CNC machining covers a huge range of uses and is offered for the construction of complex parts and prototypes, while is the most economical solution compared to machining of other types.
However, the cost and quality outcome of these depends on the design stage and the strategy that is decided on to implement a prototype.
However, by knowing some specific and tested design elements, you will be able to reduce the time, complexity, and eventually the cost of processing.
Here we mention 7 useful tips and best practices, the implementation of which has shown - in our experience - that leads to the best economic result.
1. Select a suitable material
Initially, the type of material selected has a high-cost impact. CNC machine tools can handle everything from plastic to metal. However, there are materials that are easier to process than others. Plastic, for example, has various types, has many uses and is easily machined. PP or POM, for example, is relatively difficult to process and more prone to distortions, which means that processing is more complex and costs more.
Some other thermoplastics have very good mechanical properties and resistance to high temperatures, such as PEEK; however, they have a very high purchase cost, and often exceed the manufacturing needs, thus raising the overall cost unnecessarily.
The metals also offer different types of machining. Aluminum is a soft metal, easy to cut and fast on the machine tool.
Steel is tougher material and even tougher for machine tools. This is often reflected in the cost of the components. The next thing to consider is that of geometry, where there are so many different aspects to consider that it would be impossible to list them.
2. Examine the corners of the drawing
CNC machine tool cutting tools are cylindrical, therefore smaller diameter cutting tools will leave a circular section in the corner. In case that you need absolute angles, this will require you to complete the process, either manually, by electrodeposition or other methods (e.g. broaching) that will be costly.
3. Avoid deep packages
The deep packages lead to tool collision, leaving the surfaces with imperfections. If you can avoid these elements the better, if again not; the best relationship between length and depth is 4: 1.
4. Avoid thin, high walls
Slim and tall wall elements also add degrees of difficulty to machine tooling as they are easy to destroy. In addition, they cause vibrations on the cutting tools and bad finishing surfaces on the component produced.
For the above reasons, they are not preferred by engineers.
5. Divide the construction into separate sections where possible
In addition, for some components it may make more sense to separate them into separate parts if they are to be machined.
Usually, where the design of a solid component serves the highest mechanical strength and ornamentation, as you can divide it into individual parts you will certainly save money on both costs and processing time.
Compare areas 1 and 2 in the picture below. In this case, it may make sense to separate the part as shown in area 2, as it makes the machining process more difficult for the machine, increases the initial cost of materials, and requires additional machine adjustment.
6. Avoid "closed" tolerances that match your application
What usually increases the cost of a construction is the tolerances required by the components.
Obviously the more stringent the desired tolerance is, the more care and attention it needs when handling the component. Extremely demanding tolerances on certain components may also require the construction of clamps and jigs to hold and orient the piece or even the use of specialized cutting tools that will increase machining time and cost, e.g. component relatively small but "expensive" due to tolerances ±.
7. Use standard threads and holes
The use of standard sizes applies to both threads and holes. If you need threaded holes, try to follow the standard thread as much as possible.
Buying tools for non-standard threads can lead the cost to increase and the raise of waiting time of the specialized tool because manufacturers do not stock them or make them on demand. It may also require the provision of a special latch that will again incur costs.
In conclusion, proper design is necessary in order to save processing time and reduce the final cost of the original. All the above practices contribute to the proper planning and the best economic result.