Wall thickness is an important part of CNC part design. It affects both manufacturability and strength. Choice of right thickness prevents machining problems and costly part failures. In this blog post you will find wall thickness guidelines, recommendations for different materials & best practices for outstanding CNC part design.
What is Wall Thickness in CNC Machining?
Wall thickness in CNC machining is the distance between inner & outer surfaces of a part. This dimension affects the part’s strength, weight as well as stability. For metals it can be as low as 0.5 mm and for plastics at least 1.5 mm. The chosen thickness determines how the part handles machining stresses and loads.
Also See: How to Avoid Deformation in Thin-walled CNC Machined Parts
Recommended Minimum Wall Thickness Guidelines
To design successful CNC machined parts you need to know the minimum wall thickness needed. Guidelines for wall thickness fall into two categories; “feasible minimum” and “standard minimum”.
Feasible minimum is the thinnest wall possible but only under perfect machining conditions. Whereas standard minimum is a balance between part strength and manufacturability and is greatly used in different industrial fields.
1. Metals
Feasible Minimum
With perfect process control and using materials such as brass or aluminum you can go down to 0.5 mm. But these thinner walls complicate machining & decreases rigidity.
Standard Minimum
Standard minimum wall thickness of 0.8 mm works for most metals. This value contributes to stable machining and keeps structural integrity. It also limits problems like massive deformation or vibration.
2. Plastics
Feasible Minimum
Under perfect conditions, some plastics like polycarbonate or ABS can go down to 0.3 mm in thickness. But this is only for special parts which don’t experience stress.
Standard Minimum
1.5 mm is the best for most plastics in CNC machining. This thickness stops warping & maintains structural integrity particularly for materials such as ABS, PP and PC.
3. CNC Turning Guidelines
In CNC turning don’t go below 0.5 mm wall thickness. This is because thinner walls will fail during machining. For best results keep angles above 30 degrees. Use a “roughing then finishing” method and leave a margin of 0.5 to 0.8 mm at first to limit deformation in the final step.
Our Swiss‐type lathes can produce 0.4 mm walls in brass connectors. Our electronics clients who need high volume accuracy mostly ask for this capability.
4. Factors That Affect Minimums
Different factors affect the minimum wall thickness which you can get in CNC machining:
Material Type
Aluminum is softer so you can get walls down to 0.5 mm. On the other hand titanium is harder so you need walls of at least 1 mm thickness.
Part Geometry
If a part has complicated curves or details then it’s harder to keep thin walls uniform.
Machining Ability
Advanced CNC machines with tight controls can make thinner walls and achieve greater tolerances.
Main Problems with Thin Walls
Thin walled CNC parts can reduce material usage and weight. But engineers have to deal with particular problems when designing these parts.
1. Structural Issues
Thinner walls are more prone to bending, warping or failing during handling or under load. Rigidity drops when height to thickness ratio increases or wall thickness goes below 2mm. So these thin walls can deform more easily.
2. Material Related Issues
Metals with thin walls can distort because of heat. In contrast plastics can warp or shrink as internal stresses release after cutting.
Thermal conductivity, hardness as well as elastic modulus of the material has a big role here. These properties decide how thin the walls can be and how stable the final dimensions will be.
3. Machining Issues
Thin walls deflect when cutting forces are applied. This deflection causes chatter and vibration which leads to dimensional errors and poor surface finish. Machining these parts needs slower speeds and causes more tool wear. Moreover tighter tolerances are harder to obtain.
Best Practices for Designing Outstanding Wall Thickness
1. Keep Uniformity
Keep wall thickness homogeneous throughout the design. Uniform thickness improves thermal stability, reduces internal stresses as well as removes material evenly. If the thickness changes suddenly the part may distort, warp or show unpredictable machining results.
2. Add Support Features
When designing thin walls add features like gussets, ribs or flanges for extra support. These features strengthen the part without making walls thicker. They reduce deflection and spread out stress so even thin walls can be strong.
RICHCONN’s engineering team uses modern CAD optimization to add these support features. In this way we not only keep the intended design but maintain the required proficiency and strength too.
3. Think About Height‐to‐Thickness Ratios
Use a wall height‐to‐thickness ratio of about 3:1 to make the part more rigid. This ratio helps stop vibration and bending during machining. For taller walls increase thickness to keep the part accurate and strong.
