Micromilling strategies for machining thin features

Micro-milling of metal structures with "thin" features represents a major challenge towards broadening the use of this technology in a range of micro-engineering applications, for example in producing multi-channel micro-structures, housings for mechanical micro-devices and surgical instruments. The most common thin features seen in micro- engineering products are ribs and webs. This research identifies the main factors affecting the reliability of micro-milling technology when employed for the machining of micro-components incorporating thin features. The general principles that should be followed in designing machining strategies for such features are discussed in the paper. Taking these general principles into account, new strategies are proposed to reduce the negative effects of identified factors on part quality and at the same time to overcome some of the problems associated with the use of conventional machining strategies for micro- milling of ribs and webs. To imp...

Micro-milling is one of the technologies widely used to manufacture microstructures and tooling inserts for micro-injection moulding and hot embossing. A number of manufacturing constraints remain that limit the application of this technology. One of these constraints is that the existing machining strategies are not appropriate for the manufacture of features that are common in micro parts. This paper discusses an approach for optimising these strategies. The aim is to provide users of CAM systems with tools enabling them to generate cutter paths that take into account the specific conditions arising during micro-milling. The paper studies the advantages and disadvantages of using different machining strategies for micro-milling and then verifies their capabilities experimentally. Also, an approach is proposed for storing and re-using expert knowledge about micro machining strategies associated with different feature types.

4M 2006 - Second International Conference on Multi-Material Micro Manufacture, 2006

Abstract Micro-milling is one of the technologies that is currently widely used for the production of micro-components and tooling inserts. To improve the quality and surface finish of machined microstructures the factors affecting the process dynamic stability should be studied systematically. This paper investigates the machining response of a metallurgically and mechanically modified material. The results of micro-milling workpieces of an Al 5000 series alloy with different grain microstructure are reported. In particular, the machining response of three Al 5083 workpieces whose microstructure was modified through a severe plastic deformation was studied when milling thin features in microcomponents. The effects of the material microstructure on the resulting part quality and surface integrity are discussed and conclusions made about its importance in micro-milling. The investigation has shown that through a refinement of material microstructure it is possible to improve significantly the surface integrity of the micro-components and tooling cavities produced by micro-milling.

Proceedings on Engineering Sciences

Development of micro-devices parts is intensified with developments in medical device and energetic industry. In production of micro-parts (micro-pump, micro-gears, micro-manipulators, etc.), a wide range of engineering materials is encountered. Strict requirements are set in terms of characteristic of micro-parts machined surfaces, such are low surface roughness, advanced tribological characteristic, etc. In this paper is analysed possibilities of different metallic materials mechanical micro-machining. The analysis includes the analysis of the generating and characteristics of the machined surfaces, and influence of a whole set of parameters on surface characteristic. The results showed the benefits of mechanical micromachining and proved that it can achieve satisfactory results of the surface characteristics indicators.

Advances in Manufacturing, 2020

Micro-milling is a precision manufacturing process with broad applications across the biomedical, electronics, aerospace, and aeronautical industries owing to its versatility, capability, economy, and efficiency in a wide range of materials. In particular, the micro-milling process is highly suitable for very precise and accurate machining of mold prototypes with high aspect ratios in the microdomain, as well as for rapid micro-texturing and micro-patterning, which will have great importance in the near future in bio-implant manufacturing. This is particularly true for machining of typical difficult-to-machine materials commonly found in both the mold and orthopedic implant industries. However, inherent physical process constraints of machining arise as macro-milling is scaled down to the microdomain. This leads to some physical phenomena during micro-milling such as chip formation, size effect, and process instabilities. These dynamic physical process phenomena are introduced and d...

MATEC Web of Conferences, 2018

With the trend towards miniaturization, micromachining become more and more important in fabricating micro parts. The micromachining process that involved in this study is micro milling. The focus of the study is on the comparison performance between various numbers of flutes (4-flutes, 6-flutes and 8-flutes) with various helix angle (25º,30º and 35º) in micro end milling tool geometry with the conventional micro end milling, 2-flutes micro end milling. Cemented carbide is the material that been used for this study. The main problem about the two flutes micro end milling is it easily wears in a short time. In this study, finite element analysis of the model using cantilever beam principle theory. The tools will be modelled and simulate using Abaqus/CAE 6.10. The tool performance of the designed tool will be evaluated by using the maximum principal stress, σ_max. According to the analysis, weakest geometry is 2-flutes micro end milling and the strongest is 8-flutes micro end milling. 8-flutes micro end milling can be the option to replace the conventional micro end milling.

