CAM System Research Articles

Processing of quasi-equidistant surfaces with the detection of the dependence of the roughness parameters on the tool pitch in the cam system

This article discusses the basic principles of generating a tool path when processing quasi-equidistant surfaces. The review and analysis of the origin of the automation of technological preparation of production in the world is carried out. The concept of integrated automated production is revealed. Considered are the leading enterprises that were among the first to introduce computer-aided design systems. The article discusses technologies for processing complex surfaces with the maximum removal of the metal layer from the work piece, with the maximum approximation to the given shape. The types of complex spherical surfaces have been identified, the processing of which is a complex technological process that requires a high level of qualifications of a specialist and expensive equipment. Before the introduction of automated machine control, such types of complex surfaces were almost impossible to process, the geometry was only close to the real one. Here we consider a modern CAM-system, which is a complex software package. Over the past decade, several generations of CAM systems have changed. When forming the tool path, it is possible to use the functions of their viewing and editing. In most cases, the system automatically generates the tool path based on the cutting geometry and machining parameters. The authors proposed a method for creating a machining path in the NX CAM environment. In this work, the optimal trajectory of the tool movement is determined, the cutting pattern is selected for processing quasi-equidistant surfaces, the cutting modes, the cutting tool, and the overlap step between passes are determined.

English

BACKGROUND Nowadays, the use of computer aided design / computer aided manufacturing (CAD / CAM) in fabricating indirect restoration such as onlay, crown and bridge has increased tremendously. However, there is lack of clinical information and evidence on current material and fabrication techniques of CAD / CAM post and core. This paper describes the classification of the post and core system and review current perspectives on recent development of CAD / CAM post and core. An electronic search of the literature was performed via PubMed and Scopus database, using the keyword (post and core) and (CAD / CAM) and (CAD / CAM post and core) as MeSH term. Articles eligible for inclusion in the present review were published in English, journal article and dated from January 2000 until November 2020. A total of 31 publications consisting of 18 in-vitro studies, 7 case reports, 4 finite element analysis and 2 clinical techniques were included in this review. Analysis parameters included are options of chairside CAD / CAM materials, CAD / CAM system and milling machine used, advantages and disadvantages and future direction of CAD / CAM post and core. CAD /CAM post and core can be alternative option as compared to the custom-made post and core and prefabricated post and core. KEY WORDS Computer - Aided Design, Computer - Aided Manufacturing, Dental Material, Indirect Restoration, Post and Core

REEK as a material for making fixed partial dentures with CAD/CAM systems

Polyetheretherket (PEEK) is a synthetic, tooth-colored polymeric material that has been used as a biomaterial in orthopedics for many years. PEEK is a partially crystallized, thermoplastic material, resistant to high temperature, with a melting point of 400 ° C and is suitable for pressing various dental prostheses. The purpose of this report is to present the possibilities of PEEK as a material for making fixed partial dentures with CAD/CAM systems. Material and methods: Examples are presented for the production of various structures from PEEK with the help of CAD / CAM systems or according to the methodology Press2, on which a composite inlay is made. Results: The chip resistance of CAD / CAM fabricated PEEK fixed prostheses is much higher than that of lithium disilicate glass-ceramics, alumina and zirconium. Due to its mechanical and physical properties, which are similar to those of bone and dentin, PEEK can be used for a number of applications in dentistry. Conclusion: PEEK is an attractive material that can be used in the manufacture of fixed and removable dentures using CAD/CAM systems, due to its excellent mechanical properties compared to materials such as acrylic plastics. Further studies and clinical trials are needed to investigate the application of this material and possible modifications for further applications in dentistry.

