Wood Machining E-Book

• Herausgeber: John Wiley & Sons
• Kategorie: Fachliteratur
• Sprache: Englisch

Seitenzahl: 279

Veröffentlichungsjahr: 2013

Beschreibung

Wood as an engineering material can be technically defined "as a hygroscopic, orthotropic, biological, and permeable material having extreme chemical diversity and physical complexity with structures, that vary extensively in their shape, size, properties and function". Therefore, using wood to its best advantage and most efficiency in engineering applications, specific characteristics or chemical, physical and mechanical properties must be considered. The products are divided into two classes, solid wood and composite wood products. Solid wood includes shipbuilding, bridges, flooring, mine timbers, etc. Composite wood products include insulation board, plywood, oriented strand board, hardboard and particle board. In recent years, the machining of wood products has acquired great importance due the short supply of wood and increasing environmental awareness among users and manufacturers. The optimization of the machining process centers around the mechanism of chip formation, tool wear, workpiece surface quality, crack initiation and propagation of different types of wood. Other factors are also humidity, temperature, static preloads, and vibrations that can affect the wood during the machining process. The book provides some fundamentals and recent research advances on machining wood and wood products.

Leseprobe

Table of Contents

Preface

Chapter 1. Machining of Wood and Wood Composites

1.1. Introduction

1.2. Wood and wood-based composites

1.3. Approach to cutting

1.4. Main techniques of machining

1.5. Problems of machining wood and wood composites – a review

1.6. Into the future – further scenarios of wood and wood composites machining

1.7. Acknowledgement

1.8. Bibliography

Chapter 2. Wood and Wood-based Panel Machining Quality

2.1. Solid wood machining

2.2. Wood-based panel machining

2.3. Surface quality

2.4. Case study: solid wood machining and surface quality evaluation

2.5. Case study: particleboard machining and edge quality evaluation

2.6. Bibliography

Chapter 3. Reducing Tool Wear by Cryogenic Treatment and Cooling with Refrigerated Air when Processing Medium Density Fiberboard

3.1. Introduction

3.2. Effects of refrigerated air

3.3. Effects of cryogenic treatment and refrigerated air

3.4. Acknowledgements

3.5. Bibliography

Chapter 4. Wearing Mechanisms Contributing to Reduced Tool Life after Wood and Secondary Wood Products Machining

4.1. Introduction

4.2. Cutting edge-material cut interface

4.3. TGA indirect evidence of HTTR

4.4. Theoretical QC analysis of HTTR

4.5. Investigations of direct evidence of HTTR

4.6. Cutting edge SEM image examinations

4.7. Synergistic effect of high temperature reactions and mechanical wear

4.8. Final remarks

4.9. Conclusions

4.10. Acknowledgements

4.11. Bibliography

Chapter 5. Monitoring Surface Quality on Molding and Sawing Processes for Solid Wood and Wood Panels

5.1. Introduction

5.2. General concepts

5.3. Monitoring the cutting process

5.4. Surface roughness and quality for solid wood and panels

5.5. Concluding remarks

5.6. Acknowledgements

5.7. Bibliography

Chapter 6. Evaluating the Roughness of Sanded Wood Surfaces

6.1. Introduction

6.2. Profile filtering applied to wood surfaces

6.3. A proposed method for separating processing roughness from anatomical roughness

6.4. A case study: the processing roughness of oak surfaces sanded with various grit sizes

6.5. Concluding remarks

6.6. Perspectives

6.7. Acknowledgements

6.8. Bibliography

List of Authors

Index

First published 2011 in Great Britain and the United States by ISTE Ltd and John Wiley & Sons, Inc.

Apart from any fair dealing for the purposes of research or private study, or criticism or review, as permitted under the Copyright, Designs and Patents Act 1988, this publication may only be reproduced, stored or transmitted, in any form or by any means, with the prior permission in writing of the publishers, or in the case of reprographic reproduction in accordance with the terms and licenses issued by the CLA. Enquiries concerning reproduction outside these terms should be sent to the publishers at the undermentioned address:

ISTE Ltd 27–37 St George's Road London SW19 4EU UKwww.iste.co.uk

John Wiley & Sons, Inc. 111 River Street Hoboken, NJ 07030 USA www.wiley.com

© ISTE Ltd 2011

The rights of J. Paulo Davim to be identified as the author of this work have been asserted by him in accordance with the Copyright, Designs and Patents Act 1988.

