Cutting Edge Quality Research Articles

Influence of End Mill Manufacturing on Cutting Edge Quality and Wear Behavior

One of the decisive factors for the performance of milling tools is the quality of the cutting edge. The latter results from the process control of the individual steps along the tool manufacturing process chain, which generally includes the sintering or pressing of the blanks, grinding, cutting edge preparation, and coating of the tools. However, the targeted and application-specific design of the process steps in terms of high economic efficiency is currently limited by a lack of knowledge regarding the influence of the corresponding process parameters on the resulting cutting edge quality. In addition, there is a lack of suitable parameters that adequately represent the characteristics of the cutting edge microtopography. This publication therefore investigates the influence of manufacturing processes on cutting edge quality and wear behavior of end mills. On this basis, different characterization parameters for the cutting edge quality are derived and evaluated with regard to their ability to predict the wear behavior.

Fatigue strength assessment of cut edges considering material strength and cutting quality

In the present study, statistical analysis for previously reported cut edge fatigue test results is performed. Experimental fatigue tests are conducted for machined, plasma, and fiber laser-cut S960 edges to verify the effect of yield strength and cut edge quality, and to study the effect of the cutting method on fatigue performance. Experimental fatigue tests were complemented with hardness and residual stress measurements and metallurgical analyses with electron backscatter diffraction (EBSD) to characterize cut edge fatigue properties and to verify statistical analysis findings. The results show that cut edges can be divided into high- and low-quality categories. On the basis of these high- and low-quality categories, material strength, and applied cutting methods, FAT classes and recommended fatigue design practices are proposed.

Fabrication of high hardness microarray diamond tools by femtosecond laser ablation

The properties of machining tools limit the application of micro-texture for wear reduction and self-lubrication of workpiece in precision engineering. The CVD microarray diamond tools can satisfy abrasion resistance and high lifetime of the tool as well as fast and reliable manufacture of texture structures. In this paper, femtosecond laser is used to manufacture diamond tools with different microarray cutting edges for the flexibility of tool design and the manufacture of micro-tools without obvious edge brittle in contour. The process parameters that affect the cutting edge quality are evaluated. Laser ablation strategy plays an essential role in fabricating high quality of cutting edge and high material removal efficiency. The ‘outline paths and concentric arc paths filling’ ablation strategy can guarantee both the processing quality and material removal efficiency. The ablation speed and fluence directly affect the formation of microstructure and the requirements of different tool design characteristics can be met by changing the ablation speed and fluence. By controlling the parameters of laser ablation CVD diamond, the micro-tools with dual array for micro-cutting ductile and brittle workpiece are presented. In the subsequent micro-cutting experiments, the performance of diamond tools with dual scale microarray is analyzed. Compared with the existing single cutting edge micro-tools, microarray diamond tools have higher flexibility and efficiency in microtexture processing.

On-Site Learning Factories for Implementing Artificial Intelligence Systems in Production

When introducing a disruptive technology such as artificial intelligence (AI) into a company, it is important to involve the employees from the beginning and to inform them comprehensively about the opportunities and risks of the technology. Traditional means of communication such as information brochures, company meetings and email circulars are not suitable for this purpose, as they only allow limited feedback and often present the workforce with a fait accompli. The KI_Cafe method presents a new kind of introduction strategy that follows an on-site learning factory concept. This includes information and discussion opportunities for all participants based on example scenarios, as well as the development and testing of a specific AI system. For this purpose, a requirements definition, system development and practical implementation of an AI-based assistance system are combined with recurring company-public experimental spaces, the KI_Cafe Learning factory. In a use case, a novel-based system for assessing the cutting edge quality of milling tools is developed and implemented for two small and medium sized enterprises. This enables an independent assess the condition of a milling tool and thus contributes to relieving the workload of the integrated tool pre-setting. During the development, all organizational levels from the machine operators to the managers will be included in order to map the individual needs of the device and to create an understanding of the AI system at an early stage. Accompanying this, various exhibits on the topic of AI and the current development status of the new measuring system will accessible in the KI_Cafe.

