What Drawings and Specification Information to Prepare Before Requesting a Quote
When requesting a quote from a CNC machining supplier, providing complete drawings and specification information leads to more accurate pricing and a shorter evaluation cycle. It is recommended to provide at least 2D engineering drawings, 3D files (STEP or IGES), material, order quantity, critical dimensional tolerances, and surface finish requirements. If information is missing, the supplier can only respond with "to be confirmed based on actual specifications," which may lead to price discrepancies or rework risks later.
Drawings: Both 2D and 3D Are Essential
2D engineering drawings are used to annotate dimensions, tolerances, and surface symbols, and serve as the basis for the supplier to determine manufacturing processes and inspection methods. 3D files allow the supplier to directly evaluate geometric complexity and tool paths. It is recommended to provide both STEP and IGES formats, avoiding native CAD files to prevent version incompatibility. If the part has internal features or thin walls, the 3D file is especially important because 2D drawings cannot fully represent them.
Required Specification Items for Quotation
Material and Material Specifications
Clearly indicate the alloy grade (e.g., 6061, 304, 12L14), avoiding vague terms like "aluminum" or "stainless steel" that can cause quotation errors.
Order Quantity and Estimated Annual Usage
Prototype quantities and mass production quantities affect process selection and unit price. Please specify the order quantity per batch and the estimated annual volume.
Critical Dimensional Tolerances
Indicate general tolerances and special tolerances (e.g., ±0.01 mm). Tighter tolerances increase cost and process constraints.
Surface Treatment and Post-Processing
For processes such as anodizing, sandblasting, painting, polishing, or heat treatment, specify the treatment type and applicable areas.
Lead Time and Destination
Provide the expected delivery date and shipping country, as these affect packaging methods and transportation arrangements.
What Happens When Information Is Missing
When material, tolerances, or post-processing are not specified, the supplier typically responds with "to be confirmed based on actual specifications," and the quotation is for reference only. In such cases, unit prices may be adjusted when specifications are confirmed later, potentially leading to inaccurate procurement decisions. It is recommended to provide complete information at the RFQ stage, and if necessary, ask the supplier to review the drawings to ensure both parties have a consistent understanding of the specifications.
Ready with Your Drawings?
Provide your 2D and 3D drawings along with specification information to speed up the quotation and process evaluation.