Plastic CNC Machining Cost: 8 Key Factors That Affect Pricing

CNC machining is one of the most precise ways to produce plastic parts, but the cost can vary widely depending on several factors. Below are the main elements that influence the total price of plastic CNC machining.

Part Design Complexity

Parts with complex geometry, deep pockets, or thin walls require longer machining time and more precise setups. Simpler shapes reduce tool movement and setup effort.

Geometry: Complex 3D shapes, deep pockets, thin walls, or undercuts require longer machining time.
Tolerances: Tight tolerances need slower feeds, specialized tools, and more inspection.
Number of Features: More holes, slots, or threads increase tool changes and machining steps.
Setup Orientation: Parts needing multiple reorientations raise setup time and fixturing cost.

Material Choice

Different plastics have different machining properties. Engineering plastics like PEEK or Ultem are more expensive and harder to machine than ABS or acetal. Material hardness, stability, and chip behavior all affect machining speed and tool wear.

Machinability: Materials with poor machinability need slower speeds and special tooling.
Stock Size & Shape: Custom or oversized stock wastes material and adds cost.

Machining Time

The time the machine spends cutting the part is a major cost factor. Longer toolpaths, slow feed rates, and frequent tool changes increase machining time and total cost.

Cutting Speed and Feed Rate: Slower cutting increases machine time.
Tool Changes: Frequent tool changes add non-cutting time.
Setup Time: Each setup for a new orientation or fixture costs labor and downtime.
Programming Time: Complex parts require longer CNC programming and CAM optimization.

Tooling and Fixtures

Special tools or fixtures may be needed to hold soft plastic securely or to prevent deformation during cutting. Each additional setup or custom fixture adds cost to production.

Custom Fixtures: Complex parts may need special jigs or holding devices.
Tool Wear and Replacement: Hard materials and tight tolerances increase tool consumption.
Toolpath Optimization: Inefficient tool paths waste time and cause tool wear.

Labor and Overhead

Operator Skill: Highly skilled operators cost more, especially for precision or multi-axis work.
Machine Type: 5-axis or Swiss-type CNCs are more expensive to run than 3-axis mills.
Setup and Inspection Labor: Manual measurement or frequent part checks increase cost.
Maintenance and Energy: Machine depreciation, electricity, and shop overhead all factor in.

Finishing and Post-Processing

Plastic parts often need deburring, polishing, or vapor smoothing to achieve the required surface finish. Additional finishing or assembly steps increase overall cost.

Surface Finish Requirements: Polishing, anodizing, coating, or plating add cost.
Heat Treatment: Adds steps and requires subcontracting or in-house equipment.
Cleaning and Deburring: Manual post-machining work raises labor cost.

Quantity and Production Volume

Smaller batches carry a higher cost per part because programming and setup time are spread across fewer units. Larger runs reduce the cost per piece through efficiency and repeatability.

Batch Size: Small runs have higher per-part cost due to setup time.
Repeat Orders: Larger or recurring jobs spread setup and programming costs over many parts.
Automation Level: Automated production lines or pallet changers lower cost per unit.