Ultrashort-pulsed laser separation of glass-silicone-glass substrates: influence of material properties and laser parameters on dicing process and cutting edge geometry

In recent years, ultrashort-pulsed lasers have increased their applicability for industrial requirements, as reliable femtosecond and picosecond laser sources with high output power are available on the market. Compared to conventional laser sources, high quality processing of a large number of material classes with different mechanical and optical properties is possible. In the field of laser cutting, these properties enable the cutting of multilayer substrates with changing material properties. In this work, the femtosecond laser cutting of phosphor sheets is demonstrated. The substrate contains a 230 µm thick silicone layer filled with phosphor, which is embedded between two glass plates. Due to the softness and thermal sensitivity of the silicone layer in combination with the hard and brittle dielectric material, the separation of such a material combination is challenging for both mechanical separation processes and cutting with conventional laser sources. In our work, we show that the femtosecond laser is suitable to cut the substrate with a high cutting edge quality. In addition to the experimental results of the laser dicing process, we present a universal model that allows predicting the final cutting edge geometry of a multilayer substrate.

Process strategies for laser cutting of electrodes in lithium-ion battery production

The growing competition in electric mobility is leading to an increased demand for inexpensive, high-performance lithium-ion batteries. In order to meet both objectives, optimization of the entire production chain is indispensable. In this work, the laser cutting of electrodes as one of the core processes in large-format battery production is addressed. A comprehensive literature review on the boundary conditions and the relevant quality characteristics of the separation process is presented. Furthermore, experimental findings regarding the dependency between cutting edge quality and achievable process speed of pulsed and continuous wave fiber lasers in the near infrared spectrum are compared. Finally, the design of customized cutting strategies based on multiple laser scan cycles is shown and the potential for the implementation in the battery production is discussed.

Coaxial camera-based monitoring of fiber laser cutting of thick plates

Laser cutting is a conventional and well-established industrial process within the sheet metal working domain. However, processing of thick plates remains a major problem due to the limited process window. Real-time monitoring for adaptive control might significantly decrease the risk of a cut fail. Up to this point, most studies were mainly focused on the design of monitoring systems for laser cutting with CO2 lasers and limited to either fusion or flame cutting. Nowadays, laser cutting by means of fiber lasers has become the industrial method of choice, however, no tailored generic monitoring solutions for this process have yet been reported in the literature. This paper investigates a coaxial camera-based monitoring system for 4 kW ytterbium fiber laser cutting of 15 mm mild steel and 12 mm stainless steel plates. Experiments at various cutting speeds, resulting in different cut edge quality outcomes, have been conducted. Intensity, geometrical and variability features of the obtained images have been calculated and analyzed. The correlation between the cut specimen quality and process images obtained by means of a high-speed visual camera is discussed for both fusion and flame cutting.

Design of Polypropylene Random Co-Polymer Pipe Cutter

The purpose of this research is to design disc cutter for cutting poly propylene random co-polymer (PPR) and high density polypropylene (HDP) extrudates. Analytical methods and software including like Catia and ANSYS are used to design the tool and analyze the effect of load on the cutter. In designing the disc Cutter, using the digital logic method of material selection, the optimum material, carbon steel 19573 with the least cost, locally obtainable, manufacturable and with hardness 63.42HRC is selected. The desired optimum combination of hardness and toughness of the cutter is obtained using hardening temperature 10200C, tempering temperature 2000C, and tempering time 120min which finally gives a hardness value of 63.42HRC. The strength and quality of cut edge are tested by cutting hard plastic PPR pipe with maximum thickness of 12.9mm. By the same setup of the cutter used in the factory the prototype disc cutter serves and its failure rate improves from cutting 150 to 250 PPR pipe pieces which was recognized by the industry. The research results can be used to design the cutter disk and fabricate a cutter with enough strength to cut different thickness of PPR pipes without breakage, reducing unwanted additional cost.

Laser cutting of ductile cast iron

Abstract The laser cutting method of the conventionally used material nodular cast iron, including the technological parameters influencing its cutting edge quality, is described in this paper. Samples were created by using different laser cutting technological parameters. The parameters, varied during the experiments, included the type of assist gases (O2 and N2/O2 combination - with different ratios of the two gases) and the cutting speed (within a range of 1.6 mm/min to 0.32 mm/min). Both parameters were changed until the desired properties of the cut surface were obtained. The heat affected zone’s width, microstructure and roughness parameters, were monitored for samples of thickness t = 13 mm. Results of the heat affected zone width measurements and its microstructure are shown in figures and evaluated for comparison purposes. The laser cutting principles and technology are briefly described, as well (properties of the CO2 laser beam, laser cutting input parameters, assist gases, interaction with the target material and stability of the cutting process).

