The Ultimate Guide to Reducing CNC Machining Costs

As a CNC custom parts manufacturer, I understand that managing machining costs is a top priority for mechanical designers and developers. CNC machining is essential for creating precise and complex parts, but the expenses can add up quickly.

Based on our extensive experience and production feasibility analyses, we’ve identified key factors that influence these costs. By sharing some strategic design tips, we aim to help you significantly reduce expenses without compromising on quality. In this guide, I’ll share our insights and practical tips to help you achieve cost-effective CNC machining for your projects.

Titanium racing parts suppliers

Understanding CNC Machining Costs

What is CNC Machining?

CNC (Computer Numerical Control) machining is a manufacturing process that uses computerized controls to operate and manipulate machine tools. This technology precisely removes material from a workpiece to create custom parts and designs. It’s widely used for its accuracy, efficiency, and ability to produce complex shapes in various materials like metals, plastics, and composites.

Factors Affecting CNC Machining Costs

  1. Machining Time: The longer it takes to machine a part, the higher the cost. Complex designs and tight tolerances can increase machining time significantly.
  2. Material Costs: The type and amount of material used can greatly affect costs. Metals like titanium are more expensive and harder to machine than aluminum.
  3. Labor Costs: Skilled labor for designing, operating, and post-processing can add to the overall cost.
  4. Machine Costs: The type of CNC machine (e.g., 3-axis vs. multi-axis) impacts the cost. Multi-axis machines are more expensive but necessary for complex parts.
  5. Setup Costs: Initial setup costs for each batch can be high, particularly for small production runs.
  6. Surface Finish Requirements: High-quality finishes require additional processing time and resources.
  7. Part Complexity and Dimensions: More complex and larger parts require more time and material, increasing costs.
  8. Tolerance Requirements: Tighter tolerances necessitate more precise machining and quality control, which can drive up costs.

Lightweight titanium racing components

Tips to Reduce CNC Machining Costs

Design Optimization

  1. Simplify Part Geometry: Simple designs reduce machining time and costs. Avoid unnecessary complexities that don’t add functional value.
  2. Add Radius to Internal Edges: Sharp corners are difficult to machine. Adding radii can reduce machining time and tool wear. For example, a cavity that is 12mm in depth should have a 5mm radius at the corners.
  3. Limit Depth of Cavities: Deep cavities require more time and special tools. Keep cavity depths to a minimum to save costs. Ideally, limit cavity depth to four times the length of the tool diameter.
  4. Increase Wall Thickness: Thin walls can deform and require multiple passes. Thicker walls are easier and cheaper to machine. For metal parts, keep wall thickness above 0.8mm; for plastic parts, above 1.5mm.
  5. Limit Thread Length: Threads longer than necessary add to machining time and cost. Limit thread lengths to three times the hole diameter and add unthreaded length at the bottom of blind holes.
  6. Use Standard Hole Sizes: Custom hole sizes require special tools, increasing costs. Use standard drill sizes to streamline the process.
  7. Avoid Thin Walls and Deep Cavities: Thin walls and deep cavities can be challenging to machine accurately, leading to higher costs due to increased time and potential for part scrappage.
  8. Avoid Adding Text or Logos: Adding text or logos increases machining time. If necessary, use engraved text and ensure it is simple and large enough to be machined efficiently.

Copper electroplating process

Material Selection

Choose Cost-Effective Materials: Select materials that meet your design requirements without over-specifying. Aluminum is a popular choice due to its machinability and cost. For instance, Aluminum 6061 is widely used because it is easy to machine, offers good strength, and is relatively inexpensive. Another example is Aluminum 7075, which provides higher strength and durability, making it suitable for aerospace applications, although it is more costly than 6061.

Optimize Material Usage: Design parts to minimize material waste. Efficient nesting and minimal excess material can reduce costs. For example, ABS plastic is often used in CNC machining for prototypes and parts that do not require high strength. ABS is affordable and machines well, making it a cost-effective choice. Similarly, Nylon 6 is another material that is easy to machine and provides good mechanical properties, suitable for a variety of applications from gears to bushings.

Use Softer Materials When Possible: Softer materials are easier to machine, reducing tool wear and machining time. For example, Brass C360 is known for its excellent machinability, making it a great choice for precision components such as fittings and fasteners. POM (Delrin) is another example of a material that is easy to machine due to its high stiffness and low friction, making it ideal for engineering applications such as bearings and insulators.

By carefully selecting and optimizing materials, you can significantly reduce CNC machining costs while ensuring that the parts meet all functional requirements.

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Machining Efficiency

Use Standard Tools and Sizes: Custom tools and non-standard sizes increase costs. Stick to standard tools and sizes whenever possible.