Accurate prediction of machining feedrate and cycle times considering interpolator dynamics

This paper presents an accurate machining feedrate prediction technique by modelling the trajectory generation behaviour of modern CNC machine tools. Typically, CAM systems simulate machines’ motion based on the commanded feedrate and the path geometry. Such approach does not consider the feed planning and interpolation strategy of the machine’s numerical control (NC) system. In this study, trajectory generation behaviour of the NC system is modelled and accurate cycle time prediction for complex machining toolpaths is realised. NC system’s linear interpolation dynamics and commanded axis kinematic profiles are predicted by using finite impulse response (FIR)–based low-pass filters. The corner blending behaviour during non-stop interpolation of linear segments is modelled, and for the first time, the minimum cornering feedrate that satisfies both the tolerance and machining constraints has been calculated analytically for 3-axis toolpaths of any geometry. The proposed method is applied to 4 different case studies including complex machining toolpaths. Experimental validations show actual cycle times can be estimated with > 90% accuracy, greatly outperforming CAM-based predictions. It is expected that the proposed approach will help improve the accuracy of virtual machining models and support businesses’ decision-making when costing machining processes.

AN ASSESSMENT OF THE DISPLACEMENT OF A CAM FOLLOWER USING REGULA FALSI METHOD

Cam is a mechanical component that transforms circular motion to reciprocating motion by using mating component, called the follower. The principal aim of this work was to study and analyse the displacement of a cam-follower with Regula Falsi method and verify its input by using MATLAB and FORTRAN simulations. A study was conducted on angle of rotation and the displacement of the follower, which is equal to the radius of the cam given as transcendental equation to find the exact solution. The parameters such as initial guess, final guess, iteration counter and the desired displacement are involved in finding the angular displacement to the cam system in high speed rotation. The analysis was done using a computer programming that enables verification of the results obtained and ascertaining whether the inputs are correct or not for the displacement in cam follower system. The computer output showed results of the two data sets that yielded solutions and two that did not. The results revealed that the programme could be used to find the angular displacement corresponding to a given follower displacement for any cam; if the function CAMF is modified to include the appropriate radius function, r(x). The results further revealed that at a halve cycle of a rotating cam, which is equivalent to (x = 3.142 rad), is a solution that would provide the desired displacement of the follower (opening and closing of valves).

Study on Development of an Operation Planning System Based on Case-Based Reasoning Using Machining Features

High-speed and high-precision machine tools developed recently have contributed to shorten machining time in parts machining. However, it consumes long time to determine operation parameters such as machining area, machining method, cutting tool and cutting conditions, and they deeply depend on operators' knowledge and experience. Thus, the preparation time before parts machining remains as a critical issue to be solved to achieve high-mix low-volume production. Therefore, in order to improve the efficiency of process planning, this study proposes an operation planning system to derive operation parameters based on case-based reasoning using recognized machining features. By using information of machining features, it becomes possible to widely deal with operation parameters such as not only cutting tool and cutting conditions, but also tool approaching and retracting patterns that are required to be input in CAM system. Additionally, since machining cases are added to a case database sequentially, the rules for case retrieval are automatically adjusted to utilize the past machining cases effectively in this system. From the result of a case study, it is confirmed that the developed system has a possibility to derive proper operation parameters in parts machining.

Biofluorometric Real-Time Image Sensing of Transcutaneously Emitted Ethanol Vapor By Enzyme-Immobilized Mesh Sheet