Efficiency of Laser-Shaped Photovoltaic Cells

The main aim of this paper is to analyze the influence of laser shaping of the photovoltaic cell based on its efficiency. The authors described both process of the monocrystalline photovoltaic cell manufacturing, its efficiency, and the possibilities of usage in architecture and the process of creating the photovoltaic cells of unconventional shapes by using laser technology. A method for cutting photovoltaic cells using a fiber laser was presented as well as the parameters of the laser cutting process. The described method allows cutting the massively produced silicon cells according to the predetermined trajectory. Using the proposed process parameters, satisfactory cutting edge quality, and negligible impact of the laser beam on changes in the structure of the photovoltaic cell active layers were achieved. In each cycle of structure cutting, only a small part of the material is removed (from 1 to 2 μm), and depending on the thickness, the process is repeated from 50 to 300 times. It has been shown that the efficiency of the modified cells depends on the ratio of their surface area to the laser cutting line.

Outreach and support in South-London (OASIS) 2001—2020: Twenty years of early detection, prognosis and preventive care for young people at risk of psychosis

This study aims to describe twenty years of early detection, prognosis and preventive care in the Outreach and Support In South-London (OASIS) mental health service for individuals at Clinical High risk of psychosis (CHR-P). The study presents a comprehensive analysis of the 2001– 2020 activity of the OASIS team encompassing core domains: (i) service characteristics, (ii) detection, (iii) prognosis, (iv) treatment and (v) clinical research. The analyses employed descriptive statistics, population-level data, the epidemiological incidence of psychosis, Kaplan Meier failure functions and Greenwood 95% CIs and Electronic Health Records. OASIS is part of the South London and Maudsley (SLaM) NHS trust, the largest European mental health provider, serving a total urban population of 1,358,646 individuals (population aged 16-35: 454,525). Incidence of psychosis in OASIS's catchment area ranges from 58.3 to 71.9 cases per 100,000 person-years, and it is higher than the national average of 41.5 cases per 100,000 person-year. OASIS is a standalone, NHS-funded, multidisciplinary (team leader, consultant and junior psychiatrists, clinical psychologists, mental health professionals), transitional (for those aged 14-35 years) community mental health service with a yearly caseload of 140 CHR-P individuals. OASIS regularly delivers a comprehensive service promotion outreach to several local community organisations. Referrals to OASIS (2366) are made by numerous agencies; about one-third of the referrals eventually met CHR-P criteria. Overall, 600 CHR-P individuals (55.33% males, mean age 22.63 years, white ethnicity 46.44%) have been under the care of the OASIS service: 80.43% met attenuated psychotic symptoms, 18.06% brief and limited intermittent psychotic symptoms and 1.51% genetic risk and deterioration CHR-P criteria. All CHR-P individuals were offered cognitive behavioural therapy and psychosocial support; medications were used depending on individual needs. The cumulative risk of psychosis at ten years was 0.365 (95%CI 0.302-0.437). At six years follow-up, across two-third of individuals non-transitioning to psychosis, 79.24% still displayed some mental health problem, and only 20.75% achieved a complete clinical remission. Research conducted at OASIS encompassed clinical, prognostic, neurobiological and interventional studies and leveraged local, national and international infrastructures; over the past ten years, OASIS-related research attracted about £ 50 million of grant income, with 5,922 citations in the international databases. Future developments may include broadening OASIS to prevent other serious mental disorders beyond psychosis and fostering translational risk prediction and interventional research. With a twenty-years activity, OASIS’ cutting-edge quality of preventive care, combined with translational research innovations, consolidated the service as a leading reference model for evidence-based prevention of psychosis worldwide.

Laser cutting of ductile cast iron

Abstract The laser cutting method of the conventionally used material nodular cast iron, including the technological parameters influencing its cutting edge quality, is described in this paper. Samples were created by using different laser cutting technological parameters. The parameters, varied during the experiments, included the type of assist gases (O2 and N2/O2 combination - with different ratios of the two gases) and the cutting speed (within a range of 1.6 mm/min to 0.32 mm/min). Both parameters were changed until the desired properties of the cut surface were obtained. The heat affected zone’s width, microstructure and roughness parameters, were monitored for samples of thickness t = 13 mm. Results of the heat affected zone width measurements and its microstructure are shown in figures and evaluated for comparison purposes. The laser cutting principles and technology are briefly described, as well (properties of the CO2 laser beam, laser cutting input parameters, assist gases, interaction with the target material and stability of the cutting process).