When machining custom racing parts, sticking to standard tools and sizes is crucial for cost efficiency. Custom tools and non-standard sizes often require special orders and longer lead times, which drive up costs. For instance, designing brake calipers with standard bolt holes and thread sizes ensures that widely available tools can be used, reducing both production time and expenses. This is one reason why racing parts can be more expensive, as precision and performance often demand specific, high-quality materials and configurations.

Minimize Machine Setups: Design parts that require fewer setups. Each setup adds to the time and cost.

Efficient design minimizes the number of machine setups required for each part. For example, if you’re designing a gearbox component for a race car, aim to ensure that all necessary machining operations can be completed in as few setups as possible. Each additional setup increases machining time and the risk of alignment errors, leading to higher costs. This complexity in setup is another factor contributing to the higher costs of racing components, where precision and reliability are paramount.

Avoid Small Features with High Aspect Ratios: Small, tall features are prone to vibrations and inaccuracies, increasing machining time.

Small, tall features are challenging, especially in the high-precision world of racing parts. These features can lead to vibrations during machining, causing inaccuracies and extending machining times. When designing intricate components like suspension brackets or aerodynamic parts, ensure that features are not overly thin and tall. This design approach enhances stability during machining, reduces production time, and improves the overall quality and performance of the racing parts. The need for such meticulous design and machining further explains the premium pricing associated with high-performance racing parts.

Bead Blast for Automotive Parts

Post-Processing

Limit Surface Finishes: High-quality finishes are expensive. Only specify them where necessary. For example, if a part does not require a polished appearance or additional protection, opt for an “as-machined” finish instead of an anodized or powder-coated finish. Anodizing, for instance, provides a durable and corrosion-resistant surface but can add significant cost. Powder coating offers excellent surface protection and aesthetics but is best reserved for parts exposed to harsh environments or requiring a specific appearance.

Avoid Text and Logos: Adding text or logos requires additional machining steps. Use alternative methods like laser etching if needed. For instance, if you need to add a serial number or company logo to a part, laser etching is a cost-effective method that can be done quickly and with high precision. This process is much faster and cheaper than engraving, which requires additional tooling and setup. For example, laser etching a logo onto an aluminum part can take just a few seconds per piece, whereas engraving the same logo might take several minutes.

Batch Production

  1. Leverage Economies of Scale: Larger production runs spread the setup cost over more parts, reducing the cost per part.
  2. Plan for Mass Production: If possible, design for large batches to take advantage of lower unit costs.

Other Tips

Use Multi-Axis Machines Wisely

While multi-axis machines can be more expensive, they offer significant advantages in terms of precision and efficiency. For example, a 5-axis CNC machine can access all sides of a part without needing to reposition it, reducing the number of setups required. This not only saves time but also minimizes the risk of errors that can occur during multiple setups. For instance, complex aerospace components often benefit from 5-axis machining, where precision and accuracy are paramount, and the reduced setup time translates directly into cost savings.

Regular Maintenance

Keeping your machines well-maintained is crucial for efficient operation and cost reduction. Regular maintenance helps prevent unexpected breakdowns, which can halt production and lead to costly repairs. For example, routine checks and timely replacement of worn parts can prevent issues such as spindle failure, which can be expensive to fix and cause significant downtime. By ensuring that your CNC machines are always in top condition, you can maintain a smooth production process and avoid unnecessary expenses.

Surface finishing in CNC machining of 6082 Aluminum Alloy

Choosing the Right CNC Machining Partner

Experience and Expertise

Choosing an experienced CNC machining partner can significantly reduce costs. Experienced partners understand the nuances of the machining process and can offer insights that less experienced providers might miss. They can help optimize designs for manufacturability, suggest cost-effective materials, and ensure high-quality production.

For more details, check out the blog below:

Benefits of Partnering with Experts

  1. Optimized Designs: Expert partners can review your designs and suggest modifications to reduce machining time and material waste.
  2. Material Recommendations: They can recommend materials that provide the necessary properties at a lower cost.
  3. Efficient Production: Experienced partners have streamlined processes that minimize setup times and increase production efficiency.
  4. Quality Assurance: They implement stringent quality control measures to ensure consistent part quality, reducing the need for rework.

Conclusion

Reducing CNC machining costs is achievable by optimizing design, selecting appropriate materials, and leveraging efficient machining practices. By understanding the factors that drive costs and applying these tips, you can significantly lower expenses and improve profitability.

Choosing an experienced CNC machining partner is also a crucial step in reducing costs. Since 2005, our company has provided cost-effective CNC machining services, helping numerous businesses achieve rapid prototyping and production with a focus on quality and efficiency. At Modo Rapid, we are an IATF16949 and ISO9001 certified factory specializing in on-demand manufacturing.

Our services include CNC machining, 5-axis machining, 3D printing, vacuum casting, and injection molding. Contact us today to learn how we can support your manufacturing needs with precision and reliability.