Overview
Critical dimensions are the features that must meet tolerance for the part to function; reference dimensions are informational values that should not drive inspection the same way. Mixing them without clear marking makes RFQs harder to quote and inspect consistently.
Good RFQs tell the manufacturer where process control and measurement effort must concentrate.
Why the distinction matters
When every number looks equally critical, quoting teams must either over-inspect or ask for clarification. When critical callouts are explicit, process planning can match fixturing, tooling and inspection to the real functional risks.
Reference dimensions still help assembly understanding, but they should remain clearly marked so they are not treated as acceptance criteria by default.
Drawing practice
Use drawing notes or balloons to identify critical-to-function dimensions, GD&T controls and surface finishes that affect sealing, fit or rotation. Keep revision control current and avoid sending unmarked screenshot dimensions as the only authority.
Also list material, quantity or annual volume, and any secondary operations. Incomplete packages are the most common cause of RFQ delays—not machine availability.
Next steps
Use the checklist in our RFQ guidance, then submit files through Request a Quote.
