Frequently Asked Questions: Custom CNC Parts

1. What materials can be used for custom CNC machining?

CNC machining supports a wide variety of materials to suit different applications. Common options include:

• Metals: Aluminum, stainless steel, brass, copper, titanium, carbon steel, and alloy steels
• Plastics: ABS, PEEK, Delrin (POM), nylon, polycarbonate, PTFE, and PVC
• Specialty materials: Inconel, magnesium, and certain composites

The best material depends on your part’s intended use, mechanical requirements, environmental conditions, and budget.

2. What tolerances can be achieved with custom CNC parts?

Standard CNC machining typically achieves tolerances of ±0.005″ (±0.127mm). For more precise applications, tighter tolerances of ±0.001″ (±0.025mm) or even better can be achieved with high-precision equipment. Tolerance requirements should be clearly specified on technical drawings, as tighter tolerances generally increase production costs and lead times.

3. What file formats are required to get a quote for custom CNC parts?

Most CNC manufacturers accept the following file formats:

• 3D CAD files: STEP (.stp), IGES (.igs), Parasolid (.x_t), SolidWorks (.sldprt)
• 2D drawings: PDF or DWG (especially for tolerance, threading, and surface finish specifications)

Providing both a 3D model and a 2D drawing ensures accurate quoting and production, especially for parts with critical features.

4. What is the typical lead time for custom CNC parts?

Lead times vary based on part complexity, quantity, material availability, and surface finishing requirements:

• Prototypes/small batches: 3–7 business days
• Medium production runs: 1–3 weeks
• Large or complex orders: 3–6 weeks

Expedited services are often available for urgent projects, though they may incur additional fees.

5. What surface finishes are available for custom CNC parts?

A variety of surface finishes can enhance both function and appearance:

• As-machined (standard finish with visible tool marks)
• Bead blasting (matte, uniform texture)
• Anodizing (Type II or Type III for aluminum)
• Powder coating (durable, colored finish)
• Electroplating (nickel, zinc, chrome)
• Polishing (smooth, mirror-like finish)
• Black oxide, passivation, and brushing

The right finish depends on aesthetic preferences, corrosion resistance, and wear requirements.

6. Is there a minimum order quantity (MOQ) for custom CNC parts?

Most CNC machining services have no minimum order quantity, making it ideal for prototypes, one-off custom parts, and low-volume production. However, per-unit pricing typically decreases significantly with higher quantities due to setup cost amortization. For large production runs, manufacturers may offer volume discounts or recommend alternative manufacturing methods if more cost-effective.