**Precision Machining**

Editor

**Angelos P. Markopoulos**

MDPI • Basel • Beijing • Wuhan • Barcelona • Belgrade • Manchester • Tokyo • Cluj • Tianjin

*Editor* Angelos P. Markopoulos School of Mechanical Engineering National Technical University of Athens Athens Greece

*Editorial Office* MDPI St. Alban-Anlage 66 4052 Basel, Switzerland

This is a reprint of articles from the Special Issue published online in the open access journal *Machines* (ISSN 2075-1702) (available at: www.mdpi.com/journal/machines/special issues/ precision machining).

For citation purposes, cite each article independently as indicated on the article page online and as indicated below:

LastName, A.A.; LastName, B.B.; LastName, C.C. Article Title. *Journal Name* **Year**, *Volume Number*, Page Range.

**ISBN 978-3-0365-2837-3 (Hbk) ISBN 978-3-0365-2836-6 (PDF)**

© 2022 by the authors. Articles in this book are Open Access and distributed under the Creative Commons Attribution (CC BY) license, which allows users to download, copy and build upon published articles, as long as the author and publisher are properly credited, which ensures maximum dissemination and a wider impact of our publications.

The book as a whole is distributed by MDPI under the terms and conditions of the Creative Commons license CC BY-NC-ND.

## **Contents**


## **Dario Croccolo, Omar Cavalli, Massimiliano De Agostinis, Stefano Fini, Giorgio Olmi, Francesco Robusto and Nicol `o Vincenzi** A Methodology for the Lightweight Design of Modern Transfer Machine Tools

Reprinted from: *Machines* **2018**, *6*, 2, doi:10.3390/machines6010002 . . . . . . . . . . . . . . . . . **109**

## **About the Editor**

### **Angelos P. Markopoulos**

Angelos P. Markopoulos is an Associate Professor at the School of Mechanical Engineering, National Technical University of Athens, Greece. His research includes topics such as precision and ultraprecision conventional and non-conventional machining processes with a special interest in advanced manufacturing and Industry 4.0. Furthermore, he is an expert in manufacturing technology modeling and simulation, including the finite element method, artificial intelligence, and molecular dynamics. He is the author of more than 140 papers in journals, conferences, and book chapters on the above-mentioned areas and a member of the editorial boards of several international journals.

## **Preface to "Precision Machining"**

Material removal processes, conventional and non-conventional ones, are considered exceptionally important manufacturing methods that are used for the production of mechanical components. A key feature of these processes is their ability to produce final products with high accuracy and of high quality. Conventional and non-conventional machining, as well as abrasive processes, are vital for the production of high-quality components from many different materials categories. Automotive, aerospace and medical industries are only some of the sectors that machined components of high dimensional accuracy, exceptional properties, complex sizes and usually from difficult-to-machine materials, are employed. The research in the refinement of machining or the introduction of new features is ongoing and fast-growing. Precision machining on large scale components but in the micro- and nano-regime as well, concentrate the interest of the researchers. In the success of the research there are other aspects that need to be considered as the machine tools design and control, cutting tools, metrology and quality control, manufacturing systems and automation and of course modeling and simulation with various methods such as finite elements method, molecular dynamics and soft computing.

This book aims at presenting recent advances and technologies in the aforementioned fields and indicate the future trends for precision machining. More specifically, a work on laser machining that allows the machining of complex geometries with high precision surface quality and productivity in a wide range of materials is presented in [1]. A method is proposed that helps the machine operator to select the optimal process parameters. An extensive experimental work is carried out, where the average output power, the repetition rate and the scanning speed of laser engraving on a steel plate at various combinations are studied and the effectiveness of the process through the removed material layer thickness and the material removal rate is assessed. In the next study [2], the experimental analysis of profile end-milling and more specifically the effect of cutter runout on cutter vibration and, by extension, on how this affects the chip removal and, thereby, the workpiece topomorphy, is presented. Various cutting conditions such as the cutting speed, feed rate, and the axial depth of cut are considered and the effect of cutter runout is evaluated. The third work [3], is dedicated to experimental studies on drilling with solid carbide tools workpieces of Al7075. The effect of cutting speed, feed rate, diameter of the tool on the thrust force (Fz) and the cutting torque (Mz) are evaluated and analyzed through response surface methodology (RSM) and analysis of variance (ANOVA). The diameter of cut and the feed rate were found to be the factors of high significance, while cutting speed did not considerably affect the Fz and Mz in the experiments that were performed. In the next interesting work [4], a knurled interference fit, i.e., a machine part connection made by a plastic joining, is examined. The combination of the friction and form fit, which are responsible for torque transmission, results in a higher power density than conventional connections. Experimental investigations on the shaft chamfer angle (100Cr6) and hub-diameter-ratio (AlSi1MgMn) are performed and analytical approaches are developed for calculating the joining force and maximal torque capacity. The presented calculation approach is an accurate tool for the assessment of machine designs of the knurled interference fit and helps to save from time-extensive tests. The work of Zhang et al. [5] pertains to annular polishing technology, which is an important optical machining method for achieving a high-precision mirror surface on silicon carbide and aims on avoiding the over-polishing of the specimen edge and thus prevent the deterioration of the surface quality. At first an analytical investigation of the the kinematic coupling of multiple relative motions in the annular polishing process is considered. Subsequently, an analytical model that addresses the principle of material removal at specimen edge based on the Preston equation and the rigid body contact model is derived. Then finite element simulations and experiments, involving annular polishing of silicon carbide (SiC), are performed, which jointly exhibit agreement with the derived analytical material removal model.

