Computer Engineering Complete Dentures Workflow: Systematic Techniques Review

Background: The progress in the use of computer-aided design/computer aided manufacturing (CAD/CAM) to fabricat removable prosthodontic prostheses in dental clinics has been exponential. Commercially existing CAD/CAM denture techniques grow every year with increasing benefits to dentists and patients. Study Design: Systematic review. Aims: This review assessed and evaluated the different clinical production protocols of presently accessible CAD/CAM denture systems that offer decision support for dental practitioners. Methodology: Data for the current object were collected by surveys from different companies manufacturing the Computer Engineering Complete Denture (CECDs). All related subjects published at the last 10 years were collected and included in this review. Techniques were arranged in alphabetical order, as follows. AvaDent Digital Dentures (Global Dental Science), Baltic Denture Creator System (Merz Dental GmbH), and Ceramill Full Denture System (Amann Girrbach AG) can manufacture denture fabrication in three visits, including a try-in step. DENTCA Digital Dentures (Whole You Nexteeth, Inc) can also perform this in three visits. The Wieland Digital Denture (Ivoclar Vivadent, Inc) can manufacture in four dental appointments. Recently developed VITA VIONIC Digital System (VITA Zahnfabrik, Bad Säckingen, Germany) can perform two-step CECD manufacturing. Results: Most of the systems involved subtractive manufacturing for the fabrication of their dentures and only closed systems. However, Baltic Denture System and VITA VIONIC material types are an open structure that allow users to choose among different handling protocols. It can be shared with several unclosed digital scanner, CAD software options, and milling machines. Conclusions: The six existing CECD fabrication systems offer many advantages. The decision on which technique to use may be contingent on the dentist’s prosthodontic expertise, patient output amount, and requirements concerning denture individualization.

New Approach to Three-Coordinate Milling of Large-Sized Surfaces of Second Order

The study introduces a new approach to precision machining of large-sized surfaces of second order on a three-coordinate horizontal milling machine. The new technology does not require the use of unique large-size boring lathes or five-axis milling machines. Three-axis horizontal milling machines do not need to be equipped with additional equipment that provides the workpiece with the missing rotational and translational movements relative to the machine table. The proposed technology is based on the use of a new approach that combines the geometric parameters of the second-order machined surface, the spherical surface of the cutting tool, i.e. cutter, and their position relative to the working table. The use of the developed technology will improve the efficiency and accuracy of machining the surface of second order, as well as simplify the control program and technological support due to the absence of movable equipment. The study gives an example of practical implementation and shows the possibility of independent control of the machined parabolic surface geometry using a three-coordinate horizontal milling machine.

Development of a Cost Model for Vertical Milling Machines to Assess Impact of Lightweighting

Lightweighting is a design strategy to reduce energy consumption through the reduction of mass of a product. Lightweighting can be applied to machine tools to reduce the amount of energy consumed during the use phase. Thus, the energy cost of machine operation will be reduced. One might also hypothesize that since a lighter-weight machine tool requires less material to build, the cost to produce such a machine will be less. However, it may also be the case that lightweighting a machine tool increases its complexity, which will likely drive up the cost to manufacture the machine. To explore the cost drivers associated with building a machine tool, data on the features associated with a wide variety of vertical milling machine tools are collected. Then, empirical cost models are fit to this data. The results from the cost models show that the machine tool mass is a significant cost driver; other key drivers are the number of axes and spindle power. The models are used to predict the cost benefits of lightweighting in terms of mass, which are compared to potential increased manufacturing costs associated with complexities introduced due to lightweighting.

