3. Computer Controlled Cutting

Laser Cutting Machines at Jigme Namgyel Wangchuck Super Fablab

JNWSFL, Thimphu, Bhutan has two types of trotec laser machines (trotec Speedy 400 flexx laser cutter and trotec Speedy 100 laser cutter) and MR. CARVE Engraving machine.

1. Trotec Speedy 400 flex laser cutter:

Specifications for trotec Speedy 400 flex laser cutter

reference link here

1. Trotec Speedy 100 laser cutter

Specifications for trotec speedy 100 flex laser cutter

reference link here

1. Mr Curve

reference link is here

Laser Safety Measure

• Never leave the laser machine unattended while the system is operating

• Always have a fire extinguisher available, as the laser beam can ignite the flammable materials

• Do not put any flammable materials inside the machine or immediate surroundings of machine

• Be aware of all the laser safety stickers on the machine and follow them

• The system must be used only by authorized and trained personnel

• Avoid electrostatic charging during cable connections and plug in.

• Do not operate the laser machine without adequate exhaust system

• Remove debris from the exhaust blower and duct system.

• In case of broken lens: avoid direct skin contact and inhaling

• EMERGENCY-STOP: on any risk: Lift the cover lid

The image below shows Safety equipment that we have in our lab for laser machine. Currently our firextinguisher is taken for the refill, for which we were not able to take the picture.

For this week group assignment we chose to use speedy 100 flex

Characterization of lasercutter’s focus, Power, Speed & Rate

To ensure smooth and accurate results for laser characterization:

1. Clean the Working Area- Remove all the dust, debris and left over material from the laser bed and also ensure the bed is flat for accurate engraving and cutting

1. Clean the Laser Lens-Use a soft cloth or lens-cleaning wipes. And also apply lens cleaner if necessary and gently remove any smudges or dust.

   Steps to Clean the lens:

   • Turn off the machine

   • Loosen all the screws

   • Take out the len and the mirror.

   • Avoid using regular tissue or cloth, as they may scratch the lens. Use the isopropyl alcohol or the lens wipe as shown in the image below.

   • Clean the lens using the lens wipe.Make sure all the dust and debris has been removed.

   

   • Once done with cleaning, connect the screws back and tighten it

2. Inspect Ventilation and Exhaust- ensure that the exhaust system is functioning and removing fumes and smokes

3. Beam alignment- to ensure the laser beam is properly aligned

After doing all the steps above, Now proceed for the next steps to check the cutting and engraving settings

• Place the work piece to the left corner of the bed. Move the nozzle to the middle of the work piece to set Z axis.

• The next crucial step involves calibrating the z-axis to ensure precise laser focusing. Using the focusing key, position the square side onto the edge of the laser head. Gradually elevate the z-axis until the key gently slips off the laser head.

The image above shows the key to set the Z axis

* Or You can do the autofocus by pressing both the Z key(operational) at once, as shown in the image below

• Calibrates the x, and y axis to ensure accurate and consistent result

• Open the Inkscape the created different colour fill shapes. After filling the shapes with different colors and the colors settings.For green colors we gave the RBG colors setting of R-0,B-255,G-0. We follows the same procedure for all the assign colors.

• Open Trotec JC > settings > Material template settings. Here, assign different functions and parameters to each of the colors.

Finding the right setting for the laser Engraving;

Power Variation:

First we kept the varying power values with constant speed and pulse per inch(PPI)

Image below shows how different power affects the engraving

Velocity Variation:

After finding the right power setting than we tired for the varying velocity with constant power value at 95 and PPI value at 1000Hz.

PPI Varaition Lastly after finding the setting for the Velocity, we tired for the varying PPI keeping constant power of 95 and Velocity of 55.

Image below is the result of velocity and PPI <<<<<<< HEAD =======

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Conclusion & Result

From the above setting we concluded how different power and velocities affects the engraving. Higher power results in draker engraving, and also with lower speed at the same power could lead to burnt. However the Pulse per Inche variation doesnt have much impact in the engraving.

Finding the right Power and velocity is crucial for the laser engraving.

Finding the setting for the laser cutting

Power Variation

We also tired to do the test cut using different power setting at constant speed and PPI

Velocity Variation

Keeping power and pulses constant at 55 and 1500, respectively. Varying the speed parameter from high to low across different colors.

Pulse Variation

Maintain power and speed constant at 55 and 0.5, respectively. Adjust the pulse parameter across different colors while keeping speed and power settings consistent.

Conclusion & Result

From the above setting we concluded that, When you use a higher power value, then you can increase the speed because the laser needs less time to burn through the material. We also conclude that as the speed decrease the material start buring because the laser has more time to burn through.

Generally we would recommend choosing the lowest possible power value and choose the fastest possible speed for cutting.Even worse, running high power values at slow speed tremendously increases the risk of your material catching fire.

We can also concluded the setting that makes the perfect cutting.

Understanding the kerf

Next, to study the kerf and joint clearances of the laser machine we took cardboard of 5mm thickness and cut two combs out of it. In order to calculate the kerf, we used a kerf generation tool which was made by Atsufumi Suzuki a fablab Kamakura graduate.

Firstly we opened the kerf generation tool and entered our parameters

We used the cardboard of 5mm thickness and the gaps in the combs ranged from 4.4 to 5.4 with the increments of 0.2mm to determine the best fit.

   Image below shows comb that is cut using our laser cut

After finished cutting two nos of combs we took out and started fitting both combs together to see best fit and we found that 4.8mm gaps provided the best fit, ensuring optimal joint clearance.

So, on 5mm thickness cardboard 4.8mm gaps provided perfect fit for the joints.

To calculate the kerf

We measured back the 5.4mm gap of the comb using vernier caliper and found that it measured 5.65 in vernier calliper.

5.65 - 5.4 = 0.25 0.25/2 = 0.125 therefore kerf = 0.125