Felho and Kundr ˝ ak [6] study the effect of increasing feed per tooth on the topography of ´ the surface in fly-cutting and in multi-point face milling. The study takes into account the axial run-out of the inserts. Theoretical roughness values were modelled, the real values were tested in experiments and in both cases the impact of the run-out of the cutting edges and the change of the chip cross-section were also taken into account. Based on the performed experiments it can be stated that the accuracy of the introduced roughness prediction method increases with the increase in feed, and therefore the application of the method in the case of high-feed milling is particularly effective. The next work [7] is an in-depth analysis of cutting procedure, which is a topic of particular interest in manufacturing efficiency; in large-scale production, the effective use of production capacities and the revenue-increasing capacity of production are key conditions of competitiveness. That is why the analysis of time and material removal rate, which are in close relation to production, are important in planning a machining procedure. Thus, three procedures applied in hard cutting are compared on the basis of these parameters and a new parameter, the practical parameter of material removal rate, is introduced. The results can give some useful indications about machining procedure selection. The following study [8] is focused on the design and manufacturing of medical implants. The methodology of designing and machining the femoral component of total knee replacement using a 3-axis Computer Numerical Control (CNC) machine is presented, and then, the results of the machining process, as well as the evaluation of implant surface quality, are discussed in detail. Analysis of the results indicated the appropriate process conditions for each part of the implant surface and led to the determination of optimum machining strategy for the finishing stage.

The double row tapered roller bearings and the manufacturing methods for producing the windows found in bearing cages are the subject of [9]. On the dimensional precision of windows, the clearance between punches and die, the work stroke length and the workpiece thickness could are crucial factors. To evaluate their influence, experimental research was undertaken, considering the height and the length of the cage window and the distance between the contact elements of the cage. The next study [10] deals with the numerical and experimental characterization of the structural behavior of a railroad switch machine. The results have been validated by means of an ad-hoc designed experimental apparatus. The last work [11] deals with a modern design approach via finite elements in the definition of the main structural elements (rotary table and working unit) of an innovative family of transfer machine tools. Using the concepts of green design and manufacture, as well as sustainable development thinking, the advantages derived from their application in this specific field is highlighted. The design is conceived in a modular way, so that the final solution can cover transfers from 4 to 15 working stations. The loading input forces for the analyses have been evaluated experimentally via drilling operations carried out on a three-axis CNC unit. The definition of the design force made it possible to accurately assess both the rotary table and the working units installed in the machine.

The guest editor would like to thank the authors for their valuable high-quality work submitted, the reviewers for their efforts and time spent in order to improve the submissions, and the publisher for their excellent work and cooperation.

#### **References**

1. Nikolidakis, E.; Choreftakis, I.; Antoniadis, A. Experimental Investigation of Stainless Steel SAE304 Laser Engraving Cut-ting Conditions. Machines 2018, 6, 40.

2. David, C.; Sagris, D.; Stergianni, E.; Tsiafis, C.; Tsiafis, I. Experimental Analysis of the Effect of Vibration Phenomena on Workpiece Topomorphy Due to Cutter Runout in End-Milling Process. Machines 2018, 6, 27.

3. Kyratsis, P.; Markopoulos, A.P.; Efkolidis, N.; Maliagkas, V.; Kakoulis, K. Prediction of Thrust Force and Cutting Torque in Drilling Based on the Response Surface Methodology. Machines 2018, 6, 24.

4. Suchy, L.; Leidich, E.; Gerstmann, T.; Awiszus, B. Influence of Hub Parameters on Joining ´ Forces and Torque Transmission Output of Plastically-Joined Shaft-Hub-Connections with a Knurled Contact Surface. Machines 2018, 6, 16.

5. Zhang, J.; Han, L.; Liu, H.; Shi, Y.; Yan, Y.; Sun, T. Theoretical and Experimental Studies of Over-Polishing of Silicon Carbide in Annular Polishing. Machines 2018, 6, 15.

6. Felho, C.; Kundr ˝ ak, J. Effects of Setting Errors (Insert Run-Outs) on Surface Roughness in Face ´ Milling When Using Circular Inserts. Machines 2018, 6, 14.

7. Kundrak, J.; Molnar, V.; Deszpoth, I. Comparative Analysis of Machining Procedures. Machines 2018, 6, 13. 8. Markopoulos, A.P.; Galanis, N.I.; Karkalos, N.E.; Manolakos, D.E. Precision CNC Machining of Femoral Component of Knee Implant: A Case Study. Machines 2018, 6, 10.

9. Rˆıpanu, M.; Nagˆıt¸, G.; Slatineanu, L.; Dodun, O. The Dimensional Precision of Forming ˘ Windows in Bearing Cages. Machines 2018, 6, 9.

10. Croccolo, D.; De Agostinis, M.; Fini, S.; Olmi, G.; Robusto, F. Numerical and Experimental Characterization of a Railroad Switch Machine. Machines 2018, 6, 6.

11. Croccolo, D.; Cavalli, O.; De Agostinis, M.; Fini, S.; Olmi, G.; Robusto, F.; Vincenzi, N. A Methodology for the Lightweight Design of Modern Transfer Machine Tools. Machines 2018, 6, 2.

> **Angelos P. Markopoulos** *Editor*

*Article*
