MIC-6 Cast Aluminum Tooling Plate
Also: MIC-6, Mic6, Mic 6, cast aluminum tooling plate, cast tool plate, jig plate, precision cast plate, ATP-5 (competing cast plate), K100-S (competing cast plate), ALCA 5 (rolled tooling plate)
MIC-6 is cast aluminum tooling plate: stress-free, flat and finished on both faces, for fixtures, bases and jigs. Low strength; not for cosmetic anodizing.
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At a glance
| Density | 2.8 g/cm³ (0.101 lb/in³) |
|---|---|
| Tensile strength | 166 MPa (24 ksi) |
| Yield strength | 105 MPa (15 ksi) |
| Hardness | 65 HB |
| Elongation | 3% |
| Modulus of elasticity | 71 GPa (10.3 Msi) |
| Thermal | Thermal conductivity ~142 W/m·K; melting range not published separately, roughly 555-640 °C (1030-1185 °F) as for other aluminum casting alloys; keep it well below about 260 °C (500 °F) in service and processing |
| Composition | Proprietary cast aluminum alloy (Arconic), not an Aluminum Association registered composition; confirm the nominal chemistry on the producer data sheet |
Typical values, As supplied: continuous cast, thermally stress-relieved, machined both faces (no wrought temper applies). Confirm against the mill certificate and the purchase spec.
- MachinabilityExcellent
- Machines faster and cleaner than 6061 with short chips and no smearing, and the plate does not move when material is removed, so pockets, grids of tapped holes and vacuum channels come out flat. Fine cast porosity can show on polished surfaces.
- WeldabilityNot recommended
- It can be TIG welded in a pinch, but porosity from the cast structure gives weak, gassy welds and the heat undoes the stress relief and flatness that the plate was bought for. Bolt or dowel assemblies together.
- FormabilityNot recommended
- With about 3% elongation it cracks on any bend; it is a plate to machine, never to form.
- Corrosion resistanceGood
- Fine indoors bare; in a wet shop or with coolant exposure it stains and pits at surface porosity, so protect fixtures with chem film or electroless nickel. Not for marine service.
MIC-6 is a trade name (Arconic, formerly Alcoa) for continuous-cast aluminum plate that is stress-relieved and then machined flat and parallel on both faces to a fine finish. It is bought for what it does not do: it does not warp when you machine a pocket in it, because the cast structure carries almost no residual stress, and it does not need to be fly-cut flat before use, because it arrives at about ±0.13 mm (±0.005") flatness with a 0.5 um (20 uin) Ra surface. That makes it the default for fixture bases, vacuum chucks, CMM plates, jigs, machine bases, index tables and vacuum forming and injection mold plates.
The alloy itself is a proprietary casting composition, not a registered wrought grade, and its strength is low: about 166 MPa (24 ksi) tensile and 105 MPa (15 ksi) yield with only 3% elongation, roughly half of 6061-T6. It machines very fast and cleanly, holds tight tolerances because it does not move, and takes electroless nickel or a protective chem film well. It should not be loaded like a structural part, bent, or fusion welded, and it should not be specified for cosmetic anodizing: the cast structure anodizes grey and blotchy and cannot be colour-matched.
Competing cast tooling plates (ATP-5, K100-S) and rolled tooling plates (ALCA 5, based on 5083) fill the same role with slightly different numbers and finishes; when a drawing says "MIC-6" most shops treat it as a class, and when the exact plate matters, name it on the PO. For a plate that must be both flat and strong, use 6061-T651 or 7075-T7351 and accept a flattening operation.
Heat treatment
Not heat-treatable. The plate is thermally stress-relieved at the producer after casting, which is the whole point of the product. Do not stress-relieve, anneal or heat it in the shop; sustained heating toward 260 °C (500 °F) or higher risks distortion and loses the flatness. Machine it as received.
Tempers and conditions
- As cast and stress-relieved (no temper designation)
Stock forms
- Plate 6.35-100 mm (1/4-4") thick, both faces machined, PVC-coated
- Cut-to-size blanks from distributors
- Cast bar (limited, from competing producers)
Relative cost
Tier 3 of 5. About 1.5-2x the price of 6061-T651 plate per pound, but it arrives flat and finished on both faces, which usually saves more machining time than the premium costs on fixture work.
