Computer controlled cutting¶

Group assignment:¶

Characterize your lasercutter’s focus, power, speed, rate, kerf, joint clearance
Document your work to the group work page and reflect on your individual page what you learned

Laser cutting¶

Principles of laser cutting¶

Laser cutting is a manufacturing process that involves cutting material using a large amount of laser-generated energy concentrated on a very small surface area.

Laser cutting is based on the use of a concentrated laser beam to locally heat and melt the surface of a material, enabling it to be cut with great precision. The process involves generating a laser beam, concentrating it through optics, focusing it on the material to be cut, and moving the beam in a controlled manner along the contour of the workpiece according to the instructions of a computer program. An assist gas is often used to remove debris and ensure a clean cut. Laser cutting is widely used in various industries because of its speed, precision and ability to handle a wide variety of materials.

Cutting width in laser cutting is mainly influenced by laser power, beam travel speed, material thickness and type, and the optical properties of the material. Higher laser power tends to produce a wider cut, while faster beam speed can reduce it. Material thickness and optical properties also affect cutting width by modifying the way the material absorbs and dissipates laser heat. In short, cutting width depends on a variety of parameters and requires careful optimization to achieve accurate results.

Presentation of the machine

In our laboratory (Fab Lab INP-HB YelloLab), we use the Epilog Laser Edge 36 for a variety of applications. This cutting-edge technology enables us to make precise, efficient cuts in a variety of materials, from metal and plastic to wood and even fabrics. Thanks to the controllable power of the laser and the flexibility of its parameters, we can adjust the depth and width of the cut to the specific needs of each project. This enables us to achieve high-quality results, while ensuring high precision and repeatability in our manufacturing processes.

this table shows some specifications of our machines

Specifications
Laser source	CO2 : 80W
Speed control	0.1-100% (Adjustable)
Power control	1-100% (Adjustable)
Resolution	75 – 1200 dpi
Software	Epilog Dashboard; Inkscape
Work Area	36″ x 24″ x 10″ (914 x 610 x 254 mm)
Materrial thckness	10″ (254 mm)
Laser tube wattages	CO2: 60 watts
IRIS camera System	2 overhead
Motion system	Brushless DC Servo Motors

For more information, click on: documentation

as with all other machines, there are safety precautions to be observed.

Safety

When using laser cutting, it’s essential to take safety precautions to protect operators and prevent accidents. Read the safety instructions before use. the manual can be found at Here

⚡Laser cutting safety

Stay with the laser: Never operate the laser system while unattended.
Keep the area clear: Clean around the machine and keep the area free of clutter, combustible materials, explosives, or volatile solvents such as acetone, alcohol, or gasoline.
Be prepared with a fire extinguisher: Always keep a properly maintained and inspected fire extinguisher on hand.
Use Air Assist: Always use the system’s Air Assist feature when vector cutting.
Use caution when vector cutting: Many materials have the potential to suddenly burst into flames when cut with a laser – even materials that may be very familiar to the user. Always monitor the machine when it is operating.
Clean the laser: A buildup of cutting and engraving residue and debris is dangerous and can create a fire hazard in its own right. Keep your laser system clean and free of debris. Regularly remove the Vector Cutting Table to clean any small pieces that have fallen through the grid.

Setting focus

Engraving focus refers to the process of adjusting the position of the laser lens relative to the work surface to achieve optimum laser beam focus. The aim is to ensure that the focal point of the laser beam is exactly on the surface of the material to be engraved. Accurate focus is crucial to guaranteeing clean, precise engraving results, as it affects the depth and sharpness of the engraved mark. By adjusting the focus, the energy density of the laser beam on the material surface can be optimized, resulting in uniform, high-quality marks. Engraving focus is often adjusted by moving the laser lens up or down relative to the material surface until the focal point is correctly positioned.

automatic focusing :

Automatic focusing, also known as autofocus, is a feature in laser cutting and engraving systems that automatically adjusts the focal length of the laser beam to ensure optimal focus on the material being processed. This feature is particularly useful when working with materials of varying thicknesses or when cutting or engraving on uneven surfaces. In an automatic focusing system, sensors or cameras are used to detect the distance between the laser head and the material surface. Based on this information, the system adjusts the position of the focusing lens to achieve the desired focal point. This adjustment is typically done in real-time during the cutting or engraving process, ensuring consistent and precise results regardless of changes in material thickness or surface irregularities. Automatic focusing systems help streamline workflow, improve efficiency, and enhance the quality of laser cutting and engraving operations by eliminating the need for manual adjustment of the focal length. This feature is especially beneficial in production environments where rapid and accurate processing of materials is essential.

the image below is taken from the yellolab fablab group site

manual focus :

Manual focusing in laser cutting and engraving systems requires manual adjustment of the focusing lens position to obtain the optimum focal point on the material surface. This usually involves moving the lens up or down relative to the material surface until the focus is correct. This operation is carried out before starting the cutting or engraving process, and may require trial and adjustment to obtain the ideal focus for the thickness and characteristics of the material. Although less automated than automatic focusing, manual focusing still offers flexibility and precise control over the laser engraving or cutting process.

for further details, please refer to the manual on page 123, 124