Leopoldo Ruiz-Huerta

Micro-Groove Cutting for Different Materials Using an Elastic Leaf Spring Type Tool Holder

Micro-grooves fabrication is increasing due to its importance in different technology fields, as they are required for higher functional applications such as the development of optical lens or micro channels for heat exchangers. A novel method based on the technology developed for Atomic Force Microscopes (AFM) nano-cutting is proposed, where nano-scratches are made using a micro-cantilever with a sharp tip where a normal load sufficient to remove material is applied. Instead of a rigid system to control the relative position between the tool and the workpiece, AFM nano-cutting uses a force feedback control (FBC) of the normal load on the tool edge in order to maintain a constant cutting depth during the manufacture. Due to the limited scale range of AFM machining, a larger mechanism was developed and consists on a XYZ-stage system where an elastic leaf spring type tool holder is mounted with a diamond tool chip. FBC is not yet implemented on this system; however, basic experiments (micro-grooves cutting) were performed on different materials to verify the feasibility of this setup. With these results, it is possible to analyze the relationship between static indentation tests and the normal load required during the micro-grooves fabrication.

Calibration of ball nose micro end milling operations for sculptured surfaces machining

Ball nose micro end milling can be used for the precise manufacturing of micro cavities for biomedical applications. These cavities are usually machined on hardened steels, which cause rapid cutting tool deterioration and a poor surface quality. The literature presents few works that aid to understand the process behaviour of ball nose micro end milling, in comparison with flat micro end milling. The scarcity in the literature is a consequence of the difficulty of measuring cutting tool deterioration for modelling purposes. In order to contribute to a deeper understanding of the process, this paper presents a strategy for calibrating ball nose micro end milling, featuring additional tool characteristics to gauge deterioration, measured with the aid of focus variation, scanning electron and confocal microscopy. Results show that appropriate evaluation of the process can be made, in terms of finding adequate ranges of feed rates for avoiding undesirable effects as tool wear, ploughing and poor surface quality.

CAD and AM-fabricated moulds for fast cranio-maxillofacial implants manufacture

Purpose – The purpose of this study is to suggest the joint use of computer-aided design (CAD) and additive manufacturing (AM) technology for the fabrication of custom-made moulds, designed for the manufacture of polymethyl methacrylate (PMMA) implants for cranio-maxillofacial reconstruction to reduce their fabrication time. Even though tailor-made skull prostheses with a high technological level and state-of-the-art materials are available in the market, they are not always accessible to the general population in developing countries. Design/methodology/approach – Computed tomography data were handled to create a three-dimensional (3D) model of the injury of the patient, by reconstructing Digital Imaging and Communications in Medicine (DICOM) images into an Standard Tessellation Language (STL) file that was further used to design the corresponding implant using CAD software. Accordingly, a two-piece core and cavity moulds that replicated the implant geometry was also CAD designed. The 3D-CAD data were se...

Micropositioning System for the Study of Neural Activity in Free-Behaving Rats

Neural activity studies in small animals are widely employed in the biomedical research field. These studies are based on the use of micro positioning systems for microelectrodes called micro drives. This article describes the design, development and assessment of a micro drive used for studying neural activity in rats. The proposed micro drive is actuated by a small piezoelectric ultrasonic motor and the motion transmission is achieved by a simple mechanism. The device incorporates a closed-loop position feedback control system to get accurate movements by means of a linear Hall-effect sensor. The proposed system has a stroke of 2064 micrometers and a resolution of 1.3 micrometers, it weighs 2.5 g and it is 10 mm long, 7.6 mm wide and 13 mm high.

Improved Surface-Based Registration of CT and Intraoperative 3D Ultrasound of Bones

The intraoperative registration of preoperative CT volumes is a key process of most computer-assisted orthopedic surgery (CAOS) systems. In this work, is reported a new method for automatic registration of long bones, based on the segmentation of the bone cortical in intraoperative 3D ultrasound images. A bone classifier was developed based on features, obtained from the principal component analysis of the Hessian matrix, of every voxel in an intraoperative ultrasound volume. 3D freehand ultrasound was used for the acquisition of the intraoperative ultrasound volumes. Corresponding bone surface segmentations in ultrasound and preoperative CT imaging were used for the intraoperative registration. Validation on a phantom of the tibia produced encouraging results, with a maximum mean segmentation error of 0.34⁡mm (SD=0.26⁡mm) and a registration accuracy error of 0.64⁡mm (SD=0.49⁡mm).

