As the use of computer design and control is increasing in modern manufacturing, so is the demand for computer-aided design (CAD) skills. CAD software is for manufacturing processes, such as CNC machining. Of course, that’s why it requires a mastery of the software tools.
CAD software packages deliver easy and fast ways to produce engineering designs. As with any technology, the human component remains essential to the design quality, completion time, and cost. If you currently work with CAD software for CNC machining, you might already be proficient. But, there is always room for improvement.
Once you have the ability to create CAD designs, it’s easy to upgrade your skills for CNC machining. It’s also important to avoid making mistakes that increase your production costs or completion time. If this is something you need to know, below, you will find six simple steps to help you achieve these goals.
6 Steps to Upgrade Your CAD Skills for CNC Machining
1. Try to avoid making walls that are too thin.
Wall features on designs are typically tricky. Although cutting tools used in CNC machines are made of hard materials, the tools still bend under machining forces. This happens because of the material they are cutting. This causes an undesirable rippled surface, bending, breaking or difficulty meeting part tolerances.
Overall, the thickness of the walls affect the rigidity of the product. The rule of thumb is – the taller your wall, the thicker it may need to be to reach the desired rigidity of the material. The minimum thickness to aim for with walls is 0.8 mm for metals and 1.5 mm for plastics.
2. Don’t design features that cannot be CNC machined.
It’s important to consider that not every feature you design can be machined. The fact is, some design features are not possible with a CNC machine. Therefore, you must consider which features are possible for a CNC machine. An example of this is a ‘curved hole’. For this feature and others, you must look for an alternative method such as electrical discharge machining (EDM).
3. Avoid unnecessary use of tolerances.
Designers must also use tolerance dimensions when possible. However, you must also take into consideration that unnecessary, or excessive use of tolerances increases the cost and delivery time of the machining process.
Tolerance standards vary from machine to machine So, if you don’t specify the dimensions for tolerance, the CNC machine automatically uses the standard tolerance dimensions. That’s why it’s very important to implement tight tolerances only when necessary. Do this to save both time and money.
4. Avoid designing features that require unnecessary machining.
You might also like to add features that serve an aesthetic purpose. It is important to remember that these parts might lead to unnecessary machining. In fact, doing affects both the machining time and the final production cost.
When designing, consider the process the machine uses to execute the shape. In particular, their might be a requirement to cut a specific shapein the middle of your material. Then, remove surrounding material to deliver the finished part. This approach adds significant time to your machining process. Interestingly, this results in wasting material, and drives the final production cost up.
It’s best to revise your design beforehand if you anticipate unnecessary machining, as it potentially cuts the production time and cost in half.
5. Always design cavities with precise depth-to-width ratios.
Another useful way to ensure your designs are of greater quality is to use an adequate depth-to-width ratio for cavities. If you design cavities that have a large depth, you run the risk of experiencing tool fractures, deflections, hanging, and complications with chip evacuation. Cavities that have a height that is 6-times larger than the tool’s diameter are too deep. Ideally, you must aim for a depth that is at most 4-times the size of the cavity width. For example, a 10mm cavity must not be more than 40mm deep.
6. Limit the thread length for CNC machining.
It is commonly known among engineers that the first few threads are essential for strong thread connections in a design. Therefore, adding threads that are too long is not a requirement, and is unnecessary.
When adding threaded holes to your machined parts, ton improve the design and ensure accurate execution you must select right thread length. The simple rule is that a thread should be no longer than 3 times the size of the hole diameter. In turn, when creating holes, make sure that they can be threaded and machined into your part. The rule of thumb for holes is to choose a diameter that is 75% of the hole drill size.
Once you become skilled in CAD designs, it’s easy to improve your skills and create refined designs. It is also important to avoid making mistakes that increase your production costs or take up unnecessary time. By implementing the guidelines we outlined in this article your designs will be of better quality and ensure a more efficient production process.
If you have any questions or suggestions, we always love to hear from you in the comments below. Also below are links that will take you to more fantastic articles about ALL things DESIGN for your home or business.
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