profile of SRHCE decreased significantly with increasing feed per tooth, while the cutting edge radius of SLHCE changed irregularly. As tool wear aggravated with longer cutting distance, the machining qualities generally worsened, including increased burr damages and surface roughness, and cutting force also increased. Fewer burr damages were found on the top ply, as SLHCE dominated the cutting of the top ply with slighter tool wear because of the clearance, compared to the bottom ply, where SRHCE dominated cutting. In addition, the lowest feed per tooth (0.01 mm/tooth) induced severe tool wear and produced worse machining qualities, especially under longer cutting distances, while the milling force was relatively low. Therefore, more attention should be paid to the SRHCE for multi-tooth milling cutters, and a higher feed rate is preferred under similar conditions.

Impact of Melt Processing Conditions on the Degradation of Polylactic Acid.

To reduce the degradation of polylactic acid (PLA) during processing, which reduces the molecular weight of PLA and its properties, prior studies have recommended low processing temperatures. In contrast, this work investigated the impact of four factors affecting shear heating (extruder type, screw configuration, screw speed, and feed rate) on the degradation of PLA. The polylactic acid was processed using a quad screw extruder (QSE) and a comparable twin screw extruder (TSE), two screw configurations, higher screw speeds, and several feed rates. The processed PLA was characterized by its rheological, thermal, and material composition properties. In both screw configurations, the QSE (which has a greater free volume) produced 3–4 °C increases in melt temperature when the screw speed was increased from 400 rpm to 1000 rpm, whereas the temperature rise was 24–25 °C in the TSE. PLA processed at low screw speeds, however, exhibited greater reductions in molecular weight—i.e., 9% in the QSE and 7% in the TSE. Screw configurations with fewer kneading blocks, and higher feed rates in the QSE, reduced degradation of PLA. At lower processing temperatures, it was found that an increase in melt temperature and shear rate did not significantly contribute to the degradation of PLA. Reducing the residence time during processing minimized the degradation of PLA in a molten state.

Intra-seasonal variation in feeding rates and diel foraging behaviour in a seasonally fasting mammal, the humpback whale.

Antarctic humpback whales forage in summer, coincident with the seasonal abundance of their primary prey, the Antarctic krill. During the feeding season, humpback whales accumulate energy stores sufficient to fuel their fasting period lasting over six months. Previous animal movement modelling work (using area-restricted search as a proxy) suggests a hyperphagic period late in the feeding season, similar in timing to some terrestrial fasting mammals. However, no direct measures of seasonal foraging behaviour existed to corroborate this hypothesis. We attached high-resolution, motion-sensing biologging tags to 69 humpback whales along the Western Antarctic Peninsula throughout the feeding season from January to June to determine how foraging effort changes throughout the season. Our results did not support existing hypotheses: we found a significant reduction in foraging presence and feeding rates from the beginning to the end of the feeding season. During the early summer period, feeding occurred during all hours at high rates. As the season progressed, foraging occurred mostly at night and at lower rates. We provide novel information on seasonal changes in foraging of humpback whales and suggest that these animals, contrary to nearly all other animals that seasonally fast, exhibit high feeding rates soon after exiting the fasting period

Assessment of Hole Quality, Thermal Analysis, and Chip Formation during Dry Drilling Process of Gray Cast Iron ASTM A48

The cutting parameters in drilling operations are important for high-quality holes and productivity improvement in any manufacturing industry. This study investigates the effects of spindle speed and feed rate on temperature, surface roughness, hole size, circularity, and chip formation during dry drilling of gray cast iron ASTM A48. The results showed that the temperature increased as spindle speed and feed rate increased. The surface roughness had an inverse relationship with the spindle speed and direct relation with the feed rate. Furthermore, hole size increased with increased spindle speed and decreased as the feed rate increased, while hole circularity decreased with increasing both the spindle speed and feed rate. The analysis of variance (ANOVA) indicated that the spindle speed had the highest percentage contribution of 56.24% on temperature, followed by the feed rate with 42.35%. The surface roughness was highly influenced by the feed rate and the spindle speed with 55% and 44.12%, respectively. While the hole size was highly influenced by the feed rate with a 74.18% percentage contribution, and the contribution of spindle speed was 21.36%. In addition, the feed rate has a percentage contribution of 70.82% on circularity, which is higher than the spindle speed of 24.26% percentage contribution. The results also showed that thick and discontinuous chips were generated at higher feed rates, while long continuous chips were produced at high spindle speeds.

