Micronization of a Soft Material: Air-Jet and Micro-Ball Milling

Powder Technology, 2004

Milling and micronization of whey protein concentrate (WPC) and zeolite (type clinoptilolite) were carried out. In this work, samples were treated using laboratory equipment for tribomechanical micronization (TMA equipment) at three different rotor speeds. Before and after the tribomechanical treatment, analysis of the particle size and particle size distribution, as well as the specific area, was carried out, in addition to scanning microscopy.

2011

Drug powders containing micron-size drug particles are used in several pharmaceutical dosage forms. Many drugs, especially newly developed substances, are poorly water soluble, which limits their oral bioavailability. The dissolution rate can be enhanced by using micronized drugs. Small drug particles are also required in administration forms, which require the drug in micron-size size due to geometric reasons in the organ to be targeted (e.g., drugs for pulmonary use). The common technique for the preparation of micron-size drugs is the mechanical commination (e.g., by crushing, grinding, and milling) of previously formed larger particles. In spite of the widespread use of this technique, the milling process does not represent the ideal way for the production of small particles because drug substance properties and surface properties are altered in a mainly uncontrolled manner. Thus, techniques that prepare the drug directly in the required particle size are of interest. Because ph...

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...

Interdisciplinary Description of Complex Systems Scientific Journal, 2014

Trend of miniaturization of products and consequently its components nowadays can be evident in almost every production field. To accomplish requirements imposed by miniaturization micromachining proved to be a satisfied manufacturing technique. Herein the term micromachining refers to mechanical micro cutting techniques where material is removed by geometrically determined cutting edges. The aim of this review article is to summarize existing knowledge and highlight current challenges, restrictions and advantages in the field of micromachining.

Journal of Materials Science & 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.

Powder Technology, 1999

Many studies have been conducted to help understand the effects of the variables involved in jet milling. The first part of this work is an attempt to summarise the results published in the literature concerning horizontal and vertical jet mills. This focuses on the research of the optimal design of the mills and on the improvement of their performance. Several publications have been found, concerning mineral grinding. It seemed more interesting to present results on organic crystals' jet milling in the second part of this paper. The experiments concern three organic substances, and were run on three different spiral jet mills: Chrispro-Jetmill 50 and 100 and MicronMills 8 Y. The results are presented in terms of specific energy consumption with an adaptation of the correlation proposed by Sarma. These representations show that, within the operating energy range and above a critical energy value, the creation of specific surface area corresponds to an increase of fine particles production.

2013

Micro-mechanical machining using diamond tools is advantageous to other micromanufacturing techniques as it can create complicated geometric features with high precision, and it is applicable to a wide range of materials including polymers and metals. The effectiveness of manufacturing micro-scale features can be enhanced by understanding the process and interactions between the tools and materials.

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...