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Sheet Metal Fabrication vs. CNC Machining: Which Is Better for Your Custom Part?

Created on 05.21

Meta Description: A clear comparison of sheet metal fabrication and CNC machining to help you choose the right process for your custom part, based on design, material, cost, and performance needs.

Many customers struggle to decide between sheet metal fabrication and CNC machining for their custom parts. Both processes are essential in manufacturing, but they are designed for different part geometries, materials, and applications. Choosing the wrong process can lead to increased costs, delayed projects, and parts that don’t meet your performance requirements. This blog compares sheet metal fabrication and CNC machining, highlighting their key differences, ideal applications, and factors to consider when making your decision.

Key Differences: Sheet Metal Fabrication vs. CNC Machining

Sheet metal fabrication and CNC machining are fundamentally different processes—one shapes flat sheet metal into 3D parts, while the other removes material from a solid block to create complex shapes.

Sheet Metal Fabrication

Sheet metal fabrication involves working with thin, flat sheets of metal (typically 0.5-10mm thick, up to 20mm for heavy-duty applications) to create parts through processes like cutting (laser, plasma, punching), bending, welding, and forming. It’s a “forming” process—no material is removed (except for cutting), and the part retains most of the original material’s thickness, making it lightweight and cost-effective for large parts.

CNC Machining

CNC machining is a “subtractive” process—material is removed from a solid block (billet) using cutting tools (end mills, drills, lathes) to create the desired shape. It’s used for parts with complex geometries, tight tolerances, and solid structures.

When to Choose Sheet Metal Fabrication

Sheet metal fabrication is the better choice for parts that meet the following criteria:

• Flat or Simple 3D Shapes: Parts made from flat sheets bent into shapes (e.g., enclosures, brackets, panels, housings).

• Thin Material: Parts with thickness between 0.5-10mm—sheet metal fabrication is more cost-effective than CNC machining for thin parts; for thicker parts (10-20mm), sheet metal is still viable but may require specialized equipment.

• High-Volume Production: Sheet metal fabrication is fast and cost-effective for high-volume batches (e.g., 100+ parts).

• Lightweight Requirements: Sheet metal parts are lighter than CNC-machined parts (since they use thin material and minimal waste).

• Welded Assemblies: Parts that require welding (e.g., enclosures, frames) are easier to produce with sheet metal fabrication.

Ideal Applications for Sheet Metal Fabrication

Industrial enclosures, electrical panels, brackets, automotive body parts, outdoor furniture, consumer electronics housings, and structural frames.

When to Choose CNC Machining

CNC machining is the better choice for parts that meet the following criteria:

• Complex Geometries: Parts with curved surfaces, deep cavities, intricate details, or non-uniform shapes (e.g., gears, shafts, custom fasteners).

• Tight Tolerances: Parts requiring very tight tolerances (±0.01mm or less)—CNC machining offers higher precision than sheet metal fabrication (typical sheet metal tolerance ±0.1mm, CNC machining ±0.005mm for precision parts).

• Solid Parts: Parts that are solid (not hollow) or require thick, uniform material (e.g., tooling, medical implants, aerospace components).

• Low-Volume or Prototyping: CNC machining is ideal for small batches (1-100 parts) or prototypes, as it requires less setup time than sheet metal fabrication for complex parts.

• Hard Materials: Parts made from hard materials (e.g., titanium, stainless steel) that are difficult to bend or form—CNC machining can cut these materials with precision.

Ideal Applications for CNC Machining

Gears, shafts, custom fasteners, medical implants, aerospace components, tooling, and complex mechanical parts.

Cost and Lead Time Comparison

• Sheet Metal Fabrication: Lower setup costs, faster production for high-volume batches (100+ parts), lower material waste (for simple shapes—typically 5-10% waste vs. 20-30% for CNC machining).

• CNC Machining: Higher setup costs, slower production (due to material removal), higher material waste (from cutting solid blocks—20-30% typical waste)—but more cost-effective for small batches (1-100 parts) or complex parts where sheet metal fabrication is not feasible.

The choice between sheet metal fabrication and CNC machining depends on your part’s design, material, volume, and performance needs. In some cases, a combination of both processes may be ideal (e.g., a sheet metal enclosure with CNC-machined components). Our team can help you evaluate your design and recommend the most cost-effective, efficient process for your custom part.