Introduction Human derived volatile organic compounds (H-VOCs) had been attracted as relating to disease and metabolism since the era of ancient Greece. Because some H-VOCs, which reflect internal body conditions, are dissolved in the blood and unconsciously released in breath and/or transcutaneously, measurement of H-VOCs realize non-invasive disease screening and assessment of metabolism [1]. In this work, targeting transcutaneously emitted ethanol (TrEtOH) vapor as a typical H-VOC, we developed a biofluorometric real-time image sensing system with high sensitivity (skin-gas cam). Alcohol dehydrogenase (ADH), which enzymatically reduces nicotinamide adenine dinucleotide (NAD) using EtOH as another substrate, was utilized for real-time quantitative detection of TrEtOH. Furthermore, we examined the spatiotemporal and quantitative imaging of TrEtOH at various body sites when the subject took alcohol orally. Detectability and sensitivity in relation to each skin tissue were precisely analyzed. Materials and Methods ADH was immobilized on a cotton mesh, which was shaped to fit with a body shape for equalizing a distance between the body surface and the mesh. The ADH was covalently cross-linked by glutaraldehyde on a cotton mesh. The ADH-enzymatic reaction of oxidized NAD+ and EtOH was employed on the skin-gas cam (Fig.1a). The gas-imaging was achieved utilizing fluorescence of the reduced product—NADH (λex = 340 nm, λem = 490 nm). The optical system was constructed with a highly-sensitive CMOS camera, a UV-LED ring-light (λcenter = 340 ± 5 nm), and two bandpass filters (Fig. 1b).A dynamic range of the skin-gas cam was evaluated over 0.005–300 ppm EtOH vapor prepared by a standard gas generator at a constant flow rate of 100 mL/min for 20 sec. EtOH-specific selectivity was also tested with various kinds of VOCs contained in transcutaneous gas at 1 ppm each.The human subject experiment was approved by Tokyo Medical and Dental University (code: 2018-M160). Subjects took distilled liquor at the amount of 0.4 g of EtOH per 1 kg of body weight within 15 min. And then, TrEtOH was measured by the skin-gas cam for 45 min. Results and Discussions The spatiotemporal distribution of EtOH concentration was quantitatively detected by the fluorescent light intensity on the ADH-immobilized mesh. A time-domain image analysis computed a rate of ADH-mediated reaction based on the NADH fluorescence video [2]. The enzymatic reaction rate reached a maximal value at 30 sec after standard EtOH vapor application. A correlation between the maximal values of reaction rates and EtOH vapor concentrations was obtained over 0.02–300 ppm, which covered the concentration range of TrEtOH after alcohol intake in the human subject experiment. Moreover, the ADH-immobilized mesh sensor showed significant specificity to EtOH.The high sensitivity and specificity of the skin-gas cam to EtOH vapor enabled the detection of partially different concentrations of TrEtOH between the palm and wrist (Fig. 1c). Spatiotemporally higher concentrations of TrEtOH were frequently observed at the palms than the wrists, which seemed to be related to sweating,. It is known that the density of sweat gland, which reacts not only to thermal stimuli but also to mental stimuli, is higher in a palm than a wrist [3]. We are now also working on simultaneous measurements of sweating and TrEtOH to better understand this initial finding. Conclusions Biofluorometric real-time imaging of transcutaneously emitted EtOH vapor was achieved by the developed skin-gas cam system based on the ADH-immobilized cotton mesh sensor. The spatiotemporal change of EtOH vapor concentration was measured quantitatively. Under the time-domain image differential analysis, the response time was 30 sec. Furthermore, the skin-gas cam showed sufficient sensitivity (0.02–300 ppm) and high selectivity to TrEtOH for practical use. Finally, the time and site-specific emission profile of TrEtOH was obtained from subjects who took alcohol. Measurement other VOCs such as acetaldehyde, acetone, and 2-propanol is the next target to realize non-invasive disease screening and assessment of metabolism.

A cantilevered piezoelectric energy harvester excited by an axially pushed wedge cam using repulsive magnets for rotary motion

Harvesting energy from the rotary environment to replace the conventional electrochemical batteries has gained considerable interest. Different from the existing rotation-induced energy harvesters based on the bidirectional deformation of piezoelectric vibrators, a novel cantilevered piezoelectric energy harvester excited by an axially pushed wedge cam using repulsive magnets for rotary motion was presented and fabricated in this paper. The new piezoelectric rotary energy harvester (PREH) was characterized by the simultaneous realization of unidirectional deformation and limited amplitude for piezoelectric vibrators. To verify the feasibility of the proposed principle and design, a theoretical model was established based on Fourier series as well as superposition principle. Meanwhile, the influence of the system parameters on the response characteristic of the presented PREH were obtained by simulation. And then, the experiments of rotating speed response were performed to evaluate the energy harvesting performance in terms of the deformation and open-circuit voltage. Both simulation and experimental results showed that the amplitude of the piezo-cantilever could be limited by using the cam mechanism and there were obvious resonance peaks on the amplitude-rotary speeds curves. Thus, the relatively stable output voltage could be maintained over a broad rotating speed range. Also, the stable voltage increased with the increasing of cam lift, but the effective rotating speed range became narrow. With the increasing of the cam angle, the effective rotating speed bandwidth could be increased, whereas the self-locking phenomenon of the piezo-cantilever would occur when the angle was increased to some extent. Besides, the bandwidth could be adjusted by changing the number of exciting magnets and stiffness of cam system. Under the optimum matching parameters, the maximum power 10.88 mW was reached for the presented PREH.

