CNC Machining Magnesium AZ31 for Precision Parts

Milled Prismatic Parts

Three-axis milling suits plates, brackets, blocks, and manifolds with accessible planar faces. Confirm tool reach, internal-corner radii, and datum locations before release.

Turned Rotational Parts

Two-axis turning suits bushes, sleeves, rings, and stepped shafts with concentric features. Ask whether thin sections, cross-holes, or interrupted profiles require secondary milling.

Five-Axis Complex Parts

Five-axis machining suits compound angles, blended surfaces, and features requiring multiple tool orientations. Review fixture access and whether critical surfaces can retain stable datums.

Thin-Wall Housings

1 mm-class walls demand a stiffness review because machining forces and clamping can distort open pockets. Define wall thickness, local ribs, and inspection support points on the drawing.

Precision Mold Or Die Components

Two-process routes commonly combine milling with EDM or grinding for deep, sharp, or precision features. Confirm heat-treatment sequence, grinding stock, and mating-component datums.

Prototypes And Low Volumes

One-piece prototypes can validate geometry, assembly clearance, and finish expectations before a larger release. Provide the 2D drawing, 3D model, revision, quantity, and critical dimensions for process review.

Read The Mill Certificate

EN 10204 3.1 or equivalent documentation should identify the exact alloy designation, product form, heat or lot, chemistry, and applicable temper. Confirm the drawing’s material callout against the certificate before releasing stock.

Choose Starting Stock

Billet supports larger milled envelopes; plate suits flat parts but requires attention to thickness and rolling direction. Bar is efficient for turned geometry, while sheet is primarily selected where formed features are required.

Select By Service Conditions

AZ91 generally favors higher strength needs, whereas AZ31 is the more formable magnesium choice; both need corrosion exposure assessed with the intended finish. Aluminum may offer easier availability and corrosion options, but carries a weight penalty.

As-Machined And Deburred

An as-machined surface retains tool marks and offers no added corrosion barrier. Define allowable burr condition, edge-break size, and any functional surfaces that must remain uncoated.

Chemical Conversion Coatings

Chemical conversion treatment provides a thin base for corrosion control and subsequent paint adhesion. Call out the approved process, coverage requirement, and whether threads, bores, or datum faces require masking.

Paint And Powder Coatings

Paint and powder coatings add visible coverage but can build on edges, holes, and sealing faces. State color standard, gloss, coating system, cure limits, and coating-free zones rather than specifying color alone.

Anodic Or PEO Routes

Anodic and plasma-electrolytic approaches require geometry and process compatibility review before release. Identify critical dimensions, cosmetic faces, adhesion testing, and permitted local finish variation in the drawing notes.

Datums And Geometry

Three mutually related datums should locate the part and its critical interfaces. Specify minimum wall areas, internal corner radii, thread class, and allowable burr direction; thin webs and sharp transitions deserve a distortion review before release.

• Identify mating faces and locating features
• Dimension critical features from functional datums
• State thread gaging and edge-break requirements

Inspection Plan

First-article inspection should verify datum setup, critical dimensions, hole position, thread function, flatness, and surface roughness. In-process checks are warranted for thin-wall geometry, features affected by multiple setups, and dimensions following stress-relieving or finishing operations.

• Link each CTQ to a method and frequency
• Define CMM, pin-gage, or thread-gage use
• Record drawing revision and material lot

Traceability And Protection

Each material lot should be traceable to the ordered AZ31 designation and accompanying documentation. Specify clean, dry separation between parts, protected threads and edges, and packaging that prevents rubbing, moisture exposure, and deformation in transit.

• Request material certificate requirements upfront
• Mark lots without damaging functional surfaces
• Approve packaging for delicate thin sections

Chip And Dust Controls

Ask for the written chip-collection, housekeeping, segregation, and emergency-response procedure for magnesium work. A credible supplier explains how chips, fines, coolant compatibility, ignition sources, and disposal are controlled—not merely that it is experienced.

• Ask which records apply to your part number.
• Request the machining-area risk assessment.
• Confirm whether thin-wall features change the control plan.

Material And Machine Evidence

Request the mill certificate and receiving traceability from AZ31 stock to finished parts. Ask which machine configuration, workholding, tool access, and operations are proposed for the drawing; accept capability claims only with project-specific confirmation.

• Material designation and condition
• Lot and heat identification
• Proposed process sequence

DFM Inspection And Communication

Require a drawing-review response that identifies datums, critical features, tolerances, and finish risks before release. Define the inspection method, report format, revision-control contact, finishing handoff, and approval points in the RFQ.

• First-article evidence requested
• Measuring method for each CTQ
• Revision and deviation workflow

Review The Service Environment

AZ31 can corrode when moisture, salts, or incompatible fluids reach an unprotected surface. Define the operating environment, storage conditions, and approved coating system before release.

Control Interfaces And Coatings

Magnesium-to-steel or aluminum interfaces can create galvanic-corrosion risk when an electrolyte is present. Specify isolation, fastener treatment, coating coverage, masking, and coating verification on the drawing.

Dimension What Functions

Nonfunctional tight tolerances increase setup, inspection, and scrap without improving assembly performance. Identify functional datums, critical features, measurement points, and realistic tolerances in the 2D drawing.

Release A Complete Safety Package

Magnesium chips require a documented fire-risk and housekeeping plan appropriate to the process. Provide material grade, model, revision, quantity, finish, heat-treatment requirements, inspection needs, and mating-part context before quotation.

Define Application Requirements

One application brief should identify load path, operating environment, mating parts, annual quantity, and delivery target. Two stakeholders—design engineering and quality—should mark CTQs, functional datums, and acceptance evidence.

Release Controlled Design Data

Two controlled files, a dimensioned drawing and native or neutral 3D model, should carry the same revision. One drawing package should state units, general tolerances, threads, surface requirements, and inspection points.

Close DFM And Commercial Gaps

One DFM response should confirm tool access, workholding, datum sequence, burr treatment, and inspection approach. Two teams—procurement and engineering—should resolve quotation assumptions on material form, finish, quantity, packaging, and lead time.

Approve Articles And Changes

One first-article plan should define sample quantity, report format, measured characteristics, and disposition authority before production. Two change controls—written revision release and supplier impact review—should precede any drawing, material, process, or finish change.