Oct 12, 2026CNC Machining Guides

How to Prepare a CNC Machining RFQ: Drawing, CAD & Quote Checklist

A practical CNC machining RFQ checklist covering CAD files, drawings, materials, tolerances, quantities, finishes, inspection, packaging, and delivery requirements.

How to Prepare a CNC Machining RFQ: Drawing, CAD & Quote Checklist
A strong CNC machining request for quotation does more than ask for a price. It gives the manufacturer enough information to choose the right process, estimate setup and cycle time, plan inspection, and identify risks before production starts. The clearer the RFQ, the more comparable the quotations you receive—and the less likely the project is to be delayed by assumptions or revision questions.
This guide explains what engineers and procurement teams should include when requesting a quote for custom CNC milled or turned parts.
  1. SEND BOTH A 3D CAD MODEL AND A 2D DRAWING
The 3D model defines the part geometry and helps the supplier plan machining operations, workholding, tool access, and stock size. Native CAD formats such as STEP are generally easier to use for manufacturing than mesh formats. If your assembly contains multiple parts, send each component as a separate file with a clear part number and revision.
The 2D drawing should define requirements that the model alone cannot communicate reliably. These may include tolerances, datums, threads, surface finish, edge breaks, coating areas, inspection notes, and critical-to-function dimensions.
Before sending the RFQ, confirm that the drawing and CAD model show the same revision. A mismatch forces the supplier to stop and ask which file controls.
  1. IDENTIFY THE MATERIAL PRECISELY
Avoid broad descriptions such as “aluminum,” “stainless steel,” or “plastic.” Specify the exact grade and, when relevant, temper or condition—for example, 6061-T6 aluminum or 304 stainless steel. Different grades can vary in machinability, raw-material price, mechanical properties, corrosion resistance, availability, and finishing response.
If an equivalent material is acceptable, say so explicitly and define which performance requirements must remain unchanged. If substitution is not allowed, mark the material as mandatory.
For customer-supplied material, state the stock form, dimensions, quantity, certification requirements, and expected delivery date. Also clarify who carries the risk if the supplied stock contains insufficient machining allowance or hidden defects.
  1. APPLY TOLERANCES ACCORDING TO FUNCTION
A drawing should distinguish critical dimensions from features that can use reasonable general tolerances. Applying a tight tolerance to every dimension increases programming, machining, inspection, and scrap risk without necessarily improving performance.
Use individual tolerances for fits, sealing surfaces, bearing seats, hole patterns, alignment features, and other function-critical geometry. If you use GD&T, identify a stable datum scheme that reflects how the part is assembled or inspected. ASME Y14.5 and ISO 1101 provide established systems for communicating dimensional and geometrical requirements; state which system governs the drawing.
For unspecified dimensions, include a general tolerance note or a referenced standard and class. Never assume that a supplier will interpret an unspecified dimension exactly as you intended.
  1. DEFINE SURFACE FINISH AND EDGE REQUIREMENTS
Surface roughness should be specified only where it affects sealing, friction, fatigue, appearance, coating, or assembly. State the required roughness value and the surfaces to which it applies. A blanket fine-finish requirement can add unnecessary passes and inspection time.
Clarify edge conditions as well. Notes such as “break sharp edges” are useful only when the acceptable edge-break range is understood. Identify edges that must remain sharp, require a controlled chamfer, or must be free from burrs because they contact seals, cables, operators, or mating parts.
  1. DESCRIBE THREADS, INSERTS, AND PURCHASED HARDWARE
For every thread, specify the thread standard, nominal size, pitch, tolerance class, depth, and whether the depth refers to full thread or drilled depth. Note any thread gauges or acceptance criteria required.
If the part includes helicoil-style inserts, press-fit pins, bushings, bearings, or other hardware, state the manufacturer and part number where possible. Clarify whether the CNC supplier should purchase and install the hardware or quote machining only.
  1. STATE FINISHING AND MASKING REQUIREMENTS
Anodizing, passivation, electroless nickel plating, PVD coating, heat treatment, painting, bead blasting, and polishing can affect dimensions, appearance, corrosion resistance, and lead time. Specify the finish standard, type, class, color, texture, and any cosmetic acceptance criteria.