Implementation of integrated design systems in the learning process

The modern stage of development of CAD-systems is characterized by a significant expansion of the scope of their use. An interesting direction for improving CAD systems is their integration with CAM systems. One of the main tasks solved by CAM systems is the development of control programs for CNC machines. Many software developers for automation of design and technological preparation of production have already equipped their systems with appropriate modules. These circumstances pose an urgent task for higher educational institutions to introduce the study of integrated CAD/CAM systems into the educational process of training design engineers. In this case, the emphasis should be placed on the practical mastery of the skills of developing control programs using a 3D-model of the manufactured part. The stages of preparation for the implementation of the system are described, starting with the analysis of the market of necessary software products and ending with the adaptation of the licensed system to the conditions of use in the educational process of the university. A link is given to the description of the methodology used in the assessment of automated systems at the stage preceding the tender for their purchase. It is emphasized that the study of the possibility of using a CAD/CAM system in the preparation of design engineers was carried out by students during the course and diploma projects in the discipline “Automated systems for technological preparation of production”. The methodology for designing control programs used by students is given, and the results obtained are assessed.

Analysis of Subject Areas in Preproduction and Shop-Floor Planning

Ontological aspects of subject fields in preproduction systems (CAM and CAPP systems) and shop-floor planning systems (MES systems) are outlined, with a view to subsequent integration of corporate applications at the semantic level. The subject area of CAM systems is found to be a component of the subject area of CAPP systems, while the ontology of CAPP systems and MES systems largely intersects with technological concepts. Preproduction systems and shop-floor planning systems provide the information contexts that must be taken into account in integrating corporate applications.

A Review on Efficacy of Siddha Medicinal Herbs as Antiviral Drugs against COVID-19

In a very short time, the Coronavirus disease (COVID-19) caused by the SARS-CoV-2 virus, has become a global pandemic. It has infected about 29,155,581 patients and brought forth death rate about 926,544 among 216 countries as recorded by World Health Organization on 15th September 2020. At present, there is no specific and direct treatment or vaccine for this infectious disease. No therapeutic options available to cure the infection in till date which increases the mortality rate across the countries. Currently there is no antiviral treatments have been approved, several approaches have been proposed in western medicine, Chinese medicine, CAM, AYUSH and other systems. Siddha Herbal medicines are achieving high attention because of the extensive therapeutics like potent anti-microbial, immunomodulatory, anti-inflammatory, and antioxidant properties. Ministry of AYUSH, Govt. of India recommended 12 Siddha herbals (Inji – Zingiber officinale, Thulasi – Ocimum sanctum, Milaku – Piper nigrum, Karunjeeragam – Nigella sativa, Keezhanelli – Phyllanthus niruri, Adhimathuram – Glycyrrhiza glabra, Vellaippoondu – Allium sativum, Citramutti – Sida cardifolia, Seenthil – Tinospora cordifolia, Manjal – Curcuma longa, Elumitchai – Citrus lemon and Vembu – Azadirachta indica) for the prevention by enhancing immunity as well as for the management of this infectious disease in its recent official publication ‘Guidelines for Siddha Practitioners for COVID 19’. This is the common advisory and the anti-viral activity of these herbals against COVID 19 is not established yet. The current situation demands proper herbal drug utilization to prepare the population immunity to fight against the infection. The present review spotlight on the literature review and the review of pharmacological actions of these herbals.