The Effect of the Different Types Plants on the Recirculating Aquaculture System (RAS) on the Growth Performnace of Carp Seed (Cyprinus carpio)

Intensification of culture through stocking densities and high feeding rates can cause water quality problems. Utilization of the recirculation system in intensive cultivation is important to maintain water quality. This study aims to determine the best type of aquatic plants in RAS for the growth of carp fish seeds. The research in January - February 2021. The test fish used were carp fish with a length of 6 - 7 cm and a weight of 3 - 5 gr. The feed used is commercial feed with a protein content of 31 - 33%. Feeding was carried out at 08.00 A.M and 04.00 P.M with 3% fish biomass. This study used an experimental method with CRD with 4 treatments and 3 replications. Treatment A (Control, without plants), treatment B (cotton fiber, bio balls, activated charcoal and kale), treatment C (cotton fiber, bio balls, activated charcoal and watercress plants) and treatment D (cotton fiber, bio balls, activated charcoal and pakchoy plants). The results showed that the use of different aquatic plants had a significant effect (P <0,05) on SR, SGR, length growth and absolute weight, plant height, and a number of leaves, but no significant effect (P> 0,05) on FCR. The best treatment in this study was B with an SR value of 82,22 ± 7,70%, SGR 4,08 ± 0,14%, absolute length 4,97 ± 0,27 cm, absolute weight 15,81 ± 1,96 gr, plant height 60,67 ± 18,01 cm, number of leaves 20,42 ± 9,66 leaves and FCR 1,10 ± 0,0896

Single and multi-objective optimization for cutting force and surface roughness in peripheral milling of Ti6Al4V using fixed and variable helix angle tools

Ti6Al4V titanium (Ti) alloy is a frequently used engineering material in industrial applications due to its superior properties. In this work, single-objective and multi-objective methods were used to optimize control factors (cutting speed, feed rate, and cutting tool helix angle) for minimal cutting force (Fc) and surface roughness (Ra) in peripheral milling of Ti6Al4V. Machinability experiments were performed using carbide end mill cutting tools with fixed and variable helix angles. Following the machinability tests performed using the L18 orthogonal array, the Taguchi technique was used as a single-objective optimization for each of the cutting forces and surface roughness. The Entropy-weighted TOPSIS approach was used in the second step to provide the optimum levels of the control factor, which minimizes both cutting force and surface roughness. The effects of control factors and interactions on thrust force and surface roughness were determined by Analysis of Variance (ANOVA) and contour plots. As a result of this study, it was determined that the helix angle of the cutting tool (84.91 % contribution) was the most effective parameter on the cutting force and the feed rate (22.71 % contribution) on the surface roughness. The cutting force and surface roughness values decreased in peripheral milling at high cutting speed, whereas the cutting forces increased, and the surface quality of the workpiece deteriorated in machining at high feed rates. The helix angle of the cutting tool has a favorable influence on the cutting force and surface roughness when milling with fixed helix tools. Cutting forces are minimized, and workpiece surface quality is improved using cutting tools with a larger helix angle. Variable helix tools with a large helix angle performed best in cutting force and surface roughness. Variable helix end mills with large helix angle (HA = 35°/38°), high cutting speed (Vc:108 m/min), and a low feed rate (f:0.04 mm/tooth) should be used in peripheral milling of Ti6Al4V Ti alloy to achieve both minimum cutting force and best surface quality. The mean cutting force and surface roughness values were obtained as 628.69 N and 0.363 μm, respectively, in the peripheral milling process performed at different levels of control factors. The cutting force was reduced to 227.52 N (34.71 % improvement) and the surface roughness value to 0.237 μm (276.32 % improvement) using the Entropy-weighted TOPSIS multi-objective optimization approach.

