CNC Machining of Parts with Minimum Wall Thickness and Related Part Design Guide
- CNC Machining of Parts with Minimum Wall Thickness and Related Part Design Guide
- CNC Machining of Parts with Minimum Wall Thickness
- Thin-walled CNC machining design guidelines
- CNC Thin-Wall Machining Minimum Thickness Manufacturing Guide
- CNC machined parts wall thickness design
- Minimum wall thickness design parameters for CNC machining of parts made of various materials
- The main causes of warping and deformation during CNC machining of thin-walled parts
- Advanced strategies for CNC machining of parts with minimum wall thickness
- The best material for CNC machining of thin-walled parts
- How to reduce the cost of thin-walled CNC machining : A summary of Elimold's team's experience
- Common Manufacturing and Design Errors in CNC Machining of Thin-Walled Parts
- Obtain thin-walled CNC machined parts through Elimold in just 3 steps
- Article Summary
Components with varying wall thicknesses are increasingly used in a wide range of products. Low-wall-thickness parts are lightweight, material-saving, and compact, while high-wall-thickness parts are the opposite. Thin-walled parts are extremely difficult to manufacture, and companies offering custom CNC part manufacturing services may not be able to handle them because thin-walled structures are prone to deformation during machining, making it difficult to guarantee the final part’s quality.
The CNC machining of thin-walled parts has always been a challenging problem. Moreover, these parts are typically manufactured using CNC machining, requiring experimentation with workpiece clamping, tool geometry parameters, and program development to effectively overcome deformation during machining and ensure machining accuracy.
Wall thickness is a crucial aspect of CNC part design. It affects both manufacturability and strength. Choosing the appropriate thickness can prevent machining problems and costly part failures. In this article, you will find design guidelines for thin-walled parts, recommendations for different materials, and best practices for optimal CNC machining of minimum wall thickness.
CNC Machining of Parts with Minimum Wall Thickness
Wall thickness refers to the distance between the outer and inner surfaces of a part. Although it may seem like a simple dimension, wall thickness is one of the most critical aspects of part design. The wall thickness of CNC-machined parts directly affects their mechanical properties, including strength, stability, and resistance to external forces. Furthermore, wall thickness plays a crucial role in the manufacturability of parts. Whether designing parts for lightweight applications or high-strength structural uses, wall thickness influences not only the part’s strength and performance but also material selection, manufacturing time, and cost.
However, CNC machining of thin-walled parts with a thickness as low as 0.5 mm often results in severe warping, chatter marks, and a decrease in surface finish. Failure to effectively control cutting forces and residual stresses early in the design phase inevitably leads to high scrap rates and budget overruns during production. Having handled thousands of high-precision aerospace and medical orders, we have developed specific toolpaths, feed rates, and workpiece clamping strategies to prevent warping. Mastering these manufacturing limits is crucial for engineers and procurement teams seeking reliable tolerances without trial and error.