Design of a 1/4 Wavelength Michelson Interferometer Using a Compact Optical Setup

Interferometry takes advantage of the interference phenomenon of light and it has been used to measure displacement, angles, speed and objects shape for countless applications. Historically, interferometers were developed for optical laboratories with special supports that hold the components, nowadays, commercial systems with high performance and different integration levels are available. This paper presents the design of a Michelson interferometer with a 1/4 wavelength optical resolution and a 1/16 wavelength resolution by means of quadrature signal generation. The proposed interferometer uses a homodyne He-Ne laser. The design considers a compact optical setup, which permits a simple alignment of the system.

The Mexican Contribution to Mechanism and Machine Science and Technology

An overview of current activity related to mechanism and machine research and development in Mexico is presented. Examples of some significant accomplishments are described to illustrate this activity. Historical trends and events that have been influential in promoting work in this area are identified. These include the creation of the National Council for Science and Technology, the implementation of post graduate educational programs, the creation of the Mexican IFToMM Commission, and the establishment of a considerable number of government and private research centers.

Techniques in the Development of Micromachine Tool Prototypes & Their Applications in Microfactories MET Technology

At present, many areas of industry have strong tendencies towards miniaturization of products. Mechanical components of these products as a rule are manufactured using conventional large-scale equipment or micromechanical equipment based on microelectronic technology (MEMS). The first method has some drawbacks because conventional largescale equipment consumes much energy, space and material. The second method seems to be more advanced but has some limitations, for example, two-dimensional (2D) or 2.5-dimensional shapes of components and materials compatible with silicon technology. Here we consider an alternative technology of micromechanical device production. This technology is based on micromachine tools (MMT) and microassembly devices, which can be produced as sequential generations of microequipment. The first generation can be produced by conventional large-scale equipment. The machine tools of this generation can have overall sizes of 100–200 mm. Using microequipment of this generation, second generation microequipment having smaller overall sizes can be produced. This process can be repeated to produce generations of micromachine tools having overall sizes of some millimeters. In this work we analyze the problems of microequipment miniaturization and give some results of first generation microequipment prototyping. Amicromachining center having an overall size of 130 × 160 × 85mm3 was produced and characterized. This center has allowed us to manufacture micromechanical details having sizes from 50 µm to 5 mm. These details have complex three-dimensional shapes (for example, screw, gear, graduated shaft, conic details, etc.), and are made from different materials, such as brass, steel, different plastics etc. Earlier in a Japanese project micromachine tools and micromanipulators were created with expensive elements of precision technology. The high cost of such microequipment slows down its promotion to the market. We propose another method of micromachine tool and micromanipulator creation. We do not use the expensive elements. To obtain the necessary precision we utilize the natural advantages of equipment of small size. The error analysis of the microequipment made in this work shows that the miniaturization of the microequipment automatically leads to decreasing of the errors of the micromachine tools. Examples of the developed microequipment prototypes are given. We have started to investigate and to make prototypes of the assembly microdevices controlled by a computer vision system. In this paper we also describe an example of the applications (microfilters) for the proposed technology.

Scanning laser system to determine the corneal shape

The development and tests of a scanning system to be used to determine the corneal topography with the laser deflectometry method are presented. In this equipment, a He-Ne laser beam scans the cornea by describing a spiral trajectory generated by two components: radial and angular. The first component is produced by the displacement of a plane mirror moved by a linear pneumatic actuator. The second component is produced by passing the beam through a Dove prism which is rotating by means of a belt drive coupled to a high-speed electric motor. Tests were first performed by analyzing both components independently and then they were characterized by combining the two components. Results are discussed and compared to those of an earlier cited work.