Library of Congress Cataloging-in-Publication Data

Wood machining / edited by J. Paulo Davim. p. cm. Includes bibliographical references and index. ISBN 978–1-84821-315-9 1. Millwork (Woodwork) 2. Woodworking machinery. I. Davim, J. Paulo. TS878.W66 2011 674--dc23 2011014037

British Library Cataloguing-in-Publication Data A CIP record for this book is available from the British Library ISBN 978–1-84821-315-9

Preface

In general, wood as an engineering material can be technically defined “as a hygroscopic, orthotropic, biological, and permeable material having extreme chemical diversity and physical complexity, with structures that vary extensively in their shape, size, properties and function”. Therefore, using wood to its best advantage and most efficiency in engineering applications, specific characteristics or chemical, physical and mechanical properties must be considered. It is usual to divide the products into two classes, solid wood and composite wood products. Solid wood includes, for example, applications in furniture and cabinets, shipbuilding, bridges, flooring, mine timbers and posts. Composite wood products include, for example, insulation board, plywood, oriented strand board, hard-board and particle board.

In recent years the machining of wood products has acquired great importance due to the short supply of wood and increasing environmental awareness among users and manufacturers. The optimization of the machining process is around the chip formation, tool wear, workpiece surface quality, crack initiation and propagation of different types of wood. Other factors are also taken into consideration such as humidity, temperature, static preloads, and vibrations that can affect the wood during the machining process.

The purpose of this book is to present a collection of examples illustrating the state of the art and research developments in the machining of wood and wood products. Chapter 1 presents the fundamentals of machining of wood and wood composites. Chapter 2 covers wood and wood-based panels’ machining quality. Chapter 3 contains information on reducing tool wear by cryogenic treatment and cooling with refrigerated air when processing medium density fiberboard. Chapter 4 is dedicated to wearing mechanisms contributing to tool life decrease by machining wood and secondary wood products. Chapter 5 covers monitoring surface quality on molding and sawing processes for solid wood and wood panels. Finally, in Chapter 6, evaluating the roughness of sanded wood surfaces is presented.

This book can be used as a research book for a final undergraduate engineering course (for example, wood, mechanical, materials, manufacturing, etc.) or as a subject on machining of wood and wood products at the postgraduate level. This book can also serve as a useful reference for academics, wood researchers, mechanical, manufacturing and materials engineers, professionals in areas related to the manufacturing of wood and wood products. The interest of this book is evident for many important research centers, laboratories and universities throughout the world. Therefore, it is hoped that this book will encourage and enthuse other research in this important field of engineering and technology.

I would like to extend my gratitude to ISTE-Wiley for this opportunity and for their professional support. Finally, I would like to thank all the chapter authors for their availability to work on this project.

J. Paulo DAVIM

University of AveiroPortugalMay 2011

Chapter 1 Machining of Wood and Wood Composites1

1.1. Introduction

While machining of wood has been conducted for many centuries, and significant progress has been made in the cutting of wood, the shape of the tool – wedge – has not changed. With the progress of the new tool materials, more abrasion resistant and durable blades are being introduced to machining.

The rapid development of composite wood products also causes the improvement of the techniques and machines used to process such materials. New theories regarding cutting help with better utilization of raw materials. Computerized control of the machines makes it easier to achieve the assumed quality and productivity.

1.2. Wood and wood-based composites

Although wood is well known to all of us, a compact characterization of this material can be useful before starting the analysis of wood machining aspects. Chemical composition of wood, depends, among other things, on its species, it is based on cellulose (about 4555%), lignin (about 2530%), hemicelluloses (1020%), resins, rubbers (4.59.5%) and mineral contamination (about 0.5%). Because of the significantly higher share of cellulose and lignin only those two components are described below.

Cellulose, polysaccharide with a crystalline structure, is the main component of the cell wall structure. The molecules of cellulose are bonded together in long chains creating elongated fibers – micelles. In the free spaces between the bunches of micelles the lignin and water are stored. Cellulose is not water and alcohol soluble, and can be extracted from the cell wall only in an acid environment.

Lignin is an amorphous material, which fills the frame of the cell wall, and is fixed with cellulose mechanically and chemically. The presence of lignin makes the cell walls harder and stiffer.