Abstract Objective  This study investigated biomechanical behavior of custom post core made of six different materials on the tooth with and without the ferrule under different occlusal load. Materials and Methods  Three-dimensional models of mandibular first premolar, with and without ferrule, reconstructed from micro-computed tomography image are restored with different custom post core and zirconia crowns. By using the finite element analysis, von Mises stress shown in MPa was measured under simulated axial and oblique load of 200 [N]. To compare the stress distribution, six different custom post core materials were chosen: zirconia, Ni-Cr alloy, gold alloy, glass fiber-polyether ether ketone, polyether ether ketone, and carbon fiber-polyether ether ketone. Results  Custom post cores with a higher modulus of elasticity showed higher measured stress in the posts, but less stress in dentin. Measured stress in custom post core under oblique loading was approximately three times higher compared with axial loading. Stress in custom post core and in dentin under both types of loads was slightly higher in teeth without ferrule effect. Conclusion  The use of custom cast post cores made of different alloys is recommended in restoration of endodontically treated teeth, with extensive loss of tooth structure especially in teeth without ferrule effect.

Analysing of material flows within the boundaries of the production system it is possible to conclude that the sources and sinks of those material flows are storages. In those storages in the function of the kind and the type numerous processes are implemented. These storage processes along with the material handling processes are responsible for quantitative and dynamic balancing of material flows and as such have a significant impact on the total cost and productivity of the production system. Due to the above reasons, the design of storage is an important task which needs to be adequately accessed. Regardless of the kind and the type and the associated processes within storage one of the main activities in the design phase of storage is to define its location, with special emphasis on interaction with other elements of the production system (production and processing equipment, material handling equipment and devices, etc.). Namely, selection of the right location, among other things ensuring the necessary conditions which will make the process of storage to meet the technical and technological, economic, organizational, IT and other requirements upon it.

Today’s business of manufacturing systems is entirely dictated by the dynamics of the market and every day there is a need for adjustment of the structure and parameters of associated manufacturing systems. Those adjustments should ensure the operation of manufacturing systems in more favourable manufacturing and economic conditions, and often this process is directly linked with the starting of investment process. On the other hand, every day practice proves that evaluation of investment program during selection of structure of manufacturing system with the aim to accomplish production plans and reduction of production costs is often based on insufficient sets of information. Lack of information may result in inappropriate insight into overall techno-economic effects that can be achieved by investment program. Within this paper are presented researches which resulted in development of a new systematic approach in the analysis of potential structures and parameters of manufacturing systems with the aim to plan, project or reengineer manufacturing systems on the basis of minimal production costs.

Introduction: An abfraction lesion is a type of a non-carious cervical lesion (NCCL) that represents a sharp defect on the cervical part of tooth, caused by occlusal biomechanical forces. The largest prevalence of the NCCL is found on the mandibular first premolar. The goal of the study is, by means of a numerical method – the finite element method (FEM), in an appropriate computer program, conduct a stress analysis of the mandibular premolar under various static loads, with a special reference to the biomechanics of cervical tooth region. Material and methods: A three-dimensional model of the mandibular premolar is gained from a µCT x-ray image. By using the FEM, straining of the enamel, dentin, peridontal ligament and alveolar bone under axial and paraxial forces of 200 [N] is analyzed. The following software were used in the analysis: CT images processing–CTAn program and FEM analysis–AnsysWorkbench 14.0. Results: According to results obtained through the FEM method, the calculated stress is higher with eccentric forces within all tested tooth tissue. The occlusal load leads to a significant stress in the cervical tooth area, especially in the sub-superficial layer of the enamel (over 50 MPa). The measured stress in the peridontal ligament is approximately three times higher under paraxial load with regard to the axial load, while stress calculated in the alveolar bone under paraxial load is almost ten times higher with regard to the axial load. The highest stress values were calculated in the cervical part of the alveoli, where bone resorption is most commonly seen. Conclusion: Action of occlusal forces, especially paraxial ones, leads to significant stress in the cervical part of tooth. The stress values in the cervical sub-superficial enamel layer are almost 5 times higher in relation to the superficial enamel, which additionally confirms complexity of biomechanical processes in the creation of abfraction lesions.

This paper deals with combination of two modern engineering methods in order to optimise the shape of a representative casting product. The product being analysed is a sling, which is used to attach pulling rope in timber transportation. The first step was 3D modelling and static stress/strain analysis using CAD/CAE software NX4. The slinger shape optimization was performed using Traction method, by means of software Optishape-TS. To define constraints for shape optimization, FEA software FEMAP was used. The mould pattern with optimized 3D shape was then prepared using Fused Deposition Modelling (FDM) Rapid prototyping method. The sling mass decreased by 20%, while signifficantly better stress distribution was achieved, with maximum stress 3.5 times less than initial value. The future researches should use 3D scanning technology in order to provide more accurate 3D model of initial part. Results of this research can be used by toolmakers in order to engage FEA/RP technology to design and manufacture lighter products with acceptable stress distribution.

One of the main driving forces of manufacturing companies is continuous need for short-term development of new products and decrease of expenses, so that profitability and competition is maintained. Rapid Prototyping Technologies provide that bridge from product conceptualization to product realization in reasonably fast manner, without the fuss of NC programming, jigs and fixtures. The process of Three Dimensional Printing 3DP, which is based on original MIT 3DP technology (Massachusetts Institute of Technology –MIT) and improved by Z Corporation, nowadays it is intruded in direct and indirect parts manufacturing regardless its level of complexity. This RP process offers very good ratio between used materials, price, application and a quality of printed models. Main driving factors in a real-life application of the printed models are their mechanical properties, dimensional precision and surface texture quality. In this paper we are presenting research of the effects of process parameters and post processing on the tensile strength of three-dimensional printed models.

Proces 3D printanja kao i sve Rapid Prototyping tehnologije koje svoj rad zasnivaju na oblikovanju "slobodne forme" okarakterizirane su u vecoj ili manjoj mjeri određenim stepenom odstupanja proizvedenih dijelova od polaznog 3D CAD modela. U cilju determiniranja velicine odstupanja u radu je izvrsena analiza dimenzionalne tacnosti prototipova zasnovanih na bazi skroba i gipsa proizvedenih procesom 3D printanja, kao i analiza troskova proizvodnje istih.