Selecting the optimal manufacturing process is critical for the success of any low-volume production run. Two prevalent methods for metal parts are low-volume machining​ (like CNC) and metal extrusion. While both create durable components, their principles, strengths, and ideal applications differ significantly. This guide compares them to help you make an informed choice.

• Low-Volume CNC Machining:​ A subtractive​ process. It starts with a solid block of material (bar, plate, or billet), and material is selectively removed via cutting tools to achieve the final shape. It is digitally driven from a 3D CAD model, offering extreme flexibility in geometry.
• Metal Extrusion:​ A forming​ process. A heated metal billet (usually aluminum) is forced through a shaped die, creating a continuous profile with a fixed cross-section. This profile is then cut to length. The initial die creation is required.

• Machining Winner.​ CNC machining offers near-unlimited geometric freedom. It can produce complex 3D shapes, intricate contours, undercuts, and precise internal features with tight tolerances (±0.025mm or better). Design changes are simply software updates.
• Extrusion Limitation.​ Extrusion is ideal for parts with a constant 2D cross-section​ along their length (e.g., channels, rails, tracks, trim). While the profile itself can be somewhat complex, it cannot create enclosed cavities or vary in the third dimension without secondary operations.

• Machining Winner for Prototypes/First Articles.​ For runs of 1-100 parts, machining typically has a faster initial lead time. Production can start immediately from digital files without tooling. Lead times are often days to a couple of weeks.
• Extrusion Requires Initial Tooling.​ The custom die for extrusion requires design, manufacture, and try-out, adding upfront time (weeks) and cost. This makes it less agile for single prototypes but becomes efficient once the die is made.

• Machining:​ Lower upfront costs, but higher per-part cost. Material waste (chips) and machine time make the cost per part relatively stable, favoring very low quantities.
• Extrusion:​ High upfront cost for the custom die. However, once the die is paid for, the per-part cost drops dramatically due to the rapid continuous nature of the process. It becomes economical at moderate volumes where the die cost is amortized.

• Machining:​ Vastly broader. Almost all engineering metals are available: aluminum, steel, stainless steel, titanium, brass, copper, and exotic alloys. Material properties are those of the solid stock.
• Extrusion:​ Primarily for non-ferrous metals with high malleability. Aluminum alloys are dominant​ (over 80% of extrusions). Some softer copper alloys and magnesium are also extruded. The process can work-harden the material slightly.

• Machining:​ Delivers superior surface finishes directly from the machine (if needed) and excels at holding extremely tight tolerances on all dimensions.
• Extrusion:​ Provides a good, consistent surface from the die but with larger standard tolerances. For precise dimensions, extruded profiles often require secondary machining operations (e.g., drilling holes, cutting slots, milling ends).

• Producing prototypes, bridge production, or parts (1-500 pcs).
• The design is complex, 3D, and requires very tight tolerances.
• Lead time for first parts is critical.
• You require materials other than aluminum (e.g., steel, titanium).
• Design iterations are anticipated.

• The part has a uniform, continuous cross-section.
• Annual or total project volumes are moderate to high (e.g., thousands of meters).
• The primary material is aluminum, prioritizing lightweight strength and good thermal/electrical conductivity.
• You can absorb the upfront die cost and lead time for long-term per-part savings.
• The part benefits from the continuous nature of the process (e.g., trim, frames, heat sinks).