Clearly mark surfaces that must be masked or remain electrically conductive. For dimensionally critical features, indicate whether the stated dimension applies before or after coating. If color matching matters, provide an approved sample or a defined color reference, while recognizing that alloy, surface preparation, and batch conditions can influence appearance.
  1. PROVIDE QUANTITY AND DEMAND INFORMATION
A useful RFQ includes the immediate order quantity and realistic future volumes. Ask for price breaks only at quantities you may actually purchase. Prototype, bridge-production, and repeat-production quantities may require different fixture and process strategies.
If the project may become recurring work, provide an estimated annual usage and expected release pattern. This helps the supplier decide whether dedicated fixtures, custom tooling, or raw-material commitments could reduce long-term cost.
  1. DEFINE INSPECTION AND DOCUMENTATION
List the documents required with the shipment. Depending on the application, this may include a first article inspection report, dimensional report, material certificate, coating certificate, certificate of conformance, inspection records, or traceability data.
Identify critical dimensions and the required sampling level. If a specific measurement method, gauge, CMM routine, or reporting template is required, include it in the RFQ. Inspection requirements added after quotation can change both price and delivery.
  1. EXPLAIN COSMETIC AND PACKAGING EXPECTATIONS
Cosmetic requirements are difficult to price when they are described only as “no scratches.” Define which surfaces are cosmetic, the viewing conditions, acceptable defect limits, and whether a reference sample exists.
Packaging should protect the features that matter. State whether parts require individual wrapping, protective caps, separators, clean bags, custom trays, rust prevention, or special labels. Delicate threads, sealing surfaces, and finished faces may need protection beyond standard bulk packaging.
  1. GIVE A REALISTIC DELIVERY TARGET
State the required delivery date, delivery location, and whether partial shipments are acceptable. Separate manufacturing lead time from shipping time. If the schedule is urgent, explain which date is truly critical and whether the quantity can be split.
Also include the time available for drawing questions, deviation approval, and first article review. A supplier cannot protect the final delivery date if approvals remain open indefinitely.
  1. INCLUDE COMMERCIAL AND COMMUNICATION DETAILS
Provide the buyer or engineer responsible for technical questions, quotation currency, Incoterms if applicable, shipping destination, validity requirements, and any tooling or non-recurring engineering charges that should be separated in the quote.
Ask suppliers to list assumptions and exclusions. This makes quotations easier to compare and exposes differences in material, inspection, finishing, packaging, or delivery scope before a purchase order is issued.
CNC MACHINING RFQ CHECKLIST
Before sending your inquiry, confirm that the package includes:
• Part number and revision • 3D CAD model, preferably a manufacturing-friendly solid format • Controlled 2D drawing • Material grade and condition • Quantity and forecast volumes • Critical dimensions, fits, datums, and tolerances • Surface roughness and edge requirements • Thread and insert specifications • Finishing, color, masking, and post-finish dimensions • Inspection and certification requirements • Cosmetic acceptance criteria • Packaging and labeling instructions • Delivery location and target date • Contact person for technical questions
COMMON RFQ MISTAKES THAT DELAY QUOTATIONS
The most frequent delays come from missing drawings, conflicting revisions, unspecified materials, unclear coating notes, unrealistic tolerance callouts, and quantity information that does not match the expected production method. Another common problem is asking for an urgent quote while leaving the supplier unable to access the CAD files.
A quick internal review before sending the RFQ can prevent days of clarification and produce more accurate, comparable quotations.
REQUEST AN ENGINEERING REVIEW
Zync Precision supports CNC milling, CNC turning, rapid prototyping, low-volume production, inspection, and selected finishing services. Send your CAD files, controlled drawing, material, quantity, tolerance, finish, and delivery requirements through our Request a Quote page. Our engineering team will review the package and identify any missing information before quotation.
For the fastest response, use clear file names and include the part number and revision in your message.