What's the Difference Between Sheet Metal Fabrication and CNC Machining?

一、Process Essence: Forming vs. Cutting

Sheet metal fabrication uses thin metal sheets (typically 0.5–6mm thick) as raw material. It achieves part shaping through non-cutting methods such as shearing, punching, bending, and welding, with its core principle being “forming.” Its advantages include high efficiency, low cost, and suitability for mass-producing structural components like cabinets, enclosures, and brackets.

CNC machining, however, is a subtractive manufacturing process. It employs high-precision machine tools to perform three-dimensional cutting on metal blocks, bars, or thick plates, achieving complex geometries by removing material. Emphasizing “precision” and “complexity,” it is widely used in aerospace, medical devices, precision instruments, and other fields.

二、Mainstream CNC Machining Service Types

CNC Milling is the most widely applied CNC process, capable of machining flat surfaces, curved surfaces, slots, holes, threads, and other features. Five-axis simultaneous milling enables multi-angle machining with a single setup, significantly boosting efficiency and consistency. High-precision milling services achieve tolerances as tight as ±0.005mm, meeting stringent assembly requirements.

CNC Turning focuses on rotary parts like shafts, sleeves, and flanges. Combined with automatic tool change and composite machining capabilities, it enables integrated “turning-milling-drilling” operations, enhancing overall part precision.

三、Key Stages in Sheet Metal Manufacturing: Cutting and Forming

The initial step in sheet metal processing is typically blanking, where Sheet Metal Laser Cutting has become the industry standard. This process employs high-energy laser beams to precisely cut materials like stainless steel, carbon steel, and aluminum. Its advantages include narrow kerf width, minimal thermal deformation, and no tooling requirements, making it particularly suitable for complex contours and flexible small-batch production.

Subsequent bending is performed using CNC bending machines. Precision Sheet Metal Bending, for instance, controls angular deviation within ±0.5°. For soft metals like aluminum, specialized springback compensation strategies must be optimized to ensure dimensional stability.

四、Welding and Surface Treatment Ensure Structural Integrity

Multiple sheet metal components are often assembled into integrated structures via welding. TIG, MIG, and laser welding technologies are flexibly selected based on material properties and strength requirements, with Stainless Steel Welding demanding exceptionally high standards for oxidation resistance and weld aesthetics. Additionally, post-treatment processes like spraying, electrophoresis, and anodizing further enhance product corrosion resistance and surface quality.

五、Casting as a Complement: Addressing Extremely Complex Structures

For components with intricate internal geometries unfeasible via machining or sheet metal fabrication, casting remains an efficient solution. Aluminum Die Casting, valued for its high productivity, excellent density, and superior mechanical properties, is widely used in motor housings, automotive brackets, and communication base station components. Supported by precision die Casting Mold design and mold flow analysis, die-cast parts achieve near-net-shape, significantly reducing subsequent machining requirements.

六、Convergence Trend: Multi-Process Collaboration as Mainstream

Advanced manufacturing now transcends single-process limitations. Typical approaches include Laser Cutting for blanking, CNC milling for critical mounting surfaces, followed by die casting or welding to integrate the entire structure. This “sheet metal + CNC + casting” hybrid manufacturing pathway optimizes costs and delivery cycles while maintaining performance, emerging as the new standard in high-end equipment manufacturing.