Understanding Wall Thickness for CNC Machined Parts

When it comes to designing parts for CNC milling, one of the most critical parameters you need to consider is wall thickness. In this article, we will dive into the most important things to understand about wall thicknesses and focus on how they affect the overall manufacturability of your custom part.

What Do We Mean by Wall Thickness?

The “wall thickness” of a CNC milled part refers to the minimum and maximum thickness that walls of a part can have when being produced through the milling processes. This dimension is crucial for ensuring the structural integrity and functionality of the part.

Why Wall Thickness Matters

While designing machined parts, the general inclination is to make features and walls as thin as possible. However, making the walls too thin can have significant drawbacks. Despite their apparent benefits, thin walls reduce the enclosure’s strength and stiffness. This increases the possibility of vibration during the machining process. This vibration may lead to material failure or “poor” surface finishes.

How Thin is Too Thin?

A common question arises at this point: “How thin is too thin?” A general rule of thumb suggests that CNC machined walls should maintain a minimum width of 60 thou (thousandths of an inch). However, this is not a one-size-fits-all rule, as it largely depends on the height and surface area of the thin feature – especially if this feature is connected to thicker pieces on each/either end of the design.

If a wall measuring less than 0.06 of thickness is one-eighth of an inch in height and one inch long, it probably won’t be a problem.

However, if the same wall thickness is 1.5 inches high and five inches long, then challenges may arise. Other factors can also influence this, such as whether the wall is supported on both ends or not.

It’s worth noting that walls thinner than 0.06 are possible at times however, this may also increase the part’s complexity. Additionally, for thinner walls with a favorable height to width/length, than there may be no issues with manufacturability.

When it comes to CNC machined parts, the concept of a wall being “too thick” is less discussed compared to walls being too thin. However, excessively thick walls can present their own set of challenges and inefficiencies during the machining process.

Balancing Thickness, Cost, and Tolerance

To balance machining time, cost, and design accuracy, it’s advisable to maintain a minimum wall thickness of 0.06 (60 thousandths of an inch). If your part has deep pockets, a thicker wall would be more appropriate. If walls are too thin, they may move during the machining process. This will cause the finished part to be undersized, thus falling outside the standard fabrication tolerances of plus or minus five thousandths of an inch. To rectify this, either tolerances would need to be relaxed or the wall would need to be made thicker.

Concluding Thoughts

In the world of CNC machining, wall thickness should not be overlooked. Ensuring the correct thickness will result in a CNC machined part that meets specifications and has an excellent finish. However, if you’re grappling with a CNC part design and the wall thickness falls outside of our recommendations, chat with us. Our team will work with you to ensure we meet the specifications of your project.

To learn more about this topic, be sure to check out this full tech tip video for more information. Stay tuned for more educational content on CNC machining for Protocase.

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