Punched slugs
Blanked from rolled plate or thick strip in a press. Fast and economical for high volumes and thinner slugs. The edge has a sheared and a fractured zone, so slugs are usually tumbled to remove burrs before annealing.
Heat-treatable impact extrusion slugs
6061 Aluminium Slugs, Discs & Blanks
6061 aluminium slugs are round, square or shaped blanks used as the starting material for impact extrusion and cold forging of strong, heat-treatable parts. Supplied annealed (O) for forming and heat-treated to T6 after extrusion, they give components roughly twice the strength of 1xxx or 3xxx impacts. Metline supplies 6061 slugs, discs and blanks punched from plate or sawn from bar, to drawing, for customers worldwide.
- Alloy
- 6061 (Al-Mg-Si-Cu)
- Supply temper
- O (annealed), F, T6
- Route
- Punched or sawn
- Standard
- EN 570 · EN 573-3
What is a 6061 aluminium slug?
A slug is a measured piece of metal, usually a short disc, that a press squeezes into a finished hollow or solid part in one or a few strokes. Slugs in 6061 are chosen when the extruded part must carry real mechanical load, because 6061 can be solution heat-treated and aged after forming to reach T6 strength.
Most impact-extruded aluminium (aerosol cans, collapsible tubes, capacitor cans) is made from near-pure 1050, 1070 or 3xxx slugs, which flow very easily but stay soft. Technical impacts are different: shock-absorber bodies, brake and ABS valve housings, pneumatic cylinder tubes, airbag and sensor housings, torch bodies, electronic enclosures and heat-sink cups all need a structural alloy. 6061 is the most common answer, alongside 6082 in Europe.
Because 6061 is harder to deform than pure aluminium, the slug has to be prepared carefully. It is fully annealed to its softest condition, the surface is roughened and lubricated so the press lubricant stays in place, and its volume is held tightly so every part fills the die the same way. The quality of the slug therefore decides a large share of the scrap rate and tool life at the press.
Punched, sawn and shaped 6061 slugs
The way a slug is made affects its grain structure, edge condition and cost. The right choice depends on part size, run length and how severe the extrusion is.
Sawn slugs
Cut from extruded or cast round bar on a precision saw. Suited to thicker slugs and larger diameters, and the usual route for 6061 because the bar already has a fine, uniform structure. Faces can be lightly faced or tumbled.
Discs and blanks
Thin circles cut from 6061 sheet or plate for spinning, deep drawing, flow forming or machining. Supplied in O, T4 or T6 depending on the forming step.
Holed (annular) slugs
A centre hole is punched or drilled for tube-like parts made by forward extrusion, saving material and press force.
Preformed slugs
Coined or upset with a dome, recess or chamfer that helps the metal start to flow evenly, improving wall-thickness consistency in the first stroke.
Square and shaped slugs
Rectangular or profiled blanks for non-round impacts such as electronic housings and battery cases.
6061 chemical composition (wt %)
The limits are the registered Aluminum Association values, also used by EN 573-3 for EN AW-6061. For impact work, producers often aim towards the lower end of the magnesium and silicon ranges, which lowers flow stress during extrusion while still allowing T6 strength after heat treatment. The mill certificate reports the actual cast analysis.
| Element | Minimum | Maximum | Role in the alloy |
|---|---|---|---|
| Silicon (Si) | 0.40 | 0.80 | Forms Mg2Si with magnesium, the strengthening phase |
| Iron (Fe) | — | 0.70 | Impurity; held low for ductility |
| Copper (Cu) | 0.15 | 0.40 | Adds strength after ageing |
| Manganese (Mn) | — | 0.15 | Grain control |
| Magnesium (Mg) | 0.80 | 1.20 | Main strengthening element with Si |
| Chromium (Cr) | 0.04 | 0.35 | Restrains grain growth; helps stress-corrosion resistance |
| Zinc (Zn) | — | 0.25 | Impurity |
| Titanium (Ti) | — | 0.15 | Grain refiner |
| Others, each / total | — | 0.05 / 0.15 | |
| Aluminium (Al) | Remainder |
Properties of 6061 slugs and finished impacts
The supply temper is chosen for forming, and the service temper for the finished part. A slug is normally delivered soft, then the extruded part is heat-treated. The values below are typical properties from Aluminum Association and ASM data; specified minimums apply to the finished product form and are set by the order specification.