Energy-Saving Trajectory Planning for Robotic High-Speed Milling of Sculptured Surfaces

In the field of sculptured surfaces machining, the robot trajectory planning, under high-order complex constraints, aiming at minimizing energy or time, is always a challenge. The complexity of curvature characteristics of sculptured surfaces and the nonlinearity of relevant constraints are the main reasons. This article proposes an efficient planning method of minimum-energy robot trajectory, for high-speed machining of sculptured surfaces. First, the energy characteristic model of the robot machining system (RMS) is established, to acquire the energy-optimal feedrate, under velocity constraints, to use in the subsequent trajectory planning. Next, a trajectory planning model, with complex constraints, is developed. The proposed method transforms the original trajectory planning into a minimal modification of the initial objective-optimal B-spline feedrate curve (BFC). Furthermore, two main coupling problems, which influence the minimal change of curves, in the direct evolution-based BFC modification, are addressed. Based on the derived solutions, a novel modification algorithm of BFC, with a callback mechanism (CBM), is proposed. Finally, the performance of the proposed method and the specific algorithm is validated by two case studies. Results show that the proposed method can significantly improve the efficiency of robot trajectory planning, aiming at minimum energy, while exhibiting excellent performance. <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">Note to Practitioners</i> —This work was motivated by how to automatically and effectively acquire the energy-saving trajectory of a robotic system, executing sculptured surface machining. This article suggests a new approach that transforms the original trajectory optimization into a minimal modification of the initial energy-optimal BFC, obtained under velocity constraints. This approach calculates the complex energy formula only once. A CBM, for constraint-based BFC modification, is proposed, to revise the redundant reduction of the feedrate. The proposed modification algorithm significantly decreases the detrimental effect of two coupling problems, on the adjustment of the BFC. Results show that the computational efficiency of the proposed method is significantly superior to the one of the direct optimization method. The performance of the proposed modification algorithm is obviously advanced compared to the existing B-spline evolution algorithm. In blade machining, after optimizing the trajectory using the proposed method and algorithm, both energy and time decrease by more than 45% compared to the conservative feed. The proposed algorithm improves significantly the trajectory compared to the prior art algorithm. Technologists benefit from reduced planning time and improved machining performance. However, incorporation into a CAM or manufacturing system has not yet been realized and remains a significant work to be done in the future.

The Influence of Automated Machining Strategy on Geometric Deviations of Machined Surfaces

This paper deals with various automated milling strategies and their influence on the accuracy of produced parts. Among the most important factors for surface quality is the automated milling strategy. Milling strategies were generated from two different programs, CAM system SolidCAM, with the help of workshop programming in the control system Heidenhain TNC 426. In the first step, simulations of different toolpaths were conducted. Using geometric tolerance is becoming increasingly important in robotized production, but its proper application requires a deeper understanding. This article presents the measurement of selected planes of robotized production to evaluate their flatness, parallelism and perpendicularity deviations after milling on the coordinate measuring machine Carl Zeiss Contura G2. Total average deviations, including all geometric tolerances, were 0.020 mm for SolidCAM and 0.016 mm for Heidenhain TNC 426. The result is significantly affected by the flatness of measured planes, where the overlap parameter of the tools has a significant impact on the flatness of the surface. With interchangeable cutter plate tools, it is better to use higher overlap to achieve better flatness. There is a significant difference in production time, with SolidCAM 25 min and 30 s, and Heidenhain 48 min and 19 s. In accordance with these findings, the SolidCAM system is more suitable for production.

Evidence that short-period AM CVn systems are diverse in outburst behaviour

ABSTRACT We present results of our analysis of up to 15 yr of photometric data from eight AM CVn systems with orbital periods between 22.5 and 26.8 min. Our data have been collected from the GOTO, ZTF, Pan-STARRS, ASAS-SN, and Catalina all-sky surveys and amateur observations collated by the AAVSO. We find evidence that these interacting ultracompact binaries show a similar diversity of long-term optical properties as the hydrogen accreting dwarf novae. We found that AM CVn systems in the previously identified accretion disc instability region are not a homogenous group. Various members of the analysed sample exhibit behaviour reminiscent of Z Cam systems with long superoutbursts (SOs) and standstills, SU UMa systems with regular, shorter SOs, and nova-like systems that appear only in a high state. The addition of TESS full frame images of one of these systems, KL Dra, reveals the first evidence for normal outbursts appearing as a precursor to SOs in an AM CVn system. Our results will inform theoretical modelling of the outbursts of hydrogen deficient systems.