Effects of prey size on predatory behaviour of leech ( Whitmania pigra ) feeding on snails ( Cipangopaludina cathayensis )

Rapid development of medicine has led to increased use of leech (Whitmania pigra). The suitable feeding technology is the key factor for successful breeding leeches. However, there is little information available to concern the effect of prey size on predatory behaviour of the leeches. In this study, we conducted predation trials by two sizes of W. pigra preying on three sizes of snails (Cipangopaludina cathayensis), and then analysed predation rate, feeding rate, searching time and handling time. Our results demonstrated that there were higher predation rate of small-size W. pigra preying on small-size snails compared with medium or large ones, and the predation rates gradually decreased with prolongation of the predation time. In addition, the small-size W. pigra had higher feeding rates than larger size among three treatments. However, snail sizes did no have significant effects on the feeding rates of the leeches. Furthermore, we found that it took longer time of small-size leeches to search snails than large-size leeches, while the handling time of two sizes of W. pigra increased with the snail size. This study suggests that farmers should take smaller amount and more frequent feeding approach for leech larva in the artificial breeding processes. On the other hand, adult leeches should be provided with enough feeding in one time. Due to the size-specific feeding characteristics of the leeches, we suggest that leeches should be raised based on size.

Predicting ecological impacts of the invasive brush-clawed shore crab under environmental change

Globally, the number of invasive non-indigenous species is continually rising, representing a major driver of biodiversity declines and a growing socio-economic burden. Hemigrapsus takanoi, the Japanese brush-clawed shore crab, is a highly successful invader in European seas. However, the ecological consequences of this invasion have remained unexamined under environmental changes—such as climatic warming and desalination, which are projected in the Baltic Sea—impeding impact prediction and management. Recently, the comparative functional response (resource use across resource densities) has been pioneered as a reliable approach to quantify and predict the ecological impacts of invasive non-indigenous species under environmental contexts. This study investigated the functional response of H. takanoi factorially between different crab sexes and under environmental conditions predicted for the Baltic Sea in the contexts of climate warming (16 and 22 °C) and desalination (15 and 10), towards blue mussel Mytilus edulis prey provided at different densities. Hemigrapsus takanoi displayed a potentially population-destabilising Type II functional response (i.e. inversely-density dependent) towards mussel prey under all environmental conditions, characterised by high feeding rates at low prey densities that could extirpate prey populations—notwithstanding high in-field abundances of M. edulis. Males exhibited higher feeding rates than females under all environmental conditions. Higher temperatures reduced the feeding rate of male H. takanoi, but did not affect the feeding rate of females. Salinity did not have a clear effect on feeding rates for either sex. These results provide insights into interactions between biological invasions and climate change, with future warming potentially lessening the impacts of this rapidly spreading marine invader, depending on the underlying population demographics and abundances.

Two Strains of Gibel Carp (Carassius gibelio) Exhibit Diverse Responses to Carbohydrates in a Low-Lipid Diet

An 8-week feeding trial was conducted to investigate carbohydrate use in a low-lipid diet between different strains of gibel carp (Carassius gibelio). The wild-type Dongting strain and artificially selected CASIII strain were fed three levels of carbohydrate: 15%, 30%, and 45%, in a low-lipid formulation (4%). The results showed that low-lipid supplementation with high carbohydrate seems to improve the feeding rate (FR) and specific growth rate (SGR), while it did not result in hyperglycaemia in gibel carp. Transcriptional regulation was slightly affected by carbohydrate levels; only hepatic pfk expression was more increased in the 30% and 45% carbohydrate diets than in the 15% carbohydrate diet ( p < 0.05 ). Regarding the strains, CASIII obtained higher growth performance by having higher FR and SGR than Dongting ( p < 0.05 ). Relatively higher glycaemia was found in CASIII, and it was coupled with increased plasma triglycerides and insulin ( p > 0.05 ). Enhanced gene expression of pk involved in glycolysis and decreased mRNA levels of pepck in gluconeogenesis were also observed in CASIII ( p < 0.05 ). There were strong strain ∗ diet interactions of gene expression involved in lipogenesis, and Dongting had higher mRNA levels of srebp-1, acly, and fas when fed carbohydrate at 45% ( p < 0.05 ). In conclusion, the tolerant level of carbohydrates in a low-lipid diet could be up to 45% for gibel carp by an improvement of growth and noninducement of postprandial plasma glucose. CASIII had a better ability to use dietary carbohydrates for growth with active glycolysis and restrained gluconeogenesis, and Dongting had more potential in lipid metabolism in response to carbohydrate intake.