Thin-walled CNC machining design guidelines
| Feature Aspect Ratio Control | For suspended or slender thin-walled structures, the ratio of wall thickness to depth should be strictly controlled. The height of the thin wall should generally not exceed 3 to 5 times the wall thickness (or base thickness). If this range is exceeded, vibration during tool cutting will cause the part to chip or break. |
| Avoid abrupt changes in wall thickness | The wall thickness of the part should be kept as uniform as possible inside and outside, and the transition between thicknesses should be done with radii or bevels. Abrupt changes will cause residual stress concentration, which will easily lead to warping during cutting or heat treatment. |
| Ribs & Gussets | When thin walls must be used to reduce weight, avoid designing large, unsupported, isolated thin walls. Adding reinforcing ribs to support the thin walls effectively improves overall rigidity and suppresses cutting vibration. The thickness of the reinforcing ribs should be 40% – 60% of the main wall thickness to prevent uneven shrinkage that could cause shrinkage cavities or dents. |
| Inner corner and bottom corner design | Sharp corners can cause stress concentration and restrict toolpath, resulting in low efficiency in thin-wall machining. The internal corner radius should be set to at least 1.2 times the tool radius (recommended radius ≥ 2 mm). The bottom corner of the cavity should not be designed as a sharp 0 mm; it is best to reserve R1 – R3 mm to avoid high “corner clearing” machining costs. |
| Layered/Multi-step tooling strategy | Machining extremely thin walls (especially those less than 1 mm) cannot be completed in a single cut. Allowances should be made in the CAD design to inform the machining plant to use multiple light cuts (reducing the depth of cut and feed rate per cut) or cryogenic machining methods to prevent elastic deformation (tool deflection) of the thin wall under high-speed cutting forces. |
CNC Thin-Wall Machining Minimum Thickness Manufacturing Guide
The Elimold team has summarized the challenges of manufacturing thin-walled parts using CNC technology and provided best practices for designers and engineers. Ultimately, you will have a clear understanding of how to balance design requirements and machining capabilities to ensure the production of high-quality parts. Below is our summary of guidelines on minimum thicknesses for CNC thin-walled machining.
| Core Mechanics of CNC Thin-wall Machining | When a part employs a thin-walled design that results in a significant decrease in stiffness, the material becomes highly susceptible to deformation under cutting forces. Therefore, the fundamental problem in CNC thin-wall machining lies in structural stability, not merely material removal. Material stiffness is proportional to the cube of its thickness. The stiffness of a 1 mm thick wall is far less than one-fifth that of a 5 mm thick wall. Even minute cutting forces can lead to enormous deformation. |
| The DFM Golden Rule for Thin-Walled CNC Parts | To ensure that thin-walled precision CNC machined parts meet tolerance requirements, strict geometric constraints must be adhered to. For every 0.5mm reduction in wall thickness, the machining difficulty increases exponentially, not linearly. “Savings” made during the design phase often translate into several times the additional cost during the machining phase. |
| High thickness ratio (H:T) limit | Generally, the upper limit for the unsupported thin-walled profile ratio is 15:1. A wall height of 1 mm in thickness must not exceed 15 mm. Exceeding this ratio requires highly specialized molds, which significantly increases costs and makes maintaining standard tolerances virtually impossible. |
| Rib optimization | In the design of thin-walled CNC parts, stiffeners provide critical support, but their design also has limitations. The thickness of the stiffener should only be 50% to 60% of the main wall thickness. Stiffeners exceeding this thickness will cause shrinkage marks or warping on the other side of the part. Furthermore, the height-to-width ratio of the stiffener must be less than 3:1 to prevent vibration during machining. |
CNC machined parts wall thickness design
wall thickness design of CNC parts is also closely related to the part’s geometry. The following are validated design experience values. (Cost Trap: Many engineers we’ve encountered have made the wall thickness 1mm or even thinner in order to “reduce weight.” As a result, machining costs tripled, the scrap rate increased by 15%, and delivery time was extended by one week. If weight reduction is a critical requirement, consider topology optimization or hollow structures first, rather than blindly thinning the wall thickness.)