KEY INFORMATION AND COMMUNICATION TECHNOLOGIES AS AN IMPORTANT FACTOR IN IMPROVING THE EFFICIENCY OF SUPPLY CHAINS IN THE FASHION INDUSTRY

The article considers key information and communication technologies used in the supply chains of the fashion industry. The author segmented these technologies into several groups, including selected programs that ensure effective communication between the company’s functional departments and supply chain links; software resources aimed at maintaining logistics operations, such as production, warehousing, cargo transportation; operational and strategic planning systems. The main purpose of the considered information technologies is to take into account the specific characteristics of the “fashion” business, such as a high range and a short product life cycle, the need to take into account the rapidly changing requirements of buyers of goods in the fashion industry, the geographical distribution of supply chain participants. The author performs a review of key software products and technologies that improve the efficiency of business process management in the supply chains of the fashion industry, including CAD and CAM systems, ERP systems on the example of SAP AFS, SAP Fashion Management and some other software resources and technologies.

Influence of dimension chains on product assembly sequences

The paper considers the influence of design dimension chains on the assembly sequence of a complex product. When assembling products, the rule of connectivity of the dimension chain must be followed. For this reason, the dimension chain induces a binary partial order relation on the set of product parts. The assembly sequences for which the connectivity rule is applied are linear extensions of this order relation. The number of the linear extensions for the orders generated by the main methods of dimensioning is calculated. It is shown that the chain method of dimensioning is the most rigid, and the coordinate method is the most “tolerant”. The combined method occupies an intermediate position. The principle of matching the dimension and mechanical structures of a complex product is proposed. The results obtained can be used to generate rational dimension schemes in integrated CAD / CAM systems.

Automation of preproduction processes for high-precision small-sized parts on CNC machines

The theoretical basis of the processes of preparation for the production of high-precision small-sized parts of coaxial radio components on CNC machines allows you to supplement the existing CAD / CAE / CAM with fragments of algorithmizing. To integrate the stages of technological preparation for the production of high-precision small-sized parts of coaxial radio components on CNC machines, a study of the features of the production of parts and the standard functionality of CAM systems was carried out. A classification of these parts by the type of equipment, types, serial production, variable parameters within the type, materials, and tools has been developed. The possibilities of the extensibility of the functions of CAM systems, the existing methods of creating and verifying control programs are considered. An example of a successful expansion of the functionality of a standard CAM system in the radio-electronic industry is given - a module for increasing machining accuracy with a constant cutting mode by optimizing the mutual positioning of the tool and the workpiece. Requirements have been developed for the creation of a specialized combined method for verification of control programs using all existing verification capabilities and minimal use of debugging and verification directly on the machine with the maintenance of reference books of worked processing modes in which the number and size of burrs are minimal, as well as a library of control programs equipped with a search system for the parameters of the difference in the execution of parts.

New algorithm to calculate the cutter location points (CL) optimizing the chordal tolerance for 2 ½ axis milling of free form surfaces

Even though the high order polynomial can be used to describe a free form tool path for CNC milling, traditional linear interpolation (G01) is the most used today. As investigated in a previous work, different CAM systems calculate different points (CC) to mill the same surface under the same tolerance and cutting conditions. The current work presents a new approach to generate NC codes optimizing the use of the chordal tolerance for 2½ milling. The experimental results shown that the NC codes generated by the proposed method reduced in about 60% the milling time by reducing the CC points, without losing the accuracy.

An update on CAD/CAM removable complete dentures: A review on different techniques and available CAD/CAM denture systems

(Times New Roman, 10, Bold) This article describes the different techniques and CAD/ CAM denture systems that are available. The fabrication of removable complete dentures by CAD/ CAM systems reduces chair side time and also number of appointments. If the dentures are lost or broken, it can be refabricated from the records saved digitally. The different CAD/ CAM denture systems evaluated in this article are AVADENT, the Whole You Nexteeth system, Ceramill Full Denture system, Baltic denture system and Wieland denture system and VITA VIONIC system. These systems differ in the number of appointments and the try in options provided by each of them.

A dual cam system for four-bar motion generation with adjustable length crank and follower links

A dual cam system for four-bar motion generation with adjustable length crank and follower links