CNC Machining Tolerances Guide: How Tight Is Realistic?

CNC machining tolerances decide whether a part fits, seals, and performs—and how much it costs. Specifying ±0.005 mm everywhere feels safe but quietly multiplies price and scrap. This guide explains what tolerances are actually achievable by process, how GD&T helps you call out only what matters, and how to brief a shop so you pay for precision only where it earns its keep.

What “Tolerance” Really Means

A tolerance is the allowable variation on a dimension. Tighter tolerances need slower feeds, more passes, finer tools, and more inspection. Our CNC milling and CNC turning cells hold standard ±0.05 mm and ±0.01 mm on critical features—but every step tighter carries a cost.

Realistic Tolerances by Process

• As-machined — ±0.05 mm typical, ±0.01 mm on critical features.
• Ground features — surface and cylindrical grinding reach microns.
• Bores and holes — honing and EDM for tight, burr-free geometry.

GD&T: Call Out Only What Matters

Geometric Dimensioning and Tolerancing lets you constrain function—flatness, position, runout—instead of over-tolerancing every size. Good DFM support reviews drawings so tolerance isn’t specified where it doesn’t pay. Our GD&T machined parts guide goes deeper.

Design for Consistent Tolerance

Symmetric datums, generous fillets, and measured callouts keep cost down. We help trade tolerance against cost during DFM support before any metal is cut.

Inspection Is How Tolerance Becomes Real

Precision only counts if measured. First-article inspection, in-process gauging, and CMM reports back every lot. Deburring and passivation finish critical edges and surfaces.

FAQ

What tolerance is realistic as-machined?
±0.05 mm standard, ±0.01 mm on critical features with calibrated equipment.

Should I use GD&T?
Yes—when function depends on form or position, GD&T is clearer and often cheaper.

How do you prove consistency?
CMM and first-article reports per lot.

Why Choose Huaxiao for Tight-Tolerance Work

Our precision machining service combines tight-tolerance CNC, grinding, and inspection so parts ship right. See precision machined parts and stainless machining. Upload your model for a build-ready quote.