Rolled plate, T651
Rolled, solution treated, quenched, stretched 1.5 – 3 % and aged. Low residual stress and good flatness. Thickness typically 6 – 200 mm, widths to about 2500 mm.
Machining stock guide
6061 Tooling Plate and Block for CNC Machining
For jigs, fixtures, mould plates and machined structures, 6061 is supplied as rolled T651 plate, forged T652 block or precision-milled blanks cut to size. Each route trades strength, flatness, internal soundness and cost differently. This guide explains how to choose between them, what surface and tolerance to ask for, and when cast tooling plate or another alloy is the better buy.
- Grade
- 6061 (EN AW-6061)
- Forms
- Rolled plate · forged block · milled blanks
- Tempers
- T651, T652, T6
- Typical hardness
- About 95 HB
Why machinists choose 6061 for tooling
A good tooling material must cut quickly, hold size when material is removed, take a durable surface finish and be available in large sections at a sensible price. 6061-T651 meets all four: it machines at high spindle speeds with short chips, has low residual stress after stretching, anodises well and is rolled by mills worldwide.
It is not the hardest or most stable option. 7075-T651 is roughly twice as strong and is preferred for high-load mould inserts, while cast tooling plates are flatter and more stable but weaker. 6061 sits in the middle: strong enough for most fixtures and mould bases, stable enough for precision work, and economical in large sizes.
Plate, block and blank: the supply options
Forged block, T652
Forged from ingot or billet, solution treated, compressed about 1 – 5 % to relieve stress, then aged. Dense, with a refined grain through the section; used for large mould blocks and highly stressed parts.
Saw-cut blocks
Cut from thick plate to your dimensions with a small allowance. The economical route for most fixture and mould work.
Precision-milled plate
One or both faces milled flat and parallel to a stated thickness, often with protective film. Goes straight onto the machine table.
Ground plate
Surface-ground for gauges, inspection bases and assembly plates that need very fine finish and flatness.
Six-side-milled blanks
Squared on all faces to close tolerances, so the first operation can start from a known datum.
6061 plate vs forged block vs cast tooling plate
| Property | 6061-T651 rolled plate | 6061-T652 forged block | Cast tooling plate |
|---|---|---|---|
| Typical yield strength | About 275 MPa | About 255 – 275 MPa | About 100 – 150 MPa |
| Residual stress | Low | Low | Very low |
| Flatness as supplied | Good; better when milled | Machined to size | Excellent, precision-milled |
| Internal soundness | Good; UT on request | Very good | Good, fine porosity possible |
| Anodising | Excellent | Excellent | Fair, often uneven |
| Weldability | Good | Good | Limited |
| Relative cost | Low | High | Medium |
| Best for | Fixtures, mould plates, frames | Large moulds, loaded parts | Vacuum tables, gauges, bases |
Values are typical and depend on section size and supplier. Forged block properties fall slightly with section thickness; confirm against the order specification (for example ASTM B247 / AMS 4127 for forgings).
6061 composition and properties for tooling
| Element | Min % | Max % |
|---|---|---|
| Silicon (Si) | 0.40 | 0.80 |
| Iron (Fe) | — | 0.70 |
| Copper (Cu) | 0.15 | 0.40 |
| Manganese (Mn) | — | 0.15 |
| Magnesium (Mg) | 0.80 | 1.20 |
| Chromium (Cr) | 0.04 | 0.35 |
| Zinc (Zn) | — | 0.25 |
| Titanium (Ti) | — | 0.15 |
| Others, each / total | — | 0.05 / 0.15 |
| Aluminium (Al) | Remainder |
| Property (T651 / T652) | Typical value | Why it matters for tooling |
|---|---|---|
| Tensile strength | 310 MPa | Resists clamping and moulding loads |
| Yield strength | 276 MPa | Sets the load before permanent deformation |
| Hardness | About 95 HB | Resists dents and thread wear better than cast plate |
| Modulus | 68.9 GPa | Stiffness is a third of steel: allow thicker sections |
| Thermal conductivity | 167 W/m·K | Fast, even cooling of moulds and heat-sinking fixtures |
| Thermal expansion | 23.6 µm/m·°C | Measure parts at a controlled temperature |
For design, use the specified minimums of the order standard (for example 290 MPa tensile and 240 MPa yield for T651 plate up to 100 mm under ASTM B209), not the typical values above.