Wear Resistance, Color Stability and Displacement Resistance of Milled PEEK Crowns Compared to Zirconia Crowns under Stimulated Chewing and High-Performance Aging

Recently, polyetheretherketone (PEEK) has been introduced to the dental market as a high-performance and chemically inert biomaterial. This study aimed to compare the wear resistance, abrasiveness, color stability, and displacement resistance of zirconia and PEEK milled crowns. An ideal tooth preparation of a first maxillary molar was done and scanned by an intraoral scanner to make a digital model. Then, the prosthetic crown was digitally designed on the CAD software, and the STL file was milled in zirconia (CaroZiir S, Carol Zircolite Pvt. Ltd., Gujarat, India) and PEEK (BioHpp, Bredent GmbH, Senden, Germany) crowns using five-axis CNC milling machines. The wear resistance, color stability, and displacement resistance of the milled monolithic zirconia with unfilled PEEK crowns using a chewing simulator with thermocyclic aging (120,000 cycles) were compared. The antagonist wear, material wear, color stability, and displacement were evaluated and compared among the groups using the Wilcoxon–Mann–Whitney U-test. Zirconia was shown to be three times more abrasive than PEEK (p value < 0.05). Zirconia had twice the wear resistance of PEEK (p value < 0.05). Zirconia was more color stable than PEEK (p value < 0.05). PEEK had more displacement resistance than zirconia (p value < 0.05). PEEK offers minimal abrasion, better stress modulation through plastic deformation, and good color stability, which make it a promising alternative to zirconia crown.

Physical and mathematical model of rock destruction by a milling machine cutter

As a result of the analysis of the work on rock destruction by cutters of milling of machines, it was found that the existing developments do not allow us to proceed to the derivation of calculation d dependencies for determining fracture resistance, or can be used only in preliminary calculations of the known by design parameters of milling machines. To eliminate these disadvantages, a combined physical and mathematical model of the process of interaction of a single milling cutter with a spherical tip with the rock has been developed. Consideration of the physical picture of the action of forces and stresses acting from the cutter with spherical tips on the separating rock element in the limiting condition allowed to describe analytically the components of total resistance, which are the mathematical part of the physical and mathematical model of rock destruction by cutters. Analytical dependences for determining the tangential and normal components of fracture resistance of rocks of medium hardness have been obtained. The adequacy of the physical and mathematical model to the physical process of destruction of rocks of different hardness by cutters on a universal stand was tested both in the field and in the laboratory conditions. Technical evaluation of the results of experimental studies confirms the reliability of the developed physical and mathematical model.

Analisis Akuntansi Biaya Produksi Mesin Dengan Metode Full Costing Dalam Menetapkan Harga Pokok Produksi Mesin Pada PT. Cahaya Agro Teknik Surabaya

The purpose of this study was to determine the extent to which the calculation of the cost of production using the full costing method the determine the cost of production at PT.Cahaya Agro Teknik Surabaya. Researchers used data sources consisting of primary data consisting of primary data and secondary data. The secondary theory is the theory obtained from the existing literature theory data, while the primary data is obtained from the company PT. Cahaya Agro Teknik Surabaya. In this study, the researcher used descriptive method with a qualitative method approach. Descriptive research method is research on problems that occur in the company and qualitative method is a research procedure that produces descriptive data consisting of written or oral forms of people and behaviors that researchers observe. The tools used for research use the full costing method. The researchers use the full costing method because the full costing method is one method of determining the costs of production that takes into account all elements of production costs into the costs of production. The results of the research that researchers have done are in calculating the cost of production using the full costing method to produce a higher value than the method applied by PT. Cahaya Agro Teknik Surabaya. This is because PT. Cahaya Agro Teknik Surabaya does not fully calculate the costs, both variable and fixed. The results of the analysis in calculating the cost of production using the full costing method for plastic 50 miliing mechines amounting to Rp.170.723.300, plastic 100 milling machines of Rp.300.976.260, plastic 200 milling mechines of Rp .509.424.300 and coconut milk machine of Rp. 169.424.300 Keywords: Full Costing Method, Cost of Production, Analysis Tujuan penelitian ini adalah untuk mengetahui sejauh mana perhitungan harga pokok produksi dengan menggunakan Metode full costing untuk menetapkan harga pokok produksi pada PT. Cahaya Agro Teknik Surabaya. Peneliti menggunakan sumber data yang terdiri dari data primer dan data sekunder. Teori sekunder adalah teori yang diperoleh dari data kepustakaan yang ada, sedangkan data primer diperoleh dari perusahaan PT. Cahaya Agro Teknik Surabaya.Dalam penelitian ini peneliti menggunakan Metode diskriptif dengan pendekatan Metode kualitatif. Metode penelitian kualitatif deskriptif adalah penelitian terhadap masalah yang terjadi diperusahaan dan Metode kualitatif adalah prosedur penelitian yang menghasilkan data secara deskriptif yang terdiri dari kata bentuk tertulis atau lisan dari orang-orang yang peneliti amati. Alat yang digunakan untuk penelitian menggunakan Metode Full Costing karena Metode penentuan harga pokok produksi yang memperhitungkan semua unsur biaya produksi ke Dalam harga pokok produksi.Hasil peneliti yang telah peneliti lakukan adalah Dalam perhitungan harga pokok produksi dengan menggunakan Metode full costing menghasilkan nilai yang lebih tinggi dibandingkan dengan Metode yang diterapkan oleh PT.Cahaya Agro Teknik Surabaya. Hal ini dikarenakan PT.Cahaya Agro Teknik Surabaya tidak sepenuhnya melakukan perhitungan harga pokok produksi baik yang bersifat variable maupun tetap. Hasil analisis Dalam perhitungan harga pokok produksi menggunakan Metode full costing untuk mesin giling plastic 50 sebesar Rp 170.723.300, Mesin Giling Plastik 100 sebesar Rp 300.976.300, Mesin Giling Plastik 200 Sebesar Rp 509.424.300 dan mesin peras santan sebesar Rp 169.424.300. Kata Kunci: Metode Full Costing, Harga Pokok Produksi, Analisis

