Interdependence Between Tool Misalignment and Cutting Forces in Ultraprecise Single Point Inverted Cutting

Abstract Ultraprecise single point inverted cutting (USPIC) is a microfabrication technique that has been recently developed for the generation of micro-optical microstructures with sharp concave geometries. Among the multiple challenges encountered during the micromachining process, tool alignment represents one of the critical factors affecting the overall accuracy of the microstructure that in turn affects its optical functionality. Since none of the presently available tool alignment techniques was found to perform well in the particular context of the diamond insert used in USPIC, an in-depth analysis of its mechanics was used in this study to provide insight on the interdependence between cutting tool misalignment and cutting forces. For this purpose, an experimental setup was devised to record the 3D cutting forces generated during the fabrication of two representative concave geometries delimited by planar facets. The first test geometry represents an instance of an isolated right triangular prism (RTP) whose quality and optical functionality will be significantly affected by diamond insert misalignment, particularly due to the undesirable contact to occur between the secondary/lateral cutting edges of the tool and the optically nonfunctional RTP facets. By contrast, the second test geometry had both lateral facets removed, such that the cutting conditions obtained in this case could be regarded as similar with that of the classical orthogonal cutting setup. Direct comparisons of the cutting force profiles obtained for the two cutting scenarios enable unequivocal identifications of tool misalignment direction and magnitude, such that targeted corrective actions could be performed to address the issue

Preliminary machine learning analysis and high-speed thermographic visualization of the laser polishing process

11th CIRP Conference on Photonic Technologies [LANE 2020], September 7-10, 202

Effect of initial surface topography during laser polishing process: Statistical analysis

Surface finish is one of the most important quality characteristics of fabricated components. Laser polishing (LP) is one of the advanced manufacturing surface finishing techniques that has been recently developed and successfully employed for improving surface quality without deteriorating the overall structural form through surface smoothing by melting and redistributing a thin layer of molten material. This paper advances the statistical analysis of the LP process emphasizing aspects of the effect of the initial surface topography. Flat and ground initial surfaces are used for comparative statistical analysis of initial and polished profiles obtained experimentally. Their profile geometries and surface quality characteristics, such as, roughness, were compared and analyzed. In addition, LP process was experimentally investigated as a thermodynamic operator represented by a transfer function and it was examined by means of a coherence function

Preliminary experimental analysis of the surface topography formation during laser polishing H13 tooling steel using statistical characteristics of the surface amplitude distribution

48th SME North American Manufacturing Research Conference, NAMRC 48 (Cancelled due to COVID-19

Axial strategy for ultraprecise single point cutting of V-grooves Case 1: constant chip thickness

47th SME North American Manufacturing Research Conference, NAMRC 47, June 10-14, 2019, Pennsylvania, US

Reduction of cutting forces by elliptical vibration in multi-pass ultraprecise single point axial cutting of V-grooves

48th SME North American Manufacturing Research Conference, NAMRC 48 (Cancelled due to COVID-19

Challenges and solutions in laser micro fabrication of micro parts, mechanisms, and sensors

Non-conventional micro fabrication technologies, such as laser micro machining, micro EDM, etc., are [the] most suitable and cost effective choice for prototyping of micro parts/systems, and also in some cases, for batch production. This is especially true for complex microdevices which require functional and/or composite materials other than silicon. In this presentation, NRC-IMTI's capabilities in laser micro fabrication of micro mechanisms, eg., actuators and grippers, integrated with force/displacement capacitive sensors, and in micro fabrication of 2D/3D micro moulds and dies for microfluidics applications are discussed. Systematic representation of the high-precision laser material removal process uncovers main disturbances that affect fabrication with nano/micro-scale accuracy, precision, and geometric quality. Using case studies of micro parts and mechanisms fabricated by the laser micromachining technology, several machining challenges related to non-uniformity and dynamic errors of motions, corner accuracy, asynchronization of motions and laser on/off events in space and time with respect to the part geometry, are evaluated. Also, effect and optimization of several process parameters, such as laser power, focal distance, number of machining passes, etc., are evaluated with respect to the machined surface topology. Results of these studies allowed achieving accuracy and precision of fabricated micro parts and mechanisms within +/- one micrometer or less and surface roughness of 70 nm.Peer reviewed: YesNRC publication: Ye

Improving geometric quality of laser machined parts using high-precision motion system dynamic performance analysis

Dynamic performance of the motion system is a key element for achieving the highest accuracy and precision from a particular laser micromachining system. This paper describes an analysis of the dynamic performance of a high-precision motion system and its relevance to the improvement in geometric quality of the machined parts. The dynamic and statistical parameters of motion are utilized to evaluate the dynamic performance of the entire motion system. Also, experimental results applied to high-laser micromachining allow significant improvements in the precision and quality of the machined parts. An example of a micromachined line pattern on a flexible circuit board is presented. Better geometric quality in machined parts with increased precision in the track width, from +/-2.20 \ub5m up to +/- 0.75 \ub5m was obtained. The results highlight sources of improvement in the part geometric quality and the laser micromachining process.Peer reviewed: YesNRC publication: Ye

An experimental analysis of chip formation in circular micro-end-milling

In conventional circular end-milling practice, chip formation is generally approximated as in linear end-milling. For applications such as micro-milling, circular tool paths are used extensively in the fabrication of high-precision/quality micro features, components, parts, and moulds and dies for biomedica], optoelectronic, and automotive applications. Therefore, more detailed and accurate study of chip formation is required to ensure the highest achievable accuracy, precision and surface quality. In this work, feed per tooth and chip thickness during circular micro end-milling were experimentally studied with the major focus on analysis of the difference in chip formation for tool paths with varying radius. In particular, cutting force signatures were measured synchronously along the tool path radius, especially for lower radii, on chip formation is presented and discussed in detail.Peer reviewed: YesNRC publication: Ye

Electro-thermally driven microgrippers for micro-electro-mechanical systems applications

This paper presents design, fabrication, and performance testing of an innovative, laser machined structure to act as a microgripper. The proposed design constitutes of a pair of identical, cascaded actuation structures oriented in a face-to-face direction, to act as microtweezers. Each microactuator consists of five actuation units joined together horizontally in a consecutive order to build the cascaded structure. The actuation unit incorporates an internal constrainer and two semi-circular-shaped actuation beams. The actuation principle is based on the electro-thermal effect. On application of electrical potential at the backends, the conductive, geometrically complex structure of the microgripper produces non-uniform resistive heating and uneven thermal expansion generating tweezing displacements and force through a cumulative effect of all the individual actuation units within the cascaded microactuators. High-precision laser micromachining process was employed in the fabrication of the copper and nickel-based prototype microgrippers with overall dimension of 1.4\u2009mm(L) 72.8\u2009mm(W) and with relative accuracy within 1%. The geometrical parameters of the prototypes were evaluated in terms of accuracy and precision to demonstrate the fabrication capabilities. Challenges involved and the solutions to develop functional microparts with high aspect ratio (dimensional) with respect to the local elements and overall dimensions were described. The performance of the two microgripper prototypes was analyzed and compared. These microgrippers are useful in micromanipulating and microhandling operations for micro-electro-mechanical systems, biological, medical, chemical, and electro-opto-mechanical engineering applications.JM3 paper No. 04114Peer reviewed: YesNRC publication: Ye