| Design parameters | Experience points | illustrate |
| Wall thickness to adjacent feature height ratio | ≥1:5 | The height of thin-walled sections should not exceed five times the wall thickness. Exceeding this ratio dramatically increases the risk of processing vibration and deformation. For example, for a wall thickness of 1 mm, the height of adjacent features should not exceed 5 mm. |
| Unsupported wall height vs. wall thickness | ≤4:1 | Suspended thin-walled structures (without material support on one side) are more prone to deformation. It is recommended that the wall height not exceed four times the wall thickness. If it does, consider adding reinforcing ribs. |
| Wall thickness transition | Gradual transition, slope ≤ 45° | Abrupt changes in wall thickness can cause stress concentration and uneven material flow (especially severe in castings). It is recommended to use bevels or fillets to transition between thickness changes. |
| Reinforcing rib thickness | Connecting to 60–70% of the wall thickness. | The reinforcing ribs should not be made as thick as the wall, otherwise material buildup and stress concentration will occur at the junctions. |
| Uniform wall thickness principle | Wall thickness difference ≤25% | The wall thickness of the same part should be kept as consistent as possible. If the difference is too large, the thin-walled areas will experience uneven cooling/stress, making them prone to warping. |
| Impact of thin-walled cost | For every 0.5mm reduction in wall thickness, the cost increases by 20–40%. | Thin-walled parts require more tool passes, lower feed rates, and more setups, resulting in a significant increase in machining time. If you can make 2mm, don’t make 1mm. |
Minimum wall thickness design parameters for CNC machining of parts made of various materials
Different materials vary greatly in rigidity, cutting force, and thermal expansion, resulting in different minimum wall thicknesses. The table below shows empirical values summarized from tens of thousands of orders in our workshop. (The minimum wall thickness parameters below are summarized by the Elimold team and are applicable to conventional CNC milling. For slender, thin-walled parts (height exceeding 5 times the wall thickness), even if the minimum wall thickness requirement is met, special processes may be required (such as step-by-step milling, tooling, and reduced cutting parameters). For complex thin-walled parts, it is recommended to discuss feasibility with the machining team during the initial design phase.)
| Material | Minimum wall thickness | Recommended wall thickness | The consequences of being too thin |
| Aluminum alloy (6061/7075) | 0.8 mm | ≥1.5 mm | Excessive milling vibration, surface rippling, dimensional deviations, and deformation after anodizing |
| Carbon steel (1045/4140) | 1.0 mm | ≥2.0 mm | High cutting forces lead to tool deflection in thin-walled applications, excessively thick dimensions, and accelerated tool wear. |
| Stainless steel (304/316) | 1.0 mm | ≥2.0 mm | The material is subject to severe work hardening, and thin-walled areas are more prone to deformation and surface hardening. |
| Titanium alloy (Ti-6Al-4V) | 1.2 mm | ≥2.5 mm | The cutting temperature is extremely high, heat dissipation is difficult in thin-walled structures, and thermal deformation leads to scrapping. |
| Copper alloy (H62/C36000) | 0.8 mm | ≥1.5 mm | The material is soft and thin-walled, making it prone to plastic deformation under clamping force. |
| Engineering plastics (POM/Nylon/PEEK) | 1.0 mm | ≥2.0 mm | High thermal expansion, cutting heat causes warping of thin-walled materials; POM is relatively better. |
The main causes of warping and deformation during CNC machining of thin-walled parts
When machining thin-walled structures on CNC machine tools, operators will encounter three main types of dimensional defects.
| Cutting force sensing | Radial cutting forces push thin-walled material away from the end mill. After the tool passes, the material springs back to its original position. This dynamic change leads to uneven wall thickness, excessive taper, and poor perpendicularity. The resulting vibrations produce chatter marks, commonly known as the “guitar string effect.” |
| Residual stress release | Raw materials such as rolled or extruded billets contain residual stresses in a state of equilibrium. Removing material disrupts this equilibrium, causing the part to warp. This deformation is highly deceptive because it typically occurs after rough machining or when the part is demolded. The part may be dimensionally perfect inside the machine tool, but once demolded, its dimensions may exceed tolerances. |
| Workpiece clamping and clamping stress | The rigid jaws of a standard vise compress thin-walled materials, causing localized deformation. Applying excessive pressure can crush the workpiece, while insufficient pressure can cause it to shift during cutting. Once the clamp is released, the material’s elastic recovery can compromise flatness and perpendicularity tolerances. |
Advanced strategies for CNC machining of parts with minimum wall thickness
working with Elimold frequently inquire about machining thin-walled parts without generating vibration. Manufacturing these parts requires a complete overhaul of standard machining parameters. Therefore, our shop floor operators employ three strategies to control the CNC machining process for parts with the thinnest wall thicknesses.