The influence of machining induced surface integrity and residual stress on the fatigue performance of Ti-6Al-4V following polycrystalline diamond and coated cemented carbide milling

Accurate fatigue life predictions of titanium alloy components requires an understanding of how the machining affected metallurgical and micro-mechanical subsurface condition influences fatigue crack nucleation and growth. This study investigates the influence of surface integrity features generated during carbide and high-speed polycrystalline diamond machining on the fatigue behaviour of coarse and fine-grained Ti-6Al-4V. Mechanically induced compressive residual stresses, promoted by higher feed rates and the larger cutting edge radii of carbide tools, have been demonstrated to provide an overriding enhancing effect on fatigue life due to crack initiation suppression and reducing the deleterious effects of microstructural deformation and surface imperfections.

A New Methodological Approach on the Characterization of Optimal Charging Rates at the Hydrogen Plasma Smelting Reduction Process Part 2: Results.

To meet the target for anthropogenic greenhouse gas (GHG) reduction, the European steel industry is obliged to reduce its emissions. A possible pathway to reach this requirement is through developments of new technologies for a GHG-free steel production. One of these processes is the hydrogen plasma smelting reduction (HPSR) developed since 1992 at the Chair of Ferrous Metallurgy at the Montanuniversitaet Leoben in Austria. Based on the already available publication of the methodology in this work, potential process parameters were investigated that influence the reduction kinetics during continuous charging to improve the process further. Preliminary tests with different charging rates and plasma gas compositions were carried out to investigate the impacts on the individual steps of the reduction process. In the main experiments, the obtained parameters were used to determine the effect of the pre-reduction degree on the kinetics and the hydrogen conversion. Finally, the preliminary and main trials were statistically evaluated using the program MODDE® 13 Pro to identify the significant influences on reduction time, oxygen removal rate, and hydrogen conversion. High hydrogen utilization degrees could be achieved with high iron ore feeding rates and low hydrogen concentrations in the plasma gas composition. The subsequent low reduction degree and thus a high proportion of oxide melt leads to a high oxygen removal rate in the post-reduction phase and, consequently, short process times. Calculations of the reduction constant showed an average value of 1.13 × 10−5 kg oxygen/m2 s Pa, which is seven times higher than the value given in literature.

Reduced concentration polarization and enhanced steam throughput conversion with a solid oxide electrolysis cell supported on an electrode with optimized pore structure

Conversion of steam to hydrogen in solid oxide electrolysis cells (SOECs) is largely limited by concentration polarization occurring in the supporting cathodes. The present study was thus aimed at reducing the concentration polarization and increasing the steam conversion by optimizing the pore structure of the cathodes. Button cells supported on cathodes with straight pore structure showed much improved performance than those with tortuous pore structure especially under steam-lean conditions (1.19 vs. 0.69 A•cm−2 at 1.3 V, 750 °C and 10% vol. % H2O). Impedance spectroscopy analysis indicated that the straight pore structure in the cathodes allowed for facile transport of steam, thus effectively mitigating the concentration polarization. The relation between the electrolysis current density and steam concentration determined from the button cells was used to simulate the electrolysis performance of single cells. The simulation predicts that single cells with the straight pore structure in the cathodes can achieve high steam throughput conversion even at high steam feeding rate.

