CNC Machining Technical FAQ | YY Precision Expert Answers

Design & Engineering

Q1: What file formats do you accept for quoting and production?
We prefer 3D CAD files in STEP (.stp) or IGES (.igs) format for the most accurate quoting, along with a PDF drawing containing critical dimensions, tolerances, material, and finish specifications. We also accept SolidWorks, CATIA, and other native formats for review.

Q2: How can I reduce the cost of my CNC machined part?
Several design optimizations can significantly reduce cost:

• Increase tolerances where functionally possible.
• Design for standard tool sizes (avoid very small or deep internal radii).
• Consider material machinability (e.g., 6061 aluminum is more economical than 7075 or titanium).
• Simplify geometries to reduce machining time and complex setups.
• Consult our engineers early for a DFM (Design for Manufacturing) analysis.

Q3: What is your standard lead time for prototypes and production?
For standard prototypes, lead time is typically 7-15 working days after design approval. For production runs, lead time depends on volume and complexity, generally ranging from 2-6 weeks. We offer expedited services—contact us for urgent requirements.

Materials & Finishes

Q4: What materials do you most commonly machine?
We specialize in a wide range of metals and plastics, including:

• Aluminum: 6061, 7075, 5052 (excellent for lightweight parts)
• Stainless Steel: 303, 304, 316, 17-4PH
• Steel: Mild steel, 4140, 4340
• Brass & Copper
• Plastics: Delrin (POM), Nylon, PEEK, Ultem

Q5: What surface finishes can you achieve, and how are they measured?
We offer a full range of finishes, from standard as-machined to high-polish: 

• As-Machined: Ra 3.2 μm (125 μin) typical
• Fine Machined: Down to Ra 0.8 μm (32 μin)
• Polished: Mirror finishes (Ra <0.1 μm / 4 μin)
  All finishes are verified using digital surface roughness testers, with reports available upon request.

Q6: What are the main differences between anodizing Type II and Type III?

1. Type II (Sulfuric Acid Anodizing): Provides good corrosion resistance and can be dyed in various colors. Typical thickness: 5-25 μm.
2. Type III (Hard Anodizing): Creates a much thicker, harder, and more wear-resistant coating. It is not easily dyed (typically gray, black, or dark green). Typical thickness: 25-75 μm.

Quality & Tolerances

Q7: What standard machining tolerances can you hold?
Our standard machining tolerances are:

• Milling: ±0.05 mm (±0.002")
• Turning: ±0.025 mm (±0.001")

For tighter tolerances, we routinely achieve ±0.005 mm (±0.0002") and better for critical features, supported by our advanced metrology equipment.

Q8: How do you ensure part quality and traceability?
We operate under a certified ISO 9001:2015 & IATF 16949 quality system. Every order includes:

1. Material Certification (Mill Certs)
2. First Article Inspection (FAI) Report per AS9102 or customer format
3. Full Dimensional Inspection Report with CMM data for critical features
4. Lot Traceability from raw material to shipment

Q9: Do you perform First Article Inspection (FAI) on all orders?
Yes, a complete FAI is performed on the first piece of every new part number or after significant process changes. For production runs, we follow AQL sampling plans while performing 100% inspection on critical characteristics.