4. Design for Tool Access
Make sure tools can reach all features, particularly for parts with large depth‐to‐width ratios. Use the largest tool diameter and shortest tool length possible when designing parts. This reduces vibration during machining. And for deep cavities keep at least 4 times the undercut depth as clearance between machined walls.
5. No Sharp Internal Corners
CNC machining works best when you eliminate sharp internal corners. Always add a radius of 0.02‐0.05″ to every internal edge. So end mills can move through corners easily. This prevent stress from building up on the tool.
Material Related Wall Thickness Considerations
Material you choose has a big role in wall thickness when working with CNC machining. Different materials respond differently when you machine thin walls and each has its own set of limitations.
Metals
Aluminum, because of its machinability, can go as thin as 0.5 mm in those features which don’t bear loads. On the other hand stainless steel needs thicker walls, at least 1 mm, because it has a work‐hardening property and can distort.
Brass is stable at 0.5 mm but titanium needs a minimum of 1 mm to keep its strength and to avoid problems during machining.
Also See: Metal CNC Machining
Plastics
Plastics need thicker walls as compared to metals because they are less strong. Polycarbonate and ABS can go as thin as 0.3 mm under perfect conditions but for consistent results 1.5 mm is better. High‐performance polymers like PEEK may need at least 2 mm of wall thickness to avoid warping during machining.
Also See: Plastic CNC Machining
Tools and Resources for Designers
For designers, there are many available resources and tools to help design parts for CNC machining. Below are some main resources to help in design workflow.
Design Guides
You can find detailed CNC machining design guides from reputable sources like Richconn, Protolabs, Xometry and Weerg. These sources give recommendations for wall thickness for different materials, tips as well as best practices to improve manufacturability and part geometry.
Consult with Machinists
Working with experienced CNC machinists or consulting with specialized companies gives you the opportunity to review your designs, choose the right materials & fine‐tune tolerances. They can solve difficult wall thickness problems and assure your parts meet both manufacturability and usability requirements.
Many designers use RICHCONN’s free DFM review service. This service checks thin wall designs against a database of over 12,000 completed projects.
Simulation Software
You can use simulation tools such as Vericut and Autodesk Fusion‐360 for model machining, adjusting wall thickness and for predicting tool deflection. By simulating you can detect potential issues before manufacturing starts. This improves part quality and reduces risk of errors.
To Sum Up
Wall thickness is very important to get the right balance between part strength, affordability & manufacturability in CNC machining. You have to follow guidelines for particular materials, use advanced tools and apply proven best practices so you can get high quality parts.
To manufacture which require outstanding wall thickness, get in touch with Richconn’s team of CNC Machining experts today.
Related Questions
How does wall thickness affect CNC machining cycle time and cost?
Thinner walls mean less material but mostly longer cycle times and higher costs. This is because machines have to run slower so errors are more likely and tooling is more complicated. In contrast thicker walls mean more material so higher material cost but faster machining.
Are there risks of over engineering wall thickness in CNC part design?
Yes making walls too thick means heavier parts and wasted material. Costs go up and machining takes longer. Moreover these changes don’t always result in better part performance.
Can post‐machining processes like coating or anodizing affect wall thickness tolerances?
Yes post‐machining works like painting or anodizing add extra layers to the part. These layers increase the wall thickness. So if design doesn’t account for this, the final tolerances will be affected.
How does toolpath strategy affect success of thin wall machining?
A correct toolpath reduces tool vibration and deflection. This improves surface finish and accuracy on thin walls. It does this by reducing heat buildup and cutting forces.
How do tolerances relate to thin walled CNC parts?
Machining thin walls is hard as it increases vibration, warping & tolerance problems. So designers have to use looser tolerances or adjust the design.
What are the implications of wall thickness in multi axis CNC machining?
Multi‐axis machining can create complicated shapes. But thin walls still present challenges because tool access is more difficult and vibration increases. So careful planning and fixturing is needed.
Are there any ISO or industry standards guidelines for CNC wall thickness?
Yes ISO 2768‐1 sets general tolerance standards like ±0.2 mm for plastics and ±0.05 mm for metals. But the best wall thickness depends on material type and its application.