Trochoidal Milling Path with Variable Feed. Application to the Machining of a Ti-6Al-4V Part

Trochoidal milling is a well-stablished machining strategy which still allows for the introduction of new approaches. This strategy can be applied to any kind of material, although it is usually associated to advanced materials, such as titanium and nickel alloys. This study is based on the adaptation of the feed speed of a milling tool with Ti-6Al-4V, so the chip width can be maintained constant without modifying the path geometry. A singularity in the experimental stage was to mill an Archimedes spiral groove instead of the conventional straight grooves. This made it possible to obtain a concave wall as well as a convex one and to optimize the amount of material used. The time efficiency compared to a constant feed, was slightly superior to 20%, reducing tool wear also. These techniques require milling machines with high mechanical and kinematic performance, as well as the absence of clearance between joints and a high acceleration capacity.

FIBER REINFORCED ASPHALT

Asphalt can be considered a particulate composite with almost no tensile strength, that is, the only physical link between the matrix (bitumen) and the particles (gravel) is the cohesive strength of the bond itself and the aggregate simply breaks away from the binder under any number of tension-based loads such as earth shifts, heavy loads, and even moisture. Over the course of a few months, these breaks lead to larger cracks, potholes, and damaged entire road sections that require significant investment much earlier than the expected 15-year lifecycle. Increasing the strength and modulus of asphalt can improve its durability, extend its lifespan, and reduce its maintenance costs. However, as most asphalt is usually recycled during rehabilitation, improving strength cannot come at the expense of the existing infrastructure support system, i.e., materials and technologies should be compatible with road resurfacing equipment and practices. Short composite fibers have high modulus and strength but are easily broken up by road milling machines, making them ideal candidates to mix into the asphalt during rehabilitation. Additionally, by deliberately limiting the fiber size, this will have a major ancillary benefit for the environment: allowing the use of off-fall composite scraps from the manufacturing sectors that are often chopped and relegated to landfills. This investigation examines the material behavior from both experimental and numerical perspective on the inclusion of short fibers for reinforcing asphalt, creating a dual fiber and particle composite material system. Asphalt by its very nature is a relatively soft material with high strains until failure under some conditions, and brittle under others, making this a complex material system combining both hyperelastic and elastic-brittle response. Validation studies are examined for this unique material under various quasi-static to dynamic loading rates to create a material system for extended finite element analysis in improved infrastructure designs.