Experimental Investigation of Industrial Laser Cutting: The Effect of the Material Selection and the Process Parameters on the Kerf Quality

Laser beam cutting is a non-contact, production-flexible and highly productive technique that allows accurate profiling of a wide range of sheet materials. To these and further benefits, laser machining is increasingly being adopted by industry. This paper investigates the effect of material type, workpiece thickness, cutting speed and assistant gas pressure on cut quality for industrial-relevant applications using a CO2 laser. AlMg3 aluminum alloy, St37-2 low-carbon steel and AISI 304 stainless steel were selected to represent the most established materials in many industrial fields and gain insight into different processes (i.e., inert-assisted fusion cutting and oxygen cutting) and absorption behaviors with respect to CO2 laser wavelength. The aim was to enhance the understanding of the mechanisms through which laser cutting parameters and workpiece parameters interact in order to identify general criteria and well-optimized process parameters which guarantee the kerf quality. The quality of laser cut was analyzed in its basic terms: kerf geometry, surface roughness and cut edge quality. The experiments were performed by using a systematic experimental design approach based on Design of Experiments, and the results were validated via Analysis of Variance. Quality assessment was presented and discussed. The visual inspection of cut sections confirms good overall quality and limited presence of laser cut imperfections. The experimental investigation demonstrates that the different materials can be successfully processed within a wide range of the tested values. In addition, optimum cutting conditions which satisfy the straight requirement of the quality standard adopted are identified for each material. This study involves an analysis of both phenomenological and practical issues.

The Use of Lasers at Various Stages of the Manufacturing Process of Solar Cells Based on Crystalline Silicon

The purpose of this chapter of the book is to present knowledge on the use of laser technology in silicon photovoltaic cell manufacturing processes. Particular consideration was given to the technique of using a disk laser to cut the edges of silicon wafers together with the recognition of the flow of laser micromachining on the quality of cut edges to obtain their minimal deformation. The second topic described is the method of producing point contacts employing laser radiation between a layer of vaporised aluminium and crystalline silicon using the Nd:YAG laser. The results illustrating the impact of the structure and parameters of point contact for a given laser radiation energy on basic electrical parameters for complete, prototype solar cells are included. The chapter in the book provides an overview of the literature on the above topics and presents selected results of experimental works carried out by the authors. The motive for its publication is the need to present selected results of own research carried out in the Welding Department cooperating for many years with the Institute of Engineering and Biomedical Materials (IMIiB) of the Silesian University of Technology and the Institute of Metallurgy and Materials Engineering (IMIM) of the Polish Academy of Sciences in Cracow.

Study of Shear-Cutting Mechanisms on Wood Veneer

Multi-material structures made from renewable materials are increasingly being addressed in research and industry. Especially lightweight applications based on wood and polymer materials offer an important opportunity to reduce weight and CO2 emissions, and thus create a sustainable economy. When establishing new material combinations, it is necessary to take economical and efficient manufacturing processes into count to enable the market entry. Therefore, the existing manufacturing processes needed to be adapted and improved in terms of the specific machining characteristic of the wood material. This study targets a combined process where a forming and shear-cutting process is also integrated in an injection-molding tool. The findings on the shear-cutting process of wood veneers are not widely investigated yet. Therefore, process and material-related dependences like cutting velocity, tool shape design, and preconditioning of wood veneers were examined. The target values cutting force and cutting-edge quality were used to describe the relations. The results showed specific damage and fiber fractions of the wood material compared to the isotropic materials (e.g., metal). In addition, low cutting forces appeared by realizing a drawing cut and high cutting speeds. A decrease in the cutting force with a higher moisture content could not be shown for the used wood types.

Influence of shear-slitting parameters on workpiece formation, cut edge quality and selected magnetic properties for grain-oriented silicon steel

The traditional process of mechanical cutting of electrotechnical steels, still have many advantages such as: high efficiency, no thermal deformation zone affected by hot ablation, the possibility of shaping products of any length of the cutting line. However, this process introduces a substantial plastic deformation to the sheet metal and causes premature edge fracture during the subsequent forming process. This causes the deterioration of the magnetic properties of material. The paper studies the effects of the technological parameters of shear- slitting process on residual stresses and strains, quality of sheared edge and selected magnetic properties based on ET 122-30 grain oriented electrical steel. For the study, a simulation model ofthe process using mesh-free method (SPH) is developed. To obtain knowledge of the influence of this parameters on quality of cut surface and magnetic properties of material, experimental research was done using vision-based measurement system, confocal and atomic force microscopes and system for testing soft magnetic materials. Finally, an example of graphical optimization is presented and set of acceptable solutions is developed on the plane of controllable variables. Using obtained relationships and results, it is possible to control cutting process to obtain high cut surface quality with minimum deterioration of magnetic properties.

