As Machined: Thickness, Specs & Materials

What is As machined?

Tool marks remain visible, and the machined geometry preserves drawing tolerances better than abrasive post-processing.

How it works

The cutting tool itself generates the final surface; abrasive media or grit is not applicable. Feed per tooth, tool nose radius, runout, rigidity, material, coolant, and tool wear set the lay and profile. Ra 1.6–3.2 µm (63–125 µin) is a common commercial result. Common drawing classes are 0.8 µm (32 µin), 1.6 µm (63 µin), 3.2 µm (125 µin), and 6.3 µm (250 µin), measured under ASME B46.1 or ISO 21920.

Why specify it

Lowest secondary-process cost
Common Ra 1.6–3.2 µm (63–125 µin)
Best preservation of machined dimensions
Shortest lead time

Where it falls short

Visible cutter and feed marks remain
Appearance varies by toolpath and setup
Burr removal is still required
Ra alone does not control lay or waviness

As machined at a glance

As machined is a middle-of-the-range finish; its best score is cosmetic quality (20 of 100), at a budget cost. It adds little corrosion protection or lubricity. Surface hardness is not rated: the finish leaves the part's own surface.

Corrosion protectionMinimal0 / 100

Surface hardnessNot rated—

Cosmetic qualityLow20 / 100

LubricityMinimal10 / 100

Relative costBudget0 / 100

Each score is 0–100 against every finish in this catalog. Corrosion comes from salt-spray life (ASTM B117, log scale) and hardness from the finish layer's Vickers or pencil hardness; cosmetic, lubricity and cost are FabDigit's engineering assessment. Economy on the radar is the inverse of cost.

As machined key numbers

Typical values from the governing specifications and shop practice; bars are this finish against the highest value among mechanical finishing finishes.

Thickness0 µm0 mil

Thickness: No coating; typical Ra 1.6–3.2 µm (63–125 µin).
Electrical: Unchanged
Appearance: Visible directional or toolpath-dependent cutter marks.

Specifications for As machined

The documents a drawing cites to define this finish, with the Type / Class rows that apply. Each links to a page explaining the standard.

Drawing call-out

AS MACHINED, Ra 3.2 µm MAX UNLESS OTHERWISE SPECIFIED; REMOVE BURRS AND BREAK SHARP EDGES 0.2–0.4 mm

Which materials take As machined?

Verdict per material family, with the grades that behave differently. Each family links to its datasheets in the material library.

Material family	Verdict	Notes
Aluminum	Yes	Common baseline for CNC aluminum parts.
Brass	Yes	Suitable; protect against smear and media embedment.
Copper Alloy	Yes	Suitable; expect faster cutting and easier smearing than steel.
Polymer	Yes	As-machined plastics are common; tool marks remain visible.
Stainless Steel	Yes	Functional baseline; passivation may follow if required.
Steel	Yes	Requires corrosion protection where service environment demands it.
Titanium	Yes	Suitable with contamination-controlled tooling or media.
Magnesium Alloy	With care	Possible with non-sparking media and fire-safe dust control.
Zinc Alloy	With care	Soft die-cast zinc cuts quickly and can embed media.

How As machined is applied, and what it does to the part

1Machine to final size
2Deburr within stated edge break
3Clean
4Inspect dimensions
5Measure Ra where specified

Dimensions	No secondary abrasive operation changes dimensions; specified machined tolerances survive, subject to normal deburring at edges.
Build-up per side	0 µm — No post-process buildup or removal.
Masking	Rarely needed. No secondary finish is applied.
Electrical	Unchanged
Appearance	Visible directional or toolpath-dependent cutter marks.
Added lead time	0 working days on top of the bare part

Design rules for As machined

What to decide on the drawing before the part goes to the finisher.

Put the Ra symbol on functional faces.A blanket roughness requirement adds avoidable machining cost.
Specify lay where sealing or sliding demands it.Equal Ra values can have different directional behavior.
Define edge break separately.As machined does not mean burrs may remain.
Use 0.8 µm only where needed.Ra 0.8 µm (32 µin) usually needs a fine finishing pass.

As machined versus the alternatives

Finishes engineers weigh against As machined, and when each wins.

Finish	Corrosion	Hardness	Cosmetic	Cost	Choose it when
As machined this page	0	—	20	$	—
Bead Blasting As machined vs Bead Blasting →	5	—	65	$	when tool marks must be visually homogenized
Surface Grinding As machined vs Surface Grinding →	0	—	35	$$$	when tighter flatness and lower Ra are required

As machinedBead Blasting

The radar overlays As machined with Bead Blasting, its most common alternative — chosen when tool marks must be visually homogenized. Scores in the table are 0–100 across every finish in the catalog.

Cost, lead time and compliance

Relative cost

As Machined is a budget-cost finish ($): cheaper than about 100 % of the finishes FabDigit quotes.

Finishing is priced per part with a lot minimum, from FabDigit's own China-side rates. The exact figure appears on the instant quote once the part is uploaded.

Lead time and compliance

Added lead time	0 working days
RoHS	Compliant
Notes	No secondary finishing chemistry or media is used.

What As machined is used for

Functional prototypes
Internal brackets
Precision housings
Machine components

As machined — frequently asked

what Ra is as machined

A common CNC as-machined range is Ra 1.6–3.2 µm (63–125 µin). Capability depends on material, tool geometry, feed, rigidity, and whether the surface is turned, milled, bored, or faced.

what does Ra 0.8 mean

Ra 0.8 µm equals about 32 µin and is a fine machined finish. It often requires a dedicated finishing pass and good tool condition.

what do Ra 1.6 3.2 and 6.3 mean

Ra 1.6 µm is about 63 µin, 3.2 µm is 125 µin, and 6.3 µm is 250 µin. Lower values are smoother, but Ra does not describe lay or waviness.

does as machined include deburring

Production parts should be free of burrs, but the drawing should state an edge-break range such as 0.2–0.4 mm. Broad abrasive blending is not implied.

what tolerances survive bead blasting after machining

As-machined dimensions are least disturbed because there is no secondary abrasion. Bead blasting removes essentially no bulk stock but can alter edge condition and precision surface texture.