Numerical and experimental investigation for the cladding of AISI 304 stainless steel on mild steel substrate using Gas Metal Arc Welding

In the present study, Gas Metal Arc Welding (GMAW) is used to deposit AISI 304 stainless steel layer on the mild steel substrate. The cladding parameters like welding voltage and feed rate have been varied to identify the deposited AISI 304 stainless steel bead profile and factors affecting the bead deposition on the mild steel substrate. Microscopic and EDS analysis confirms the successful deposition of the stainless steel layer on the mild steel substrate. The GMAW parameters like welding voltage and wire feed rate (WFR) govern the AISI 304 clad bead quality like clad profile, heat affected zone (HAZ), and clad penetration. A numerical model has also been developed using a double ellipsoidal heat source to identify the effect of welding parameters on the clad bead. The developed numerical model identifies the temperature distribution along with the clad bead profile and the model is identical with the experimental results. The experimental results showed that a non-uniform weld bead formation has been observed at lower voltage (14 V) and low WFR (3 m/min). The clad bead quality has improved with an increase in the welding voltage (16 V & 18 V) and wire feed rate (5 m/min & 7 m/min). However, cladding at a high wire feed rate (7 m/min) results in low dilution of the clad material with the substrate.

Electrospun Polymer Nanofibers with Antimicrobial Activity.

Nowadays, nanofibers with antimicrobial activity are of great importance due to the widespread antibiotic resistance of many pathogens. Electrospinning is a versatile method of producing ultrathin fibers with desired properties, and this technique can be optimized by controlling parameters such as solution/melt viscosity, feeding rate, and electric field. High viscosity and slow feeding rate cause blockage of the spinneret, while low viscosity and high feeding rate result in fiber discontinuities or droplet formation. The electric field must be properly set because high field strength shortens the solidification time of the fluid streams, while low field strength is unable to form the Taylor cone. Environmental conditions, temperature, and humidity also affect electrospinning. In recent years, significant advances have been made in the development of electrospinning methods and the engineering of electrospun nanofibers for various applications. This review discusses the current research on the use of electrospinning to fabricate composite polymer fibers with antimicrobial properties by incorporating well-defined antimicrobial nanoparticles (silver, titanium dioxide, zinc dioxide, copper oxide, etc.), encapsulating classical therapeutic agents (antibiotics), plant-based bioactive agents (crude extracts, essential oils), and pure compounds (antimicrobial peptides, photosensitizers) in polymer nanofibers with controlled release and anti-degradation protection. The analyzed works prove that the electrospinning process is an effective strategy for the formation of antimicrobial fibers for the biomedicine, pharmacy, and food industry.

Towards understanding the hole making performance and chip formation mechanism of thermoplastic carbon fibre/polyetherketoneketone composite

Here, we report the first study on the hole making performance of thermoplastic carbon fibre/polyetherketoneketone (CF/PEKK) composite. Different hole making methods (conventional drilling vs. helical milling) have been compared and the effect of different feed rates has been investigated. The effect of thermal-mechanical interaction on the resulting hole damage has been elucidated for the first time for carbon fibre reinforced thermoplastics (CFRTPs) hole making. In the material science dimension, advanced material characterization techniques have been deployed to reveal the material removal mechanisms at microscopic scale and unveil the underlying material structural change at a molecular level. Results show that the delamination damage of CF/PEKK is a result of the thermal-mechanical interaction. For conventional drilling, the high machining temperature (at low feed rate <0.1 mm/rev) has a stronger influence on the delamination damage and the delamination starts to show stronger dependence on the thrust force at high feed rate >0.1 mm/rev. In contrast, helical milling generates a much higher machining temperature which plays a more predominant role in the associated delamination damage. Microstructural analysis shows that all the hole surfaces feature matrix smearing, as a result of combined in-plane shear stress and high machining temperature. Conventional drilling leads to more severe hole wall microstructural damage (matrix loss and surface cavity) as compared to helical milling. Finally, thermal analysis reveals that the hole making process has led to significantly increased crystallinity in the PEKK matrix as a result of the strain-induced crystallization under the combined effect of shear stress and high temperature. • Hole making performance of CF/PEKK is investigated for the first time. • A comparative study on conventional drilling and helical milling is reported. • The role of thermo-mechanical interaction is elucidated for CF/PEKK hole making. • Chip morphology and the associated material removal mechanism are revealed. • Shear-induced crystallization caused by hole making is reported for the first time.