Chapter 1: Introduction

Introduction of Laser Machining Processes

1. Motivation of the project “Combined Research and Curriculum Development:

Nontraditional Manufacturing”

Nontraditional manufacturing (NTM) processes refer to processes in which nontraditional

energy transfer mechanism and/or nontraditional media for energy transfer are

involved. The project is focused on nontraditional material removal or machining

processes. They include electrical discharge and electrochemical machining (EDM/ECM),

laser machining processes (LMP),

abrasive waterjet machining (AWJM), among others. NTM processes can machine

precision components from canggih materials. They offer the advantages

of a reduced number of machining steps and a higher product quality. NTM can

also exist within the realm of automated production. Interest in NTM has been

on rise due to increasing interests in the vastly superior properties of innovative

materials such as superalloys, composites and ceramics. NTM offers an attractive

alternative and often the only choice for the processing of these materials.

The new and potential Jasa Machining applications require enhanced process capabilities and

more precise process design and optimization capabilities. In response, substantial

research progress has been made in recent years especially in the areas of process

innovation, modeling, simulation, monitoring and control.

Progress has also been made in education of NTM processes. Education at the introductory level has been appropriate. Innovations and more orchestrated efforts, however, are needed at the upper level undergraduate and introductory graduate (ULUIG) curricula. NTM processes are diverse and of many types. They are also multi-disciplinary, involving thermal, fluids, chemical reaction, material science, Jasa Machining Medan system design and control theory. To teach research level materials at the ULUIG level, more time and effort are needed to prepare students. With more and more new research results being incorporated Jasa Machining Medan into courses with fixed credit hours, teaching efficiency and efficacy need marked improvement. Besides innovations in teaching methodologies, computer aided tools developed in research as well as computer aided teaching technologies offer great opportunities in this endeavor.

The objectives of this project, therefore, are:

To develop methodologies and educational materials to incorporate recent research results in NTM processes and systems into ULUIG level curricula

To prepare a new generation of engineers who have the analytic background knowledge and process design/optimization skills by using modern tools

To establish a national model of effective and efficient learning of multi-disciplinary subjects.

Laser Machining Process (LMP) is one of seven modules of this project.

2. Preview of Laser Machining Process (LMP)

Laser

machining is the material removal process accomplished through

laser and target material interactions. Generally speaking, these processes

include laser drilling, laser cutting, and laser grooving, marking or scribing.

Laser machining processes transport photon energy into the sasaran material in the form of thermal energy or photochemical energy, they remove material by melting and blow away, or by direct vaporization/ablation.On the other hand, traditional machining processes rely on mechanical stresses induced by tools to break the bonds of materials. This basic difference in material removal mechanism decides the advantages and disadvantages of LMP compared with traditional machining processes.

Laser machining is localized, non-contact machining and is almost reacting-force free, while traditional machining usually has direct mechanical contact and need devices to balance the machining force, work piece needs clamping. The forces in laser machining are of micro scale. The photon pressure on sasaran material is negligible for bulk material. This offers LMP flexibility in machining delicate parts where no large mechanical force can be acted on. Another big advantage is that fixtures can be greatly simplified compared with traditional machining.

LMP can remove material in very small amount, while traditional machining remove material in macro scale. LMP are said to remove material “Atom by Atom”. For this reason, the kerf in laser cutting is usually very narrow, the depth of laser drilling can be controlled to less than one micron per laser pulse and shallow permanent marks can be made with great flexibility. In this way material can be saved, which may be important for precious materials or for delicate structures in micro-fabrications. But this also means small removal rate in LMP compared with traditional machining. Laser machining is not good at bulk material removal through pure thermal effects.The ability of accurate control of material removal makes laser machining an important process in microfabrication and micro-electronics. Also laser cutting of sheet material with thickness less than 20mm can be fast, flexible and of high quality, and large holes or any complex contours can be efficiently made through trepanning.

Heat Affected Zone(HAZ) in laser machining is relatively narrow and the re-solidified layer is of micron dimensions. For this reason, the distortion in laser machining is negligible. In traditional machining, large areas of work hardening is almost unavoidable.

LMP can be applied to any material that can properly absorb the laser irradiation, while traditional machining processes have to choose suitable tools for materials with different hardness or abrasiveness. It is difficult to machine hard materials or brittle materials such as ceramics using traditional methods, laser is a good choice for solving such difficulties.

LMP can achieve final quality level machining results in one process, while in traditional machining several processes are commonly used. Laser cutting edges can be made smooth and clean, no further treatment is necessary. High aspect ratio holes with diameters impossible for other methods can be drilled using lasers. Dross adhesion and edge burr can be avoided, geometry precision can be accurately controlled. The machining quality is in constant progress with the rapid progress in laser technology. Although some traditional machining can achieve higher surface qualities than common LMP, LMP has the potential of nm scale machining. It was reported that laser was used for interactive optics finishing.

Small blind holes, grooves, surface texturing and marking can be achieved with high quality using LMP. Traditional machining may be advantageous for macro scale applications, it is usually more economical and efficient to use LMP for micro scale applications.

LMP has the potential for more flexibility. Laser light can be transmitted and reflected to the desired locations at high speeds, precise 3D positioning can be conveniently realized. The combination of fiber transmitted laser energy and robots technology can provide a system with great dimensional freedom.

Laser machining is sensitive to the focusing property of the laser beam. At

the focus the laser intensity is highest, away from it laser intensity drops.

The Depth of Focus of the laser beam

is relatively small (tens of microns to around a hundred millimeters) , the

cutting depth is thus limited due to this factor along with other complexities

when the cutting depth increases.

Laser technology is in rapid progressing, so do laser machining processes.High power lasers suitable for laser machining are becoming more and more compact, some systems can generate lasers with tunable wavelengths and pulse duration.A quiet, compact but very powerful laser machining system will be used more and more widely!

In summary, laser machining processes are non-contact, flexible and accurate machining processes applicable to a wide range of materials.And they are in rapid developing. In fact laser machining is only a small fraction of laser related applications and all these areas are in rapid development. In this module we will discuss laser machining related topics.

tiga. Methodology behind this project

Energy, Material, System and Information

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