The short answer
Choosing **Type II** versus **Type III** anodize is not only a finish comparison—it changes **CNC RFQ cost drivers**, masking labor, dimensional growth assumptions, thread strategy, and whether a preliminary band stays automatic under **rates.v1.1** estimate logic. This guide focuses on **quote and DFM impact**, not a redo of the general Type II vs Type III finish article ([anodizing Type II vs Type III](https://3dwk.com/resources/anodizing-type-ii-vs-type-iii)).
**Example part** illustrations only—no customer cases or invented shop rates beyond planning estimates.
What the quote engine “hears” when you pick a finish
On [quote-new.php](https://3dwk.com/quote-new.php), finish selections add process building blocks (batch minimums, per-part steps, masking risk) on top of material and CNC time. Vague “anodize TBD” keeps cosmetics out of the automatic story; a hard Type III callout with dye, masking maps, and post-machine criticals can widen the band or push **needs_manual** when notes are incomplete. Related: [chem film vs Type II](https://3dwk.com/resources/chem-film-vs-type-ii-anodize-aluminum), [CNC cost drivers](https://3dwk.com/resources/cnc-machining-cost-drivers-buyer-guide), [reading preliminary quotes](https://3dwk.com/resources/reading-preliminary-online-quote-min-mid-max).
Type II vs Type III as RFQ cost levers
**Type II (sulfuric):** common clear or dyed cosmetics and corrosion help on aluminum prototypes. Usually lighter thickness / growth story than hardcoat—still call class/color if you care.
**Type III (hard anodize):** wear surfaces, abrasion narratives, thicker coatings, more growth into tolerances, more masking drama on threads and ground datums. Expect more inspection conversation and often higher finish line contribution than Type II on the same **Example part**.
Neither type is “free” in estimate logic; both can be correct. Over-specifying Type III on a non-wearing cosmetic cover is a frequent prototype cost leak.
Dimensional growth and CNC sequence (quote-relevant)
Roughly half outward / half inward growth is the buyer rule of thumb taught in finish guides—here the RFQ implication matters: if a ØH7 bore must stay H7 after coat, you either mask, machine after anodize, or size pre-coat intentionally. Each choice changes CNC time and finish routing. Leaving “anodize all over, hold all dims” without sequence notes is how automatic bands lose confidence.
Illustration 1 shows an **Example part** RFQ decision: Type II cosmetic path vs Type III wear path and where masking / post-machine notes attach.
Threads, inserts and masking cost
Tapped holes after hardcoat are a classic friction point. Buyers who want Type III on outer wear faces but clean threads should call masking or post-anodize tap/chase explicitly. Inserts in aluminum bosses sometimes simplify the story—state if allowed. Masking maps that cover half the part can dominate finish labor more than the bath type name.
How rates.v1.1 framing interacts (estimates)
CNC aluminum time stays near baseline coefficients; finish adders stack afterward. Alloy planning examples elsewhere on the site (PA66, 17-4PH, IN718/IN625, CoCr powders) remind buyers that **material** and **finish** are separate levers—do not blame “anodize” for a hot-alloy time coefficient. Line totals that exceed configured thresholds still auto-route to **needs_manual** regardless of finish elegance. Treat blog figures as education; your file parse drives the live UI.
DFM notes that shrink the anodize-related band
- Separate cosmetic faces from sealing / bearing faces on the PDF
- Call Type II Class 1/2 or Type III thickness range only where needed
- State mask vs after-machine for critical fits
- Avoid dyeing + hardcoat experiments on the same first article unless required
- Align surface roughness callouts with what anodize can actually deliver ([Ra guide](https://3dwk.com/resources/surface-roughness-ra-for-machined-parts))
Illustration 2 contrasts a thin finish note (“hard anodize”) versus a quote-ready finish block and the path to auto range vs needs_manual.
Example part scenarios
**Example part A:** 6061 cover, clear Type II, no masking, general tolerances—often stays in automatic planning bands when CAD is clean.
**Example part B:** 7075 wear strip, Type III, dye optional, masked threads, post-coat grind on one face—expect denser DFM notes and possibly engineer confirmation before you treat mid as a PO number.
Neither scenario invents a customer order.
What to do next
Pick the thinnest finish story that meets function, write sequence notes, then upload on [quote-new.php](https://3dwk.com/quote-new.php). Services: [CNC](https://3dwk.com/cnc-machining-service.php), finishes context on [materials](https://3dwk.com/materials.php). For finish science detail, use the linked Type II vs Type III resource; for money and RFQ clarity, stay on this checklist.
Common questions
Does Type III always trigger needs_manual?
No. Complete notes and modest envelopes can still auto-band. Incomplete hardcoat + tight fits after coat is the risky combo.
Can I change Type II to Type III after seeing the mid?
Treat it as a new finish interpretation—re-quote rather than mentally scaling mid by a guess factor.
Is chem film cheaper for prototypes that only need conductivity?
Often chem film is the lighter RFQ choice for contact/conductivity stories—see the chem-film comparison article before defaulting to anodize.
Color, class and inspection as commercial inputs
Dyed Type II Class 2 looks simple in marketing photos; on an RFQ it implies dye lot control and appearance criteria. If your prototype only needs corrosion help, clear Class 1 often keeps the finish story—and the estimate—leaner. Hardcoat thickness ranges tied to wear life should be written as ranges your inspector can measure, not as “max hardcoat.” Incoming inspection expectations belong in notes when they affect scrap risk; otherwise shops assume commercial visual checks.
Revision control when finish changes mid-project
Moving from Type II to Type III after CNC is cut may require remask plans, thread chase, or even a remake if growth ate a fit. Treat finish upgrades like geometry revisions: new quote id, new mid, do not scale the old band by a rule of thumb. Procurement teams that reuse stale mids across finish changes create the same confusion as reusing mids across STEP revisions.