Typical applications
- Fixture plates, tombstones and vacuum chucks
- Machine bases, sub-plates and index tables
- Inspection and CMM surface plates (light duty)
- Vacuum forming, thermoforming and RTM tooling
- Injection mold plates and prototype mold bases
- Optical benches and instrument baseplates
- Printing, electronics and semiconductor equipment platens
Process compatibility
How MIC-6 takes each process, and what to specify. Each process links to its own guide and to the shops that do it.
| Process | Rating | Notes |
|---|---|---|
| CNC Machining | ExcellentExcellent | Fast, clean and dimensionally stable; the reason to buy it. Arrives flat, so skip the fly-cut and go straight to features. |
| CNC Milling | ExcellentExcellent | Grids of holes, pockets and vacuum channels stay flat; light porosity can appear on fine finishes. |
| CNC Grinding | GoodGood | Grinds and laps well when a fixture plate needs flatness beyond the as-supplied ±0.13 mm (±0.005"); light cuts and coolant. |
| Wire EDM | GoodGood | Cuts cleanly for precision cutouts and gauge features; porosity rarely disturbs the wire. |
| Waterjet Cutting | GoodGood | The usual way to cut blanks and large cutouts from full plates without heat. |
| Electroless Nickel Plating | GoodGood | The common protective and wear finish on MIC-6 fixtures; a zincate pretreatment and a sealed 12-25 um (0.0005-0.001") deposit. |
| Chem Film (Chromate Conversion Coating) | GoodGood | Chromate conversion protects against coolant staining and keeps conductivity; the finish looks mottled on cast plate. |
| Anodizing | PoorPoor | Anodizes for protection only: the cast structure gives a grey, blotchy coating that cannot be colour-matched. Never specify cosmetic or dyed anodize. |
| Hardcoat Anodizing | FairFair | Type III builds unevenly and thinner than on 6061; acceptable for wear on a fixture where appearance is irrelevant, with edges radiused. |
| Welding | Not recommendedNot recommended | Porous, gassy welds, and the heat undoes the stress relief and flatness. Bolt and dowel assemblies together. |
| Press Brake Forming | Not recommendedNot recommended | About 3% elongation; it cracks on any bend. |
| Heat Treating | Not recommendedNot recommended | Not heat-treatable and already stress-relieved; heating in the shop only risks distortion. |
| Laser Cutting | PoorPoor | Plate is usually too thick for a clean laser cut and the heat-affected edge is unwanted on a precision plate; saw or waterjet the blanks. |
Design and sourcing tips
- Specify "cast aluminum tooling plate, MIC-6 or equivalent" unless the exact producer matters; add the flatness and thickness tolerance you need so a substitute is checked against it.
- Do not use it as a structural member or a bent part; its strength is about half of 6061-T6 and its elongation is 3%. Use 6061-T651 for load-carrying plates.
- Leave the as-supplied faces alone where you can; if a datum face must be skimmed, take a light equal cut from both faces to keep the plate balanced.
- Never call out cosmetic or dyed anodize. Specify electroless nickel or chem film for protection, or leave fixture plates bare and oil them.
- Keep the plate away from heat: no welding, no stress relief, no hot processes; the flatness lives in the stress-relieved cast structure.
- Order oversize by 3 mm (1/8") on length and width and have the shop square the edges; the faces are finished, the edges are saw cut.
Frequently asked questions
- What is MIC-6 aluminum?
- MIC-6 is a brand of cast aluminum tooling plate from Arconic. The plate is continuous cast, stress-relieved, then machined flat and parallel on both faces to about ±0.13 mm (±0.005") with a 0.5 um (20 uin) Ra finish. It is bought for fixtures, bases and tooling that must stay flat after machining, not for its strength, which is about half of 6061-T6.
- What is the difference between MIC-6 and 6061 aluminum?
- 6061-T651 is a wrought, heat-treated alloy with about 310 MPa tensile and 12-17% elongation that can be welded, anodized in colour and loaded structurally. MIC-6 is a cast plate at about 166 MPa tensile and 3% elongation that is flatter, essentially free of residual stress, faster to machine and finished on both faces. Use 6061 for parts, MIC-6 for the fixtures that hold them.
- Can MIC-6 be anodized?
- It can be anodized for corrosion protection, but the cast structure gives a grey, mottled coating that will not match another part or take a dye evenly. Do not specify cosmetic anodize on it. Electroless nickel or chem film are the usual finishes on MIC-6 fixtures.
- Can MIC-6 be welded?
- Technically yes by TIG, but the welds are porous and weak because of the cast structure, and the heat destroys the stress relief and flatness that the plate was bought for. Bolt and dowel MIC-6 assemblies together, or make the welded part from 6061.
- Is MIC-6 the same as ATP-5 or K100-S?
- They are competing cast aluminum tooling plates with similar flatness, finish and machinability and slightly different chemistries and strengths. Most shops treat them as interchangeable for fixtures. If a drawing requires a specific producer or a specific flatness or thickness tolerance, put it on the PO, because the distributor may substitute.
Processes that commonly use it
Related materials
Where to verify these values
- Arconic MIC-6 producer data sheet (properties, flatness, thickness and finish tolerances)
- Competing producer data sheets (Vista Metals ATP-5, Kaiser K100-S) for equivalents
- Aluminum Association, Aluminum Standards and Data (for the wrought alternatives)
