• Restorative Dentistry and Endodontics
• /
• v.38 no.3
• /
• pp.134-140
• /
• 2013

Objectives: There has been a growing interest in glass ceramic systems with good esthetics, high fracture resistance and bonding durability, and simplified fabrication techniques using CAD/CAM. The aim of this study is to compare flexural strength before and after heat treatment of two lithium disilicate CAD/CAM blocks, IPS e.max CAD (Ivoclar Vivadent) and Rosetta SM (Hass), and to observe their crystalline structures. Materials and Methods: Biaxial flexural strength was tested according to ISO 6872 with 20 disc form specimens sliced from each block before and after heat treatment. Also, the crystalline structures were observed using field-emission scanning microscopy (FE-SEM, Hitachi) and x-ray diffraction (XRD, Rigaku) analysis. The mean values of the biaxial flexural strength were analyzed by the Mann-Whitney U test at a significance level of p = 0.05. Results: There were no statistically significant differences in flexural strength between IPS e.max CAD and Rosetta SM either before heat treatment or after heat treatment. For both ceramics, the initial flexural strength greatly increased after heat treatment, with significant differences (p < 0.05). The FE-SEM images presented similar patterns of crystalline structure in the two ceramics. In the XRD analysis, they also had similar patterns, presenting high peak positions corresponding to the standard lithium metasilicate and lithium disilicate at each stage of heat treatment. Conclusions: IPS e.max CAD and Rosetta SM showed no significant differences in flexural strength. They had a similar crystalline pattern and molecular composition.

• 제어로봇시스템학회:학술대회논문집
• /
• 1993.10a
• /
• pp.1024-1030
• /
• 1993

In manufacturing press die with free surface, grinding operation is an important post process for surface finish and dimensional accuracy. With the advancement of NC technology. surface grinding operation is increasingly replaced by the gantry type manipulator. As the mechanics for grinding operation is different from machining operation, conventional CAM system for machining operation is hard to apply. In this. paper, we develop a five-axis CAM system by which an efficient gantry trajectory can be planned and verified. The developed system consists of four conceptual modules; namely CAD, PROCESS. CAM, and ANALYSIS. In the CAD module, the machined surface is represented by CL-data or surface modeler, and process parameters are specified by the PROCESS module. Then, the CAM module generates a series of grinding paths based on the grinding mechanics together with process databases for tool spaces and grinding conditions. The generated paths are verified via ANALYSIS module. Validation via real experiments is left for further study.

• International Journal of CAD/CAM
• /
• v.6 no.1
• /
• pp.167-172
• /
• 2006

Recently, wire-EDM became a necessity for many engineering applications, particularly in the dies making. No-Core cut process is helpful for operations in which falling slug can jam the machine or wire. In this paper a proposed CAM system (called NCPP) is introduced, to overcome the limitations of the existing CAM systems in the machining of No-Core cut. The proposed CAM system (NCPP) provides pocketing of No-core cut and optimal selection of the position of starting hole (wire threading point), to minimize toolpath length. It was written for data exchange between CAD-CAM-CNC machines. This data model will become part of the ISO (Data model for Computerized Numerical Controllers) international standard. The NCPP system has been implemented in Visual C++. Many examples are used to illustrate NCPP system. The results show that, NCPP saves the machining time by significant value. This value depends on the shape and complexity of the workpiece that is being cut.

• Korean Journal of Computational Design and Engineering
• /
• v.10 no.4
• /
• pp.254-261
• /
• 2005

The purpose of this research is to develop a method for cutting non-circular holes on a bent thick plate. Generally in order to cut the holes on the large plates, a special-purpose 5-axis machine is needed. However, such a machine is unavailable in most of the machine shops. This paper provides a description of such a method that utilizes a general-purpose 5-axis water-jet machine in place of the special-purpose machine: First, the bent piece is transformed into a flat plate, where the shape of the holes is reconstructed by considering deformation during bending. Then, after a 5-axis NC data is generated, the holes on the flat plate are cut using the 5-axis water-jet machine. The final step is to return to its, original shape by bending the plate with its newly-cut holes. The proposed methodology is implemented as a dedicated system by customizing a commercial CAD/CAM system. Some illustrations are provided throughout the paper in order to show the validity of the proposed methods and the developed system.

• Journal of Technologic Dentistry
• /
• v.42 no.3
• /
• pp.228-233
• /
• 2020

Purpose: This study aimed to assess and compare the marginal fit of ceramic-based hybrid resin restoration (HYB) and zirconia restoration (ZIR) for dental computer-aided design/computer-aided manufacturing systems. Methods: A stainless steel master model was produced. The impression was first made with silicone, and then stone working models were produced. A total of twenty restorations were fabricated with two different materials: ZIR and HYB. The silicone film thickness of the marginal gap was measured using a digital microscope; digital photos were taken at a magnification of ×160, and then analyzed using a measurement software. The values of the result were evaluated with the independent-sample t-test (α=0.05). All statistical analyses were performed with a statistical software. Results: The mean values for the marginal gap was 37.14±2.96 ㎛ for HYB, compared with 40.37±5.26 ㎛ for ZIR. No significant difference was found between ZIR and HYB (p=0.107). Conclusion: As a result, the marginal fit of the restoration fabricated using the hybrid resin was better than that of the restoration fabricated using zirconia. Also, the marginal fit of all groups was below the clinical acceptable range of 120 ㎛. Thus, HYB for dental CAD/CAM system in this study is expected to be suitable for clinical use in dentistry.

• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.9 no.3
• /
• pp.569-573
• /
• 2008

In this thesis, the drawing was prepared for the strip layout of the pickup frame In the press die, the drawing for press layout is a major factor in determining the mass production of the product. The 3D CAD/CAM system was applied to easily correct interference factors with other parts to be mounted. This study improved the material utilization ratio to 28.49% by optimizing the blank layout and strip layout in wide-width arraying. The 3D CAD/CAM software used is Unigraphics NX 4.0, and the strip layout drawing was prepared in 12 processes.

• Journal of the Korean Society for Precision Engineering
• /
• v.13 no.3
• /
• pp.158-164
• /
• 1996

In this paper, the CNC cutting planning module for product with three dimensional solid shape is realized to develop a smart CAD/CAM system which performs systematically from the shape design of procuct by the B-Rep solid modeler to the CNC cutting of product by a machining center. The three dimensional solid shape of product can be easily designed and constructed by the Euler operators and Boolean operators of the solid modeler. And the various functions such as the automatic generation of tool path for the rough and finish cutting processes, the automatic elimination of overcut, the automatic generation of CNC code for the machining center and do on, are established. Especially, the overcut-free tool paths are obtained by splitting the CL solid which is composed of the offset surfaces of the solid shape of product.

• Restorative Dentistry and Endodontics
• /
• v.49 no.3
• /
• pp.32.1-32.12
• /
• 2024

From the restorative perspective, various methods are available to prevent the progression of non-carious cervical lesions. Direct, semi-direct, and indirect composite resin techniques and indirect ceramic restorations are commonly recommended. In this context, semi-direct and indirect restoration approaches are increasingly favored, particularly as digital dentistry becomes more prevalent. To illustrate this, we present a case report demonstrating the efficacy of hybrid ceramic fragments fabricated using computer-aided design (CAD)/computer-aided manufacturing (CAM) technology and cemented with resin cement in treating non-carious cervical lesions over a 48-month follow-up period. A 24-year-old male patient sought treatment for aesthetic concerns and dentin hypersensitivity in the cervical region of the lower premolar teeth. Clinical examination confirmed the presence of two non-carious cervical lesions in the buccal region of teeth #44 and #45. The treatment plan involved indirect restoration using CAD/CAM-fabricated hybrid ceramic fragments as a restorative material. After 48 months, the hybrid ceramic material exhibited excellent adaptation and durability provided by the CAD/CAM system. This case underscores the effectiveness of hybrid ceramic fragments in restoring non-carious cervical lesions, highlighting their long-term stability and clinical success.

• Journal of the Korean Society of Manufacturing Technology Engineers
• /
• v.19 no.6
• /
• pp.739-745
• /
• 2010

The roller gear cam can control the rotational follower periodically by attaching several roller on the circumstance of follower shaft and it is widely used in non-backlash and precise actuating mechanism such as index table or ATC of machine tools. For machining the roller gear cam, 5 axis CNC machine tool is used and the geometric principle of CAM mechanism must be adopted to generate the NC-code and to develop the special CAD/CAM software because there is not commercial CAM system to machine the roller gear cam. The maker of the specially developed software in domestic user is generally from Japan or Taiwan. However these softwares do not reflect the post processing technique for finish machining in the module. Also, there is some limitation for further new application of itself and it needs higher costs for further application. In this study, the CAD/CAM software to overcome these problem was developed. And its reliability was verified by applying it in 5-axis CNC machining. Finally, the experimental result conducted in the 5-axis machining show good consistency in the movement of follower along the flute and in its Size.

• The Journal of Korean Academy of Prosthodontics
• /
• v.61 no.1
• /
• pp.44-54
• /
• 2023

In order to manufacture functional and esthetic prostheses, it is essential to accurately transmit information about the patient's occlusal plane. In particular, in the case of a completely edentulous patient, the occlusal plane is very important to correctly support the soft tissue, to achieve aesthetic harmony with the facial appearance, and to properly pronounce it, and to form a balanced occlusal relationship for stable mastication. In the conventional method, various facebow systems were used to transmit patient's information from the clinic to the laboratory, but there were several limitations in the process of transferring them to CAD. To simplify this process, a prefabricated POP (PNUD Occlusal Plane) Bow system was recently developed. In this case, a CAD-CAM (Computer-aided design-computer-aided manufacturing) treatment dentures reflecting the patient's occlusal plane information was manufactured using the POP Bow system during the treatment of a completely edentulous patient, and aesthetic and functional satisfaction was obtained.