| Tool selection and geometry | Operators must use short, high-rigidity tools to minimize overhang. Excessive tool overhang multiplies the risk of chatter. Smaller radial cutting depths (typically kept at 10% to 20% of the tool diameter) can significantly reduce lateral loads. Furthermore, conventional milling is preferred to reduce wall loads and minimize heat generated by friction. |
| Optimize toolpath | Traditional serrated toolpaths are strictly prohibited. They generate impact loads and can easily cause thin-walled workpieces to fracture. Instead, cycloidal or helical milling paths are used because they maintain a constant tool engagement angle, eliminating sudden force spikes. Symmetrical machining, i.e., alternating material removal from both sides, maintains balanced cutting forces and prevents unilateral bending. |
| Tooling and Fixture Solutions | Vacuum chucks are an ideal solution for machining thin-walled parts. They distribute clamping force evenly across the part surface, avoiding localized stress concentrations. Custom-designed soft jaws are precision-machined to perfectly conform to the part’s contours, enabling full-contact clamping. In extreme cases, operators may use a sacrificial shim, where an aluminum plate is fixed beneath the thin-walled part during machining and removed in the final step. |
The best material for CNC machining of thin-walled parts
The choice of alloy determines the feasibility of the design. The following is a summary of the Elimold team’s practical experience in CNC machining of thin-walled parts made of various common materials.
| 6061-T6 aluminum alloy | This is the preferred material for CNC thin-wall machining. It features low residual stress, good stability, and high machinability. |
| 075 aluminum alloy | Although it has higher strength, it has enormous internal residual stress. It is extremely prone to deformation, so it should only be used when absolute strength is required. |
| Stainless steel/titanium | These metals experience high cutting forces and poor heat dissipation. They require conservative feed rates and robust fixtures, resulting in significantly higher machining costs. |
| plastic | The required cutting speed and clamping force are much lower. This prevents overheating, melting, and deformation. |
How to reduce the cost of thin-walled CNC machining : A summary of Elimold’s team’s experience
Manufacturing thin-walled CNC parts is inherently costly. High scrap rates, longer machining cycles due to reduced feed rates, and increased initial setup costs due to custom fixtures all contribute to the problem. Adjusting design tolerances can significantly reduce costs. Increasing the wall thickness from 0.5 mm to 0.8 mm can reduce production costs by more than 50%. Relaxing tolerances is also necessary; thin walls cannot maintain the same level of precision as thick walls. If the thickness of a flat profile must be less than 0.5 mm, laser cutting is a more cost-effective option. Designing and sourcing thin-walled precision CNC turning parts requires a tight balance between weight reduction and structural stability. By adhering to a 15:1 height ratio, specifying the use of 6061-T6 aluminum alloy, and allowing a minimum thickness of 0.8 mm, cost reductions and faster production speeds can be ensured.
Common Manufacturing and Design Errors in CNC Machining of Thin-Walled Parts
The following are the most common wall thickness design issues we encounter when reviewing customer drawings.
