How To Improve CAD File Design for CNC Machining Parts
Most CNC machining projects start out as a drawing in CAD software. This software makes it easier to for engineers to design their projects. However, they seem to not fully optimize the capabilities of the CAD file design. It results in defective CNC machined parts not useful for the target market. Despite CNC machines being highly precise and accurate, they still rely on the effectiveness of a CAD file design. At Creatingway, we have a solution as to how designers can get the most out of this AI-powered tool.
Here Are Some of the CAD File Design Tips to Share
Internal Edges CAD File Design
Internal edges of a design may cause stress on the machine tool, especially depending on the shape. Most cutting tools are cylindrical and thus only capable of making round internal edges. It is therefore necessary to add radii on the internal edges of your CAD file design. The internal edges should not stress the tool too much. Otherwise, the tool will experience more wear and tear. We recommend a radius that is 1.3 times that of the milling tool radius. For instance, a tool with a radius of 5 mm needs to have an internal edge radius of 6.5mm. this additional radius helps in reducing tool stress and increasing cutting speed. For 90 degree internal edges, you could add an undercut to the design to achieve this feature while machining.
Some engineering projects need to have thin walls in their design to be functional. For instance, in making whistles and drone parts. However, avoiding extremely thin walls helps improve the overall CAD file design. Statistics show that part stiffness is directly proportional to wall thickness. Thus, lowering the wall thickness causes the part to be less stiff. During the machining process, the parts experience tool vibrations and need to be stiff enough not to vibrate too. Therefore, achievable accuracy is lower once the part is not stiff. At Creatingway, we recommend a standard minimum wall thickness of 1.5 mm for plastics and 0.8 mm for metals. Though, we can still process projects that still need lower wall thickness than the standard sizes. We use metal fabrication for such projects.
Cavity CAD File Design
When designing cavities, you should consider the depth to width ratio. We consider cavities six times higher than the tool diameter deep. Therefore, the max depth cavity should be four times the cavity width. For instance, a 10 mm wide cavity should not be more than 40 mm deep. Very deep cavities cause problems during machining. It either leads to tool deflection or tool hanging. Also, chip evacuation becomes difficult.
CNC Machine Features
Not every CNC features can be machined. Also, having pointless design features makes it hard to machine. Designers need to know the CNC machine’s limits. This assists them in making producible features in the file design. For instance, when using a CNC mill, drill, or lathe, it is hard to machine a curved hole feature. However, we may use an EDM to machine such impossible machine features.
Lowering the number of unnecessary aesthetic features helps improves a CAD file design. You should consider the process to be used in making the feature. Is it a 3-axis or 5-axis machining process? Also, what amount of material should be removed from the workpiece for the feature to be created. Paying attention to such details makes you prioritize the necessary features that need to be accurate. Aesthetic features can undergo post-machining processes. Such as electro-polishing to get a smooth and shiny smooth surface.
Number of Tolerances
CAD file designs often have their tolerance dimensions specified. This helps the manufacturer know the limits during machining. Also, CNC machines use a standard tolerance for designs without tolerancing dimensions. However, when there is over-tolerance in the design, it leads to an increase in time and cost. It is thus important to only specify tolerances where necessary. Also, maintaining one tolerance dimension assists in saving time.
Texts and Lettering
Texts and lettering are important in labeling parts of the project. However, they increase the cost when CNC machined. Alternatively, texts could be painted during post-processing. To save on costs, the design requirements for the texts should be engraved. It will result in less removal of material. The second tip is the use of Serif font with 20 points for lettering in the design. It is because of fewer strokes in the font and the size of the letter is adequate.
Sometimes it is hard to machine small features due to the CNC tool’s limit. Most CNC machines have a minimum tool diameter of 2.5 mm. Any feature less than 2.5mm is small. Micromachining however can machine features up to 0.5mm. But they are costlier and take time. The CAD file design should only have small features when necessary. Contact Creatingway now for CNC machining services.
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