Manufacturing Techniques

Additive manufacturing (AM) and subtractive manufacturing (SM) are two fundamental approaches to creating parts and components. Both methods have distinct processes, benefits, and limitations. Here’s a detailed comparison, focusing on CNC (subtractive) and 3D printing (additive):

Additive Manufacturing (3D Printing)

How It Works:
- Additive manufacturing builds parts layer by layer from the ground up. It starts with a digital 3D model, which is sliced into thin layers by the printer’s software. The printer then deposits material layer by layer to create the final object.

Common Technologies:
- What we have access to
  - FDM (Fused Deposition Modeling): Uses a thermoplastic filament extruded through a heated nozzle.
  - SLA (Stereolithography): Uses a laser to cure liquid resin into solid plastic.
- What we don't have access to
  - SLS (Selective Laser Sintering): Uses a laser to sinter powdered material into solid parts.
  - DMLS (Direct Metal Laser Sintering): Uses a laser to sinter powdered metal.

Pros:
- Complex Geometries:
  - Can produce complex shapes and internal structures that are difficult or impossible with subtractive methods.
- Material Efficiency:
  - Minimal waste since material is only used where needed.
- Rapid Prototyping:
  - Quick turnaround from design to part, ideal for prototypes and custom parts.
- Customization:
  - Easily allows for custom and on-demand manufacturing without the need for new tooling.
- Tooling Reduction:
  - No need for custom molds or jigs, reducing upfront costs.

Cons:
- Material Limitations:
  - Limited range of materials compared to subtractive manufacturing, especially in high-performance engineering materials.
- Surface Finish:
  - Parts may require post-processing to achieve desired surface quality and mechanical properties.
- Size Constraints:
  - Limited build volume, especially for desktop 3D printers.
- Mechanical Properties:
  - Parts may not have the same strength and durability as those produced with traditional methods, especially for load-bearing applications.

Learn More About Additive Manufacturing

Subtractive Manufacturing (CNC Machining)

How It Works:
- Subtractive manufacturing removes material from a solid block (workpiece) to create the desired shape. This is done by cutting, drilling, milling, or turning using CNC machines, which are controlled by computer-generated code.

Common Machines:
- What We Have access to:
  - CNC Mills: Use rotary cutters to remove material.
  - CNC Routers: Typically used for cutting softer materials like wood or plastics.
- What we don’t have access to:
  - CNC Lathes: Rotate the workpiece against a cutting tool.
  - CNC Grinders: Use abrasive wheels to remove material and finish surfaces.

Pros:
- Material Variety:
  - Can machine a wide range of materials, including metals, plastics, composites, and ceramics.
- Surface Finish:
  - Produces parts with excellent surface finish and tight tolerances.
- Mechanical Properties:
  - Machined parts typically have superior mechanical properties and strength compared to 3D-printed parts.
- Scalability:
  - Well-suited for mass production with consistent quality.
- Accuracy and Precision:
  - High precision and repeatability, making it ideal for critical components.

Cons:
- Material Waste:
  - Generates a significant amount of waste material, especially when machining from solid blocks.
- Complexity and Cost:
  - Can be expensive and time-consuming to set up, especially for complex geometries requiring multiple setups and specialized tooling.
- Limited Geometries:
  - Some complex internal features or undercuts may be difficult or impossible to machine.
- Tool Wear:
  - Cutting tools wear out over time and need to be replaced, adding to operational costs.

Learn More About Subtractive Manufacturing

Key Comparisons
- Material Usage:
  - Additive:
    - Material is added layer by layer, highly efficient with minimal waste.
  - Subtractive:
    - Material is removed from a larger block; can produce significant waste.
- Design Complexity:
  - Additive:
    - Capable of producing highly complex geometries, including internal structures and overhangs.
  - Subtractive:
    - Limited by the reach and accessibility of cutting tools; complex parts may require multiple setups.
- Surface Finish and Precision:
  - Additive:
    - Often requires post-processing for smooth surfaces and precise dimensions.
  - Subtractive:
    - Typically achieves high surface finish and precision directly from the machining process.
- Material Properties:
  - Additive:
    - Mechanical properties can vary, often lower than those of machined parts; anisotropic properties can be an issue.
  - Subtractive:
    - Generally, produces parts with superior mechanical properties and isotropic strength.
- Speed and Efficiency:
  - Additive:
    - Fast for prototypes and small batches, setup is quick but build times can be long for large parts.
  - Subtractive:
    - Efficient for high-volume production; setup can be time-consuming, but individual parts can be produced quickly once setup is complete.
- Cost:
  - Additive:
    - Lower cost
  - Subtractive:
    - Higher setup and tooling costs