International Journal of Engineering Research & Technology (IJERT) IJERT , 2015

Micromachining is the most basic technology for the production of miniaturized parts and components. It includes bulk micromachining processes which produce structures inside a substrate and surface micromachining processes which are based on the deposition and etching of different structural layers on top of the substrate. On the other hand, in "mechanical/conventional" micromachining the material removal process resembles macroscopic machining processes such as drilling, milling and others. From such a point of view, micromachining encompasses microelectromechanical systems (MEMS), microsystems technologies (MST) and, in addition, includes processes related to the production and packaging of microsystems [MAS 00a]. Micromachining by precision technology such as 3D microEDM, microlaser machining, microcutting, microgrinding, etc. can produce microscopic and mesoscopic mechanical structures of complex shapes.

Research in this report is preliminary experimental research on high performance milling and micro-milling of hard-to-machining materials (tool steels), constructive materials (aluminum) and materials for EDM electrodes (copper). The main idea of future research is possibility of micro-milling of hard-to-machine materials on precision high-speed milling machines. It will be done in order to avoid of non-conventional machining processes, which are dominantly used for micro-structures in practice today. In some cases, using of non-conventional processes (EDM, LBM, etc.) for micro-structures require large investments in machine systems.

2014

The miniaturization of devices has been under high demand since they offer added benefits such as high mobility and portability, better accessibility and functionality, and lower energy consumption. Specific applications include energy devices such as heat sinks and exchangers, biomedical devices such as microfluidic devices, microneedles, and implants, automotive and aircraft components, and sensory devices. As the demand to produce such miniature products continue to increase, an imminent need for advanced manufacturing processes that can fabricate very small parts directly, cost effectively, and with high productivity arises. Micro-end milling is one of the most promising manufacturing processes capable of fabricating discrete parts with complex features in micro-scale (feature size < 1000 µm) due to its high flexibility for processing a wide range of materials with a low setup cost. However, micro-end milling process possesses several difficulties in precision fabrication of such products due to size effect, rapid tool wear, burr formation, tool and workpiece deflection, and premature tool breakage. In addition, these micro-products require tighter geometrical tolerances and iii better surface quality. These difficulties and requirements make the selection of process parameters for high performance micro-end milling very challenging. In this research, we conducted experimental and numerical modeling studies and multi-objective process optimization for micro-end milling. An extensive study of process parameters such as tool coatings, cutting velocity, feed rate, and axial depth of cut was performed in order to understand the effects of these parameters on the performance of micro-end milling process. Novel finite element based process models in 2-D and 3-D have been developed. Both experimental models and finite element based process simulations were utilized to construct various predictive models for the process outputs. These predictive models include physics-based outputs such as chip deformations, tool forces and temperatures, tool wear rate and depth, as well as performance related measures such as surface finish, burr formation, and tool life. Furthermore, we developed a comprehensive decision support system by using the predictive models which can facilitate a selection of process parameters and toolpath strategies based on desired performances. Multi-objective optimization studies were conducted by utilizing predictive models for obtaining optimal decision variable sets. Moreover, this research also demonstrates the current capabilities of micro-end milling in fabricating micro-products such as heat sinks in brass and implants in titanium alloys, and micro-needles in polymers.

Open Chemistry, 2022

In this study, the effect of cutting conditions on surface integrity was investigated in micromilling of magnesium alloy (AZ91). Microtool diameter, cutting speed, feed rate, and depth of cut parameters are used. These variables were investigated at three different levels with the Taguchi L 9 experimental design method. The leastbest objective function was used. As a result of the experiments, surface roughness values were obtained. It has been determined that surface roughness values and depth of cut are effective parameters. After evaluating the results obtained, variance and regression analyses were performed. Based on the analysis of variance, 58.73% feed rate was found for the 1.0 mm diameter tool, on the other hand, for the 0.8 mm diameter tool, the depth of cut was found to be an effective parameter with 53.6%.