| mistake | as a result of | Correct approach |
| The aluminum alloy thin-wall design is 0.5mm. | Severe vibration during milling results in surface chatter marks that cannot be eliminated, leading to a scrap rate >30%. | The minimum wall thickness for aluminum alloy is 0.8mm, and 1.5mm or more is recommended. |
| The inner fillet radius is marked R0.5, but the cavity depth is 25mm. | Machining requires a φ1mm tool with an extension of 25mm or more, but severe tool chatter and uncontrollable dimensional changes are present. | For deep cavities, enlarge the bottom angle (R3+), or process in two layers (rough cavity + fine corner clearing). |
| One part used 5 different inner corner radii. | Frequent tool changes result in non-cutting time accounting for over 40% of the total time. | Use a uniform corner radius, with larger corner radii in non-critical areas. |
| The wall thickness abruptly decreased from 3mm to 0.8mm. | Stress concentration combined with sudden changes in cutting force can lead to deformation or fracture in thin-walled areas. | Use beveled edges or large rounded corners for transitions, with thickness variations ≤25%. |
| All external corners must have an outer radius of 2 (R2). | Each outer corner requires a ball end mill to trace an arc, significantly increasing machining time. | Non-surface surfaces should have a standard 0.5mm × 45° chamfer. |
| The bottom surface of the cavity is marked “must be completely flat”. | Adding a corner cleaning process increases costs by 30-50%. | Assess whether a flat bottom surface is a functional requirement. For non-functional surfaces, create an R2 bottom corner. |
| Thin-walled parts do not take clamping deformation into account | The clamping force during processing causes deformation of the thin-walled structure, which springs back after being released, resulting in dimensional deviations. | Design clamping process bosses (to be removed later), or use vacuum chucks/soft jaws. |
| 0.8mm thin-walled stainless steel | Severe work hardening, extremely rapid tool wear, and poor surface quality. | The minimum wall thickness for stainless steel is 1.0mm, and 2.0mm or more is recommended. |
| Chamfering requirements not specified | The factory defaults to a 0.5mm chamfer, but certain mating surfaces should not be chamfered. | Clearly indicate which edges need to be chamfered and which edges do not. |
| 0.8mm thin-walled PEEK plastic | Cutting heat causes localized softening and deformation, resulting in dimensional instability after cooling. | For engineering plastics such as PEEK with a wall thickness ≥1.5mm, pay attention to coolant cooling. |
Obtain thin-walled CNC machined parts through Elimold in just 3 steps
To obtain high-quality thin-walled CNC parts, the right service is essential. Partnering with Elimold ensures optimal results from CNC machining; we are your most reliable thin-walled CNC machining service provider, committed to delivering outstanding results that meet international standards.
Our in-house CNC machining facility is ISO9001:2015 certified, and our thin-wall CNC machining services ensure high-quality parts that meet your specifications. Furthermore, our advanced digital manufacturing platform provides a seamless experience for customers seeking instant quotes for CNC thin-wall parts.
Our in-house manufacturing systems and related processes streamline the design-to-production process, leveraging automation and expertise to ensure every part meets customer specifications. We are proud to offer comprehensive DfM experience, anticipating potential manufacturing challenges and ultimately delivering high-quality results with minimal turnaround time. Now you can begin your thin-wall CNC machining project in just three simple steps:
Upload your technical drawings
The first step is to create detailed technical drawings of the part. This should include all critical dimensions, features, and surface finishes required for the part. Then, you can use CAD software to export the drawings as CAD file formats (STEP, STP, STL, IGES). You can then simply upload the CAD file to our backend to receive a quote.
Get a quick quote within 4 hours
Our rapid quoting capability gives you a detailed price breakdown in minutes. It’s simple, straightforward, and convenient. Instant quotations also come with a free, detailed DFM analysis report to help you improve your part design.
Production begins
Once you review the quote and confirm each design specification, our expert technicians will begin your CNC machining of thin-walled projects, turning your ideas into reality. On our platform, you can track specific production processes to gain a deeper understanding of your production efficiency.
Article Summary
In the article above, Elimold summarizes and introduces design guidelines for CNC machining of thin-walled parts, design principles for different materials, and manufacturing guidelines. You can learn more about the design of thin-walled parts made of different materials and common manufacturing issues.
Finally, we’d like to emphasize that in the design of parts requiring CNC machining, wall thickness is crucial for achieving the proper balance between strength, durability, and manufacturability. You must follow material-specific guidelines to design parts with the minimum wall thickness, and utilize advanced tools and apply proven best practices to obtain high-quality thin-walled CNC parts. For manufacturing requiring excellent wall thickness, contact Elimold’s team of CNC machining experts for thin-walled parts.