Micromilling of thin ribs with high aspect ratios

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.

S. Mekhiel

In metal cutting, the prediction of cutting forces has been the focus of research for very long time. The reason for that is to decrease the cost of performing experimental work whenever the cutting of new material is needed. In recent years a new application for metal cutting was introduced due to the miniaturization of components and the invention of micro electro-mechanical system MEMS. This has led to the introduction of micro machining. Thus the analysis of the cutting system needed revisions. This is because of the domination of other factors during cutting process. Among these factors are the minimum chip thickness and the ploughing forces. In this work the modeling of orthogonal, oblique and milling cutting process in micro scale is presented. The results are verified using published experimental results.

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...

Precision Engineering, 2009

The market for freeform and high quality microdies and moulds made of steel is predicted to experience a phenomenal growth in line with the demand for microsystems. However, micromachining of hardened steel is a challenge due to unpredictable tool life and likely differences in ...

International Journal of Materials Forming and Machining Processes, 2015

Micromachining comprises manufacturing processes that are in the forefront of contemporary industry. The need for high efficiency, high precision, better quality and lower cost makes the study of these processes and the phenomena of the micro regime that accompany, e.g. the size effect, of great importance. The quite popular for modeling manufacturing processes Finite Element Method is applicable in micromachining, too. However, assumptions and simplifications need to be made in order to provide a realistic simulation. In the present paper a numerical simulation using the Third Wave AdvantEdge® software is presented. A FEM model of micromachining of AISI 1045 is used for a parametric analysis of the simulation of micro-cutting. The effect of cutting conditions and tool geometry are investigated and size-effect theories are tested with the aid of the numerical model. From the analysis several useful conclusions are drawn.

Key Engineering Materials, 2014

The on-going trend in product miniaturization, together with the increasing quality and reduction of costs of micro-components, leads to the need of a robust process design, which might additionally avoid the occurrence of defects in the workpiece. Processes like microforming are affected by variations which can be foreseen but not totally mastered in the design stage. One approach is seen in an adaptive control system based on a metamodel processing the data of online measuring. This approach is grounded on in-depth knowledge based on correct and precise process modelling. This paper presents both experimental and simulative study of a microforging process, part of a more complex forming chain. It consists of six parallel ribs on metal strip. The ribs have a width of 250 µm and are spaced by a gap of 150 µm. The process has been studied by different punch forces, analyzing the final geometry of the workpiece. In particular the rib height is considered as critical to quality paramet...

CIRP Annals-Manufacturing Technology, 2011

International Journal of Machine Tools and Manufacture, 2015

This paper compares the size effect behaviour in micro-and macromilling by applying Analysis of Variance on the specific cutting force (k c ) and relating it with the tool edge radius (r e ), workpiece roughness (R a ), cutting force and chip formation when cutting slots in AISI 1045 steel. Size effect is observed in micromilling through hyper-proportional increase of the specific cutting force for feeds per tooth (f) lower than endmill edge radius, reaching levels of grinding process (∼70 GPa) when f≅r e /10. This particular milling condition does not produce chips. The minimum uncut chip thickness (h min ) varied between 22% and 36% of the endmill edge radius. This range was determined by proposing a curve (k c /R a versus f/r e ) where specific cutting force becomes amplified (size effect) due to workpiece roughness association. In addition to the minimum uncut chip thickness, there is a cutting thickness between h min and r e that optimizes workpiece surface integrity and not only

CIRP Annals - Manufacturing Technology, 2006

This paper reviews some of the main drivers, developments and future requirements in the field of micromanufacturing as related to the machining process from the perspective of the recent research and development literature. For the purposes of this paper micromachining includes creation of precise two and three dimensional workpieces with dimensions in the range of a few tens of nanometers to some few millimeters by cutting using defined geometry cutting tools. The review includes topics of process physics, including materials and microstructural effects, machine tools, tooling and sensing, workpiece and design issues, software and simulation tools, and other issues, e.g. surface and edge finish, and outlook for future developments.

