In CNC machining manufacturing, pricing can vary widely depending on the complexity of the part being produced. But how exactly does complexity influence the final cost? Does the cost also depend on design intricacies, machining time, specialized processes, and the use of CNC 5 axis machining?

Part complexity plays a crucial role in CNC machining pricing. More intricate designs require advanced machinery, longer production times, skilled labor, and specialized tools, all driving up the price. The more complex the part, the more resources are needed, leading to higher overall costs.

Keep reading to learn more about the impact of CNC machining complexity in pricing. We will also discuss some strategies for simplifying intricate part designs and how to achieve the balance between product complexity and the production expenses. 

How Complexity Affects CNC Machining Costs 

The complexity of a part’s design is one of the biggest factors influencing the cost of CNC machining. As parts become more intricate, you need more time, resources, and advanced machinery for them, which increases the expenses. 

For example, simple shapes like a basic shaft may take only an hour to machine. On the other hand, a complex component, like landing gear parts or engine mounts, could take up to 10 hours to complete. The time spent on machining isn’t just about cutting the material; it includes the setup, multiple passes, and possibly even additional inspections.

Certain features in part design can also drive up the cost. These include:

• Sharp internal corners that require extra care and specialized tools.
• Deep cavities that demand more time and effort to machine properly.
• Non-standard hole sizes that might need custom tools or additional setups.
• Specific tolerances or surface finishes, which require more passes and precision work.

Parts with these features often need multiple tool changes or setups to achieve the desired results, which adds both time and cost to the project.

Machining large parts also requires more money. It’s because bigger pieces require more raw material, which adds to the material cost, and machining them requires more time and labor. Increased part size also adds to the complexity of handling and clamping the workpiece. 

Another impact of CNC machining complexity in pricing is the type of machine used. For example, running a 3 axis CNC milling machine typically costs between $20 to $30 per hour. But for more complex parts that require multi-axis machines with rotational capabilities, the cost can rise to $40 or $50 per hour. These 5-axis machines allow for more customization, cutting down on the need for multiple setups, but their advanced functions come at a premium.

Defining Complexity in CNC Machining 

To understand the impact of complexity in CNC machining, you have to understand what complexity is. In simple terms, complexity refers to how intricate or challenging a part’s design is to manufacture. It goes beyond just the component’s shape, but includes everything from the geometry and tolerances to the types of materials used. 

Several factors contribute to the complexity of a CNC part, making it harder to machine and, therefore, more expensive. Let’s break down these factors to understand what makes a part “complex.”

1. Intricate Geometries and Features

When a part has complex shapes or detailed features, it requires advanced CNC machining techniques. For example, curved surfaces or parts with tiny, precise details may need specialized tools and multi-axis machining to achieve the desired outcome. 

CNC machines with more cutting axes can handle these complex geometries more effectively. While a 3 axis CNC machine is great for simpler designs, a 5-axis machine can do more precise cuts with fewer setups, which speeds up the manufacturing process for complex parts. 

Zintilon CNC service can be a good option if you’re looking for complex CNC parts with accurate dimensions. 

2. Tight Tolerances and High Precision

Tight tolerances mean that the part must be manufactured with minimal deviation from its exact specifications. Achieving these high standards is challenging and often requires advanced tools, multiple machining steps, and thorough inspections. 

The more precise the part needs to be, the more time and resources it will take to achieve the desired results. This directly impacts the overall cost of the project.

3. Surface Finishing and Tolerances

Complex parts often require specific surface finishes, such as a smooth texture or uniform roughness. Achieving these finishes, especially on intricate designs, takes time and precision. This level of detail adds another layer of complexity to the manufacturing process. 

Parts that need extremely tight tolerances, such as those used in aerospace or medical applications, are also more difficult to produce and require additional machining steps to meet quality standards. 

4. Multi-Material Compositions

Some parts are made from multiple materials, each with its own unique properties. This introduces complexity because different materials may require different machining techniques. For example, one material might need high-speed cutting while another requires slower, more controlled processing. Combining these materials effectively adds another layer of difficulty to the manufacturing process.

5. Work Holding

The way a workpiece is held during machining is important for achieving precision, especially for complex designs. If it’s not held firmly, it can shift during the cutting process, leading to errors and increased production time. 

High-quality fixtures and jigs are essential for maintaining part accuracy. For complex parts, you often need customized workholding solutions, which increase production expenses. 

Strategies to Simplify Complex Designs

There is a big impact of CNC machining complexity in pricing. However, there are ways to simplify the designs for faster production and lower costs. 

1. Apply Design for Manufacturability (DFM)

Design for Manufacturability (DFM) focuses on creating parts that are easier to manufacture, cost-effective, and less prone to production errors. It optimizes dimensions and tolerances to create more straightforward designs. These parts still meet functional requirements but are easier to machine. 