Common 6061 block sizes and weights
Block weight is length × width × thickness × 2.70 g/cm³. The table gives quick figures for popular fixture and mould sizes; a 10 % allowance for saw kerf and clean-up is sensible when budgeting material from full plate.
| Block size (mm) | Volume (dm³) | Mass (kg) |
|---|---|---|
| 300 × 300 × 25 | 2.25 | 6.1 |
| 400 × 400 × 30 | 4.80 | 13.0 |
| 500 × 300 × 40 | 6.00 | 16.2 |
| 500 × 500 × 50 | 12.50 | 33.8 |
| 600 × 400 × 60 | 14.40 | 38.9 |
| 800 × 500 × 80 | 32.00 | 86.4 |
| 1000 × 500 × 100 | 50.00 | 135.0 |
| 1000 × 600 × 150 | 90.00 | 243.0 |
| 1200 × 800 × 200 | 192.00 | 518.4 |
Standard squares such as 300 × 300 mm and 400 × 400 mm are popular for automation and measuring fixtures. Larger blocks are cut from plate up to about 2500 mm wide, or forged when the section is thicker than rolled plate allows.
What to put on a tooling plate enquiry
Checklist
- Form and temper
- 6061-T651 plate, 6061-T652 forged block, or milled blanks
- Dimensions
- Finished size plus machining allowance, or "milled to" size
- Surface
- Saw-cut, one-side milled, two-side milled, ground, or six-side milled
- Flatness and parallelism
- State the value over a length (for example per 300 mm) if it is critical
- Inspection
- Ultrasonic class (ASTM B594 / AMS-STD-2154), dimensional report
- Certification
- EN 10204 3.1 mill certificate
Machining and finishing 6061 tooling stock
- Use sharp carbide end mills with two or three flutes, high positive rake and polished flutes to avoid built-up edge
- Run high spindle speeds with flood coolant or mist; 6061 tolerates aggressive feeds
- Remove material evenly from both faces and finish after a relaxation pass to hold flatness
- Use thread inserts in fixtures that are bolted and unbolted often; aluminium threads wear
- Hard anodise (Type III) wear surfaces such as locating faces and slideways
- Hold inspection at 20 °C; a 500 mm plate grows about 0.012 mm for every degree
Typical uses of 6061 tooling plate and block
- CNC fixtures: sub-plates, tombstones, vice jaws and modular fixture bases
- Moulds: prototype and short-run injection moulds, blow moulds, thermoforming tools and mould backing plates
- Automation: robot end-effectors, gantry plates, test and inspection fixtures
- Semiconductor and vacuum: chamber bodies, wafer-handling plates and frames
- Machinery: machine beds, cover plates and structural brackets
References and standards
- ASTM B209 – Aluminum and Aluminum-Alloy Sheet and Plate
- ASTM B247 – Aluminum and Aluminum-Alloy Die Forgings, Hand Forgings, and Rolled Ring Forgings
- ASTM B594 – Ultrasonic Inspection of Aluminum-Alloy Wrought Products
- ANSI H35.1 – Alloy and Temper Designation Systems for Aluminum
6061 tooling plate and block: frequently asked questions
Is 6061 tooling plate the same as cast tooling plate?
No. 6061 is a wrought alloy supplied as rolled plate or forged block. Cast tooling plates are made from different casting alloys, are flatter and more stable, but have roughly half the strength and do not anodise as evenly.
What is the difference between T651 and T652?
Both are solution treated and aged. T651 is stress-relieved by stretching and applies to rolled plate; T652 is stress-relieved by compression and applies mainly to forgings and blocks.
Is 6061 or 7075 better for moulds?
6061 is cheaper, anodises better and suits prototype and short-run moulds. 7075 is harder and stronger, giving longer life and better edge retention for production moulds.
Can you supply 6061 plate milled to thickness?
Yes. Plate and blocks can be supplied saw-cut, milled on one or both faces, ground, or six-side milled to your tolerances.
Do thick 6061 blocks need ultrasonic testing?
For moulds and critical tooling it is strongly recommended. Ask for testing to ASTM B594 or AMS-STD-2154 at the class your part requires.
Need 6061 tooling plate or blocks?
Send sizes, surface condition, quantity and destination. We will reply with the best supply route and a delivered price.