| Temper | Where it is used | Tensile strength | Yield strength | Elongation | Hardness |
|---|---|---|---|---|---|
| O (annealed) | Slug supply condition for extrusion | 125 MPa | 55 MPa | 25 – 30 % | 30 HB |
| T4 | Formed part, naturally aged | 240 MPa | 145 MPa | 22 % | 65 HB |
| T6 | Finished part after solution treatment and ageing | 310 MPa | 276 MPa | 12 % | 95 HB |
Physical properties (typical)
- Density
- 2.70 g/cm³
- Modulus of elasticity
- 68.9 GPa
- Thermal conductivity (T6)
- 167 W/m·K
- Electrical conductivity (T6)
- 43 % IACS
- Thermal expansion (20 – 100 °C)
- 23.6 µm/m·°C
- Melting range
- 582 – 652 °C
How 6061 slugs are prepared for the press
- CutSlugs are punched from plate or sawn from bar to a controlled volume. Weight, not just thickness, is the real target, because the die fills by volume.
- DeburrBarrel tumbling or vibratory finishing removes burrs and sharp edges, which would otherwise fold into the part as laps.
- AnnealA full anneal (typically around 415 °C, then slow cooling) brings 6061 to the O temper, with low flow stress and uniform grain. Batch or continuous furnaces are used; atmosphere control limits surface oxide.
- Surface treatShot blasting or tumbling gives a roughened surface that holds lubricant. Some users specify a conversion coating before lubrication for severe extrusions.
- LubricateZinc stearate or a similar dry lubricant is applied by tumbling, either by the slug supplier or at the press, by agreement.
- Inspect and packSlugs are checked for diameter, thickness or weight, flatness and surface, then packed in sealed, moisture-protected cartons or drums.
Annealing cycles vary with the furnace and slug size. The exact cycle and hardness target are agreed with the press user and recorded with each lot.
Standards and equivalent designations
Impact extrusion slugs in Europe are specified under EN 570, which covers inspection, delivery conditions and tolerances on dimensions and form for slugs taken from wrought products. Elsewhere, slugs are normally bought to the customer's drawing with the alloy certified to the source product standard.
| System | Designation | Related standard |
|---|---|---|
| Aluminum Association / UNS | 6061 / A96061 | Source bar ASTM B221; source plate ASTM B209 |
| European (EN) | EN AW-6061 (AlMg1SiCu) | EN 570 slugs; EN 573-3 composition |
| ISO | AlMg1SiCu | ISO 209 composition |
| German Werkstoff | 3.3211 | — |
| Japan (JIS) | A6061 | JIS H4040 (rod), JIS H4000 (plate) |
| India (IS) | 65032 | IS 733 (bar), IS 737 (plate) |
Sizes, tolerances and slug weights
Supply options
- Shape
- Round, annular (holed), square, rectangular or to drawing
- Diameter / thickness
- Made to the press user's drawing; sawn slugs suit thicker and larger blanks, punched slugs thinner ones
- Temper
- O (annealed) as standard; F, T4 or T6 blanks for machining or other forming
- Surface
- Sawn or sheared, tumbled, shot-blasted, with or without lubricant
- Tolerance
- To EN 570 or to drawing; weight tolerance agreed per part
- Packing
- Sealed cartons, drums or crates with desiccant, labelled by lot
A solid round slug weighs π/4 × D² × t × 2.70 g/cm³. The table gives quick reference weights in grams; the circle and disc weight calculator handles any size.
| Diameter (mm) | t = 5 mm (g) | t = 10 mm (g) | t = 15 mm (g) | t = 20 mm (g) | t = 30 mm (g) |
|---|---|---|---|---|---|
| 20 | 4 | 8 | 13 | 17 | 25 |
| 30 | 10 | 19 | 29 | 38 | 57 |
| 40 | 17 | 34 | 51 | 68 | 102 |
| 50 | 27 | 53 | 80 | 106 | 159 |
| 60 | 38 | 76 | 115 | 153 | 229 |
| 80 | 68 | 136 | 204 | 271 | 407 |
| 100 | 106 | 212 | 318 | 424 | 636 |
| 120 | 153 | 305 | 458 | 611 | 916 |
| 150 | 239 | 477 | 716 | 954 | 1431 |
Parts made from 6061 slugs
- Automotive: shock-absorber and damper bodies, ABS and brake valve housings, steering and sensor housings, airbag inflator parts
- Pneumatics and hydraulics: cylinder tubes, end caps, accumulator shells and fittings
- Electronics: motor and sensor housings, enclosures, heat-sink cups and LED bodies
- Lighting and tools: torch and flashlight bodies, power-tool housings
- Defence and safety: canisters, fuze bodies and extinguisher components
- Sports and consumer goods: bottle and flask bodies, camera parts, bicycle components
Where the part does not need T6 strength, a softer alloy is usually more economical: see 1070 slugs for cans and tubes, 3003 slugs for slightly stronger containers, or 6063 slugs for easier-flowing heat-treatable parts.
