Advanced Manufacturing Processes (MECH60132):

1. Aims and Objectives

This laboratory exercise aims to further enhance the understanding of basic characteristics of precision laser processing through the blended learning of the use of different laser systems. The procedure involves the processing of standard laboratory materials such as, stainless steel and polymers. The overall aim of the project is to make each undergraduate student their own keying, made using the laser systems in the laboratory.

· To introduce the operating procedures of complex laser systems and demonstrate their use in advance production. 

· To understand the effects of operating parameters and material used on the process result. 

· To familiarise the use of analytical equipment such as optical microscope for the examination of processed samples. 

· To understand the basic safety issues involved in laser processing. 

2. Exercises 

Laser cutting, marking and Micromachining will be demonstrated. In all cases, the following basic steps are undertaken:

· Brief introduction to the layout of the laser system.

· Experimental Preparation, which involves the startup of the laser systems, the alignment of the processing table and the scanning equipment, the preparation of work pieces, safety systems, etc. The procedures should be noted.

· Examination of Samples: This involves the use of optical microscope. Surface patterns, damage analysis, as well as size comparisons will be undertaken.  

· Calculation of beam sizes, fluencies, and other measurement parameters.

2.1. System A – Cutting Exercise

The machine used is an HPC fibre laser cutting system, which is coupled to a 3-axis CNC stage. The following will be demonstrated and performed in the exercise: 

· Alignment Process: Setting up of a sample in the process region. 

· Cutting Exercise: Setting up programs that will be used for cutting of materials. Variation of the processing parameters such as velocity, power, and gas mixture will be assessed.

· Analysis of results: This will involve use of optical microscope to determine optimal cutting and processing speeds.

· Cutting the keyring: Using the parameters determined a few key rings will be cut.

2.2. System B – Marking laser system

A laser marking system and Nutfield galvanometer will be used for the exercise. The following will be demonstrated: 

· Alignment Process: Setting up of a sample in the process region and location of laser beam focal position. 

· Laser ablation exercise: This involves machining the materials surface to determine the correct marking parameters.

· Marking the keying: Using the parameters determined marking of the key rings can be done.

2.3. System C – RF CO2 Laser

The laser used is a RF CO2 laser machine, which is coupled to a CNC stage operated. The following will be demonstrated and performed in the exercise: 

· Alignment Process: Setting up of a sample in the process region and location of laser beam focal position. 

· Laser ablation exercise: This involves machining the materials surface to determine their ablation rates. After alignment, the procedure will be performed using several different processing parameters. Parameters and their effects should be noted. 

· Analysis of results: This will involve use of optical microscope to determine hole depth. 

Note: In your report you will be required to provide information regarding pulse energy, fluence, etc for the parameters used during the exercise! 

3. Assessment

The assessment for the laboratory is on Blackboard. Please see blackboard for your online submission date. Feedback and marks will be given after all once all assessments have been submitted.

MSc Advanced Production Processess Laboratory Assessment (MACE 60132):

Question 1 (6): 

What was the maximum average power and units of each laser system used?

Question 2 (6):

Please summarise the experimental procedure and show how the samples looked after cutting. Show all the parameters used for laser cutting. Attached an annotated picture or diagram and describe the key areas of each experimental setup.

Question 3 (10): 

Please plot a graph of measured width against the average power, for Oxygen and Nitrogen. Please include any approximate errors and titles required (Example graph show below). State the experimental determined parameters used for laser cutting and why they were chosen.

Question 4 (Marking System 6):

Please summarise the experimental procedure for the Marking laser system and give the details of how the experiment was performed during the laboratory. Special mention to the parts of the laser system. Show all the parameters used when calibrating the laser and how describe how the colour was formed. Attached an annotated picture or diagram and describe the key areas of each experimental setup.

Question 5 (6): 

Calculate the fluence, which was used to mark your samples? Please show the Equations and working.

Question 6 (2): 

Please Insert a picture of the completed key ring.

Question 7 (4):

Please summarise the experimental procedure for the RFCO2 laser and give the details of how the experiment was performed during the laboratory. Show all the parameters when using the laser. Attached an annotated picture or diagram and describe the key areas of each experimental setup.

Question 8 (8): 

Please plot a graph of showing the change of depth at a result of increasing the number of pulses using an appropriate graph-plotting package. Showing how these results change with laser fluence, F?

Question 9 (8): 

Please plot and graph showing the change of etch rate, x against the change in fluence, lnF, using the beer lambert equation as demonstrated in the laboratory.

Question 10 (4): 

Determine the approximate threshold fluence F_T and absorption coefficient, α, (with units) from the graph plotted in question 9, by fitting a line of best fit through the points. The threshold fluence is calculated where line crosses the x-axis.

Question 11 (5):

Evaluate your contribution to the laboratory work and assess whether you functioned effectively as an individual and as a member of a team. How well do you think the entire team worked to accomplish the aims of the laboratory? (100-150 words)