DfM: 2Laser Cutting
Criterion E and F of your IA requires you modify your design so that it can be commercially manufactured.
These modifications should be based on the Design for Manufacturing approaches.
Your work in Criterion E should show examples of how your design is modified to optimize the commercial manufacturing process you have chosen.
If you have chosen laser cutting as one of the commercial processes in Criterion E1 of your IA, you will need to show how your design would be modified to accommodate this process. Laser cutting is a complex process with many factors to consider. We've summarized the main considerations to take into account when modifying your design.
Information about the BHA laser cutters is here
Advantages
Complex shapes can be cut easily and accurately
Relatively faster compared to other CAM cutting processes.
Wide variety of materials, and at different thicknesses, can be cut.
Can incorporate cutting, etching, and rastering into one process
Very accurate cutting, ideal for precision parts
Little to no clean up after the cutting (this also depends largely on the material that is cut)
Disadvantages
Higher energy use
Requires specialized equipment and training.
Some materials cannot be used due to the high heat of the laser and the toxic gases produced.
Use Consistent thickness of materials and reduce material types
The cutting of flat panels is by far the most common application for laser cutters. To optimize material use and cutting times, designs should be modified to produced from similar materials and thicknesses. This strategy will simplify production and assembly.
Strategies for commercial production
Consider re-designing your product with common materials and thicknesses that can be joined together with CAD joints (see below).
For example, a cabinet design might be modified so that all pieces are manufactured out of 15mm plywood
Use a CAD joint
There are many types of joints that can be used with laser cut parts. Incorporating the joints into the actual design will increase accuracy and simplify assembly.
Refer to this chart of CAD joints to determine the best type of join for your purposes.
Strategies for commercial production
Consider using a CAD joint that allows for disassembly, assembly without tools (i.e. it snaps together), or assembly without adhesives (glue). Any of these strategies will optimize your DfM goals.
50 Digital Joints is a valuable resource for different types of joints. Red boxes highlight joints that can be manufactured using a laser cutter. Check out the full poster here
digital joints.pdf
Nesting
Nesting is the process of placing the parts of a designing in a way that optimizes material use, reduces waste, and reduces manufacturing time.
Strategies for commercial production
Consider how the pieces of the design can be arranged to reduce waste and cutting time.
Consider how the dimensions of the design might be modified to better use standard sizes of sheet material. For example, if the standard size of plywood is 120mmx2400mm, you might modify the size the design to better use this material and reduce waste; Or, you might arrange the pieces so that as little waste as possible is produced.
Use a press fit
Fit refers to how tightly the pieces fit together.
A looser fit allows a product to be easily disassembled and reassembled. However, the joints may not be very secure or precise.
A tight fit ensures a secure fit without the use of adhesives or hardware. However, this may require more force to assembly, and could increase assembly time. In addition, the greater precision required can increase production time.
The main consideration with fit is the kerf of the laser and how this influences the final dimension of the piece (see kerf below).
Strategies for commercial production
In most cases, a Press Fit is ideal. Do a test and determine if your dimensions, kerf thickness, laser cutter settings, and material will produce a press fit.
Consider the kerf of the laser cutter
Lasers typically follow a vector line to create a cut. As the laser follows the line, it is removing material. The laser has a diameter. The diameter of the laser cut is called a kerf. The kerf differs depending on the settings of the laser cutter, speed, and material. Generally, the thicker the material is, the slower the laser has to move - this results in a wider kerf.
For designers, this means that the dimensions of some shapes could be reduced by a fraction of a millimeter. This smaller than planned size is critical when designing complex designs that need to fit accurately together. This is most noticeable in joints, as the material lost to the kerf can create gaps.
Strategies for commercial production
Consider doing a test cut in the material of your choice to ensure proper fit. Adjust the dimensions of the cut in the software to compensate.