Epj Web of Conferences, 2021

Micromachining is an up-to-date technology widely used in different advanced areas like electronics, aerospace and medical industries. For manufacturing components with highest precision and lowest surface roughness, small-sized end mills with working diameter of less than 1 mm are often used. In this paper, in order to determine the functional relationships between structural strength, cutting properties and geometry of small-sized cutting tools, the mathematical models of working part of micro milling cutters were derived.

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.

Journal of Materials Processing Technology, 2010

The paper presents a new approach for predicting micro-milling cutting forces using the finite element method (FEM). The trajectory of the tool and the uncut chip thickness for different micro-milling parameters (cutting tool radius, feed rate, spindle angular velocity and number of flutes) are determined and used for predicting the cutting forces in micro-milling. The run-out effect is also taken into account. An orthogonal FE model is developed. A number of FE analyses (FEA) are performed at different uncut chip thicknesses (0-20 m) and velocities (104.7-4723 mm/s) for AISI 4340 steel. Based on the FE results, the relationship between the cutting forces, uncut chip thickness and cutting velocity has been described by a non-linear equation proposed by the authors. The suggested equation describes the ploughing and shearing dominant cutting forces. The micro-milling cutting forces have been determined by using the predicted forces from the orthogonal cutting FE model and the calculated uncut chip thickness. Different feed rates and spindle angular velocities have been investigated and compared with experimentally obtained results. The predicted and the measured forces are in very good agreement.

Journal of Materials Processing Technology, 2011

This paper presents the prediction of micro-milling forces using cutting force coefficients evaluated from the finite element (FE) simulations. First an FE model of orthogonal micro-cutting with a round cutting edge is developed for Brass 260. The simulated cutting forces are compared against the experimental results obtained from turning tests. The cutting force coefficients are identified from a series of FE simulations at a range of cutting edge radii and chip loads. The identified cutting force coefficients are used to simulate micro-milling forces considering the tool trajectory, run-out and the dynamometer dynamics. The same process is also simulated with a slip-line field based model. FE and slip-line field based simulation results are compared against the experimentally measured turning and micro-milling forces.

Journal of Materials Science &amp; Technology, 2012

He has 25 years of teaching and research experience in manufacturing, materials and mechanical engineering with special emphasis on Machining & Tribology. Currently, he has also interest in sustainable manufacturing and industrial engineering. He is the editor in chief of six international journals, guest editor of journals, books editor, book series editor and scientific advisory for many international journals and conferences. Presently, he is an editorial board member of 20 international journals and acts as a reviewer for more than 70 prestigious ISI Web of Science journals. In addition, he has also published as an author and co-author more than 30 book chapters and 350 articles in journals and conferences (more than 170 articles in ISI Web of Science, h-index 21). The trend towards miniaturization has increased dramatically over the last decade, especially within the fields concerned with bioengineering, microelectronics, and aerospace. Micromilling is among the principal manufacturing processes which have allowed the development of components possessing micrometric dimensions, being used to the manufacture of both forming tools and the final product. The aim of this work is to present the principal aspects related to this technology, with emphasis on the work material requirements, tool materials and geometry, cutting forces and temperature, quality of the finished product, process modelling and monitoring and machine tool requirements. It can be noticed that size effect possesses a relevant role with regard to the selection of both work material (grain size) and tooling (edge radius). Low forces and temperature are recorded during micromilling, however, the specific cutting force may reach high values because of the ploughing effect observed as the uncut chip thickness is reduced. Finally, burr formation is the principal concern with regard to the quality of the finished part.

Production Engineering, 2010

In this paper the influence of a downscaling of the tool diameter and of the machining parameters on the milling process is analyzed. Starting with an analysis of the cutting edge radius of the tools, the influence of the downscaling on the process is determined by analyzing the surface quality and the cutting forces. The simulation system NCChip, which has been developed at the ISF, is used to simulate the cutting forces when using small tool diameters. This simulation is also used to predict the cutting forces for more complex engagement conditions, like increasing radial immersion or milling of a slot pocket. Additionally, the effects of a downscaling on the tool deflection are analyzed, and strategies to reduce these effects are investigated.