6061 compared with other slug alloys
| Property | 1070 / 1050 | 3003 | 6063 | 6061 |
|---|---|---|---|---|
| Heat-treatable | No | No | Yes | Yes |
| Flow stress in O temper | Lowest | Low | Moderate | Higher |
| Typical finished-part strength | About 70 – 100 MPa | About 110 – 150 MPa | About 240 MPa (T6) | About 310 MPa (T6) |
| Press force and tool load | Lowest | Low | Medium | Highest of the four |
| Typical parts | Aerosol cans, tubes, capacitor cans | Cans, battery shells | Housings, heat sinks | Structural and pressure parts |
The trade-off is simple: the stronger the alloy, the higher the press force, the shorter the tool life and the more care the slug needs. 6061 is the right choice when the part must be heat-treated for strength; otherwise, 6063 or a non-heat-treatable alloy will extrude faster and more cheaply.
How to order 6061 slugs
- SpecifyDrawing or diameter, thickness, hole size and weight target; temper and hardness limit; surface treatment and lubricant; quantity.
- ConfirmWe confirm the cutting route (punched or sawn), tolerances, certification and delivery terms (EXW, FOB, CIF or DAP).
- SampleFor new parts, a trial lot lets your press team confirm fill, wall thickness and scrap rate before volume orders.
- DocumentEach lot ships with an EN 10204 3.1 mill test certificate covering chemistry, plus hardness or dimensional records as agreed.
- ShipMoisture-protected export packing, by sea or air, to your plant.
References and standards
- EN 570 – Aluminium and aluminium alloys: impact extrusion slugs obtained from wrought products, specifications
- EN 573-3 – Chemical composition and form of wrought products
- ASTM B221 – Extruded Bars, Rods, Wire, Profiles, and Tubes
- ASM Handbook Vol. 14A – Cold Extrusion of Aluminium Alloys
- The Aluminum Association – International Alloy Designations and Chemical Composition Limits
6061 aluminium (aluminum) slugs: frequently asked questions
Why are 6061 slugs supplied in the O temper?
Annealing to O gives the lowest flow stress and the most uniform grain, which reduces press force, protects the tooling and lets the metal fill the die evenly. Strength is restored afterwards by solution heat treatment and ageing of the finished part to T6.
Can a part impact-extruded from 6061 be heat-treated to T6?
Yes. That is the main reason to choose 6061. The extruded part is solution treated at about 530 °C, quenched and artificially aged, reaching typical properties of around 310 MPa tensile and 276 MPa yield strength.
Is a punched or a sawn slug better?
Punched slugs are cheaper at high volume and suit thinner blanks. Sawn slugs from extruded bar suit thicker and larger blanks and give a more uniform structure through the slug. For severe 6061 extrusions, sawn slugs are common.
What surface treatment do 6061 slugs need?
Usually tumbling to remove burrs, then shot blasting or tumbling to roughen the surface so it holds lubricant, followed by a dry lubricant such as zinc stearate. Some severe extrusions also use a conversion coating.
How is slug weight controlled?
The die fills by volume, so slugs are cut to a target weight with an agreed tolerance. Sawn slugs are adjusted by length; punched slugs by plate thickness control. Weight sampling is recorded for each lot.
Do you export 6061 slugs?
Yes. Metline supplies slugs and blanks worldwide from Mumbai, with mill certificates, moisture-protected packing and shipment on EXW, FOB, CIF or DAP terms.
Need 6061 slugs for impact extrusion?
Send your slug drawing, temper, surface treatment, quantity and destination. We will confirm the route, tolerances and a delivered price.