For implementing DFM, you can:

• Use Standard Sizes: In this practice, designers also use standard sizes for holes, threads, and other features. Custom features often require special tooling, which increases costs and complexity. 
• Add Radii to Sharp Corners: Sharp inner vertical edges increase machining time and tool wear. By adding a small radius (less than a third of the depth), you can reduce machining complexity.
• Limit Cavity Depths: Deep cavities are costly to machine because they require more material removal, which takes longer. To avoid special tooling and minimize production time, keep cavity depths to a maximum of four times the diameter of the cutting tool.

2. Optimize Wall Thickness and Feature Depth

Thin walls may seem like an effective way to reduce material use and weight, but they are challenging to machine. Thin sections can deform, and machining them requires more passes at low cutting depths, increasing the time and difficulty. And thin walls are more susceptible to vibrations, which can reduce accuracy and increase costs.

Designing parts with the right wall thickness and feature depths can make a significant difference in both ease of machining and the final part’s durability.

• Wall Thickness: Ensure that walls are thick enough to withstand machining forces without deflecting. For metals, a minimum wall thickness of 0.8 mm is recommended, while plastics should be at least 1.5 mm thick.
• Feature Depth: Limit the depth of cavities or holes to a 3:1 depth-to-width ratio. This helps improve access for the tools and allows for better chip clearance, reducing the risk of material build-up and improving the overall machining efficiency. 

3. Apply Appropriate Tolerances

Tight tolerances can improve the quality and performance of parts, but they are also difficult to machine. So, to keep the designs simple, you can define tolerances only when absolutely necessary.

Unless your part requires very tight specifications, using the default tolerance (±0.125mm) will suffice for most parts. Tight tolerances should be limited to critical features, such as those requiring high precision for function.

Geometric Dimensioning and Tolerancing (GD&T) offers a way to specify a looser tolerance range for non-critical features while still maintaining part quality. This method can help reduce costs, though it requires advanced design knowledge.

4. Minimize the Use of Text in Design

In CNC machining, intricate text or engravings can add significant complexity. While these features may be necessary for some parts, it’s often more efficient and cost-effective to avoid them altogether.

Instead of engraving text on parts, consider other methods like painting or screen printing, which can be quicker and less expensive than machining detailed lettering.

Balancing Complexity with Cost

To reduce the impact of CNC machining complexity in pricing, you must balance the complexity of a design with manageable costs. The more complex a part is, the more resources, time, and effort it will take to machine. 

Here are some tips for balancing CNC part complexity with cost: 

1. Choose the Right Material

Material selection plays a big role in the part complexity and machining cost. Some materials are easier to machine than others, which can save both time and money.

Materials that are easier to cut, like aluminum, reduce the wear on tools and allow for faster machining. On the other hand, harder materials like stainless steel may require more time and effort to machine, making the process more costly. 

2. Use Standard Features and Sizes

One of the most straightforward ways to reduce CNC machining costs is by simplifying the design’s geometry. Intricate and unconventional shapes increase the time it takes to cut, often requiring specialized tools and multiple setups. Instead, choose simpler shapes that still meet your design goals but are easier and quicker to machine.

Another way to keep costs down is by using standard, off-the-shelf features and sizes. Non-standard designs often require custom tools, extra machining steps, and more time to fabricate, all of which drive up costs.

So, use common hole diameters whenever possible. Custom hole sizes require extra tooling and longer machining time, which increases cost.

And incorporating long threads may seem like a good idea, but they often require special tooling and slow machining processes. Threads longer than 1.5 times the diameter of the hole don’t provide additional strength, so you should avoid them unless necessary. 

3. Utilize Advanced Machining Techniques

Advanced machining methods can help simplify the creation of complex parts by allowing for more efficient production processes.

The 5-axis CNC technique allows for machining complex shapes in a single setup, eliminating the need for multiple fixtures and part repositioning. This not only saves time but also enhances precision. 

Parts with intricate features, like turbine blades or parts with multiple angles, can be made with fewer errors and in less time when using 5-axis machines.

4. Optimize Tool Paths and Machining Strategies

A significant portion of machining cost comes from the time spent running the CNC machine. Poorly optimized tool paths can lead to wasted time, extra movements, and unnecessary tool wear. By planning efficient tool paths, you can reduce machining time and improve precision.

Using specialized software to calculate the most efficient path for each tool can reduce unnecessary movements.

5. Leverage CAD/CAM Software

Modern CAD/CAM software can be a game-changer for simplifying complex CNC designs. These tools offer several ways to optimize the design and machining process.

• Automated Feature Recognition: Advanced software can automatically identify features that need to be machined and optimize them for easier processing. This can reduce the amount of manual input required and speed up the programming phase.
• Simulation and Testing: CAD software allows designers to simulate machining operations before actual production begins. This helps identify potential problems early in the design process, allowing corrections to be made before any time or money is spent on physical production.

Conclusion

There is a huge impact of CNC machining complexity in pricing. Intricate designs require more time, advanced tools, and skilled labor, which add to the production costs. You can make informed decisions about ensuring a balance between part complexity and manufacturing expenses if you have a good understanding of how factors like geometry, tolerances, and materials influence costs. 

Looking for custom precision parts or prototypes? Zintilon offers expert CNC machining services for different industries. Let us help simplify your designs and lower costs without compromising on quality. Reach out for your next project. 

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