Transnational education delivery in Ghana: examining the benefits, challenges and future prospects

ABSTRACT Transnational education (TNE) has developed over the years as a branch of international education that focuses on cross-border teaching and learning through local partners and branch campuses in host countries. While there have been concerns over the quality of TNE delivery in host countries, there is a paucity of empirical research that highlights education delivery, especially in host institutions. This study examines the benefits, challenges and prospects of TNE delivery in a host institution in Ghana. Using a mixed-method approach, we collected and analysed data from management representatives (n = 2), academic staff (n = 5) and students (n = 197). Results show that TNE enhances students’ learning experiences through diversified and reflective curriculum, highly rated pedagogical approach and acquisition of knowledge in global business practices. Lecturers reported enhanced pedagogical skills and knowledge of cutting-edge quality assurance and assessment processes. Challenges such as lack of clear policy guidelines governing TNE partnership, cultural differences among partners, inadequate learning resources for students, high cost of fees and difficulty in designing a bespoke curriculum to meet local needs were highlighted. The study further articulates the importance of developing policies that guide TNE delivery and the relationship between partners by regulatory bodies in the higher education sector.

Experimental and numerical investigations of the mechanical behavior of half sandwich laminate in the context of blanking

In this study, the complex mechanical behavior of an aluminum/low-density polyethylene (LDPE) half sandwich structure was investigated during the blanking process. Mechanical tests were conducted for the polymer and metal layer and the delamination behavior of the adhesive between the two layers. A new testing device was designed for detecting the delamination under tensile mode. Corresponding finite element models were established for the mechanical tests of the metal layer and the delamination of both layers for inverse parameter identification. Material parameters for Lemaitre-type damage, Drucker-Prager, and cohesive zone models were identified for the metal, polymer, and adhesive, respectively. A finite-element (FE) model was established for the blanking process of the sandwich structures. The experimental force-displacement curves, obtained in the blanking process of the half sandwich sheet, were compared with the predicted results of the FE model. The results showed that the predicted force-displacement curves and the experimental results were in good agreement. Additionally, the correlation between cutting clearance and changes in the force-displacement curves was obtained. Three feature values quantitatively described the imperfection of the experimental cutting edge. The effect of punch clearance on these values was studied numerically and experimentally. The results indicated that a smaller clearance generated a better cutting-edge quality. The stress state of the half sandwich structure during blanking was analyzed using the established FE model.

Impact of the thermally induced focus shift on the quality of a laser cutting edge

The phenomenon of thermal focus shift in optical systems, mainly caused by thermal lensing, is well known. There are numerous publications dealing with this effect, but they do not answer the question of how relevant this problem is to the practical application of lasers in laser cutting machines. In this paper, we examine the effect of the thermally induced change of the focus position on the quality of the cut edge when laser cutting 3 mm thick stainless steel with an 8 kW disk laser. After measuring the magnitude of the focus shift, its impact on the quality of the resulting cutting edge was determined for three different scenarios: recommended process parameters, increased speed, and decreased gas pressure. Roughness and perpendicularity tolerance were used to quantify the quality of the cutting edges according to the ISO standard. It becomes clear that it is difficult to explain the effect of the change in the focus position on quality aspects in general, as this also depends on other process parameters. Nevertheless, it can be shown that the resulting cut edge quality decreases in all three scenarios as a result of the thermal focus shift. This problem cannot be avoided by simply changing the process parameter corresponding to the focal position in the opposed direction of the thermal behavior before starting. Even though the reduction of quality might not be severe today, the focus shift should be considered for all applications that require a very high cutting quality. Furthermore, this effect cannot be neglected anymore as laser power will continue to rise in the future.

Improvement of Laser Beam Fusion Cutting of Mild and Stainless Steel Due to Longitudinal, Linear Beam Oscillation

The latest research on laser beam fusion cutting (LBFC) with static beam shaping have shown a limitation in the quality of cut parts for thick steel plates (> 6 mm) when using solid state lasers. The approach of dynamic beam oscillation has recently shown to be capable of overcoming this challenge, allowing to increase the cutting speed as well as improving cut edge quality beyond the state of the art. The present paper investigates the influence of longitudinal, linear beam oscillation in LBFC of 12 mm mild and stainless steel plates by analyzing different parameters as cutting speed, burr, surface roughness, heat affected zone (HAZ), and recast layer. Reasons for the observed process improvements compared to static beam shaping have been discussed. The adjustment of the energy deposition and interaction time of the laser beam with the material found to be most relevant for optimizing the LBFC process. In particular, for beam oscillation, a gradual energy deposition takes place and increases the interaction time. This reduces the heat input in terms of HAZ and recast layer by more than 50%, resulting in high cut edge quality and more than 70% faster cutting speed.