What is the difference between 6005A vs 6063 Aluminium Alloy?

In the UK signage industry, the choice of aluminium alloy for sign frames, channels, and posts has a direct impact on the strength and durability of the finished sign. Two common alloys are 6063-T6 (widely used traditionally for sign extrusions) and 6005A-T6 (a higher-strength alternative gaining popularity). Both are 6000-series aluminum alloys (Al-Mg-Si family) but they differ in mechanical properties and extrusion characteristics. This comparison highlights their technical performance differences and what they mean for sign makers in terms of rigidity, strength, and usability in typical signage applications. We focus exclusively on signage industry needs such as road signs, post-and-panel signs, and related sign structures.

Common Alloys Used in Signage Extrusions

6063-T6 – Alloy 6063 in T6 temper is a medium-strength “architectural” alloy commonly used for extruded sign frames, channels, and posts It is popular because it extrudes very well into intricate shapes and yields a smooth surface finish ideal for visible sign components. Many sign industry extrusions (e.g. sign channels and small posts) have traditionally been made from 6063-T6 due to its good balance of strength, corrosion resistance, and appearance

6082-T6 – Alloy 6082 is a higher-strength 6000-series alloy sometimes used for structural sign components. Some UK sign systems (e.g. heavy-duty channels or large sign supports) specify 6082-T6 because it has one of the highest strengths in the 6000 series. However, 6082 is a bit harder to extrude into very thin or complex profiles, so it’s typically used where maximum strength is required and simpler shapes are acceptable.

6005A-T6 – Alloy 6005A in T6 temper is a medium-high strength alloy that bridges the gap between 6063 and 6082. In terms of strength it is closer to 6082, but it offers better extrusion characteristics than 6082. This makes 6005A very attractive for sign profiles that need more strength and rigidity than 6063 can provide, without sacrificing too much extrudability or surface finish quality. Some UK suppliers (such as Sign Trade Supplies) have adopted 6005A-T6 for their aluminum sign channels and posts to ensure maximum strength and rigidity for installed signs (reducing issues like flexing or deformation under load).

Alloy 6063-T6 – Properties & Signage Performance

6063-T6 is often referred to as an “architectural alloy” and is known for its excellent extrudability and good appearance. Key properties and characteristics of 6063-T6 in sign-making:

• Strength: 6063-T6 is a medium-strength aluminum. Its typical minimum yield strength is around 160–170 MPa, with ultimate tensile strength about 195–215 MPa. For thin-walled profiles (common in sign frames), values are about 170 MPa yield and 215 MPa tensile. This level of strength is adequate for many small to medium sign applications, but it is lower than that of 6005A-T6 (as we’ll see below).

• Rigidity: The elastic modulus of aluminum is similar across alloys (~69–70 GPa), so 6063’s initial stiffness is on par with other alloys. However, because of its lower yield strength, a 6063 section will begin to permanently bend (yield) under a lower load compared to a stronger alloy. In practice, sign structures made with 6063 may exhibit more flex or need thicker profiles to meet wind load requirements, especially for large signs.

• Extrudability & Profile Design: 6063 excels at being extruded into complex, thin-walled shapes. It can accommodate wall thicknesses and intricate designs that higher-strength alloys might struggle with. In fact, engineers note that 6063 allows 25–35% thinner wall sections than stronger alloys like 6061 for a given extrusion. This means sign channels or frames made from 6063 can be designed with fine detail and still come out of the die smoothly. The alloy flows easily, which is why it’s the most common choice for decorative and intricate extrusions (window frames, etc.). For sign makers, this translates to reliable production of profiles like clipping channels, hollow posts, or interlocking frames without excessive press force or risk of cracking.

• Surface Finish: One of 6063’s greatest advantages is its smooth surface finish. It’s known to produce very clean, glossy mill finishes and takes anodizing and painting extremely well. In signage, where appearance (lack of surface defects, good paint adherence) matters, 6063 delivers. It’s rated “very good” in surface quality for extrusion. This makes it easier to powder-coat or anodize to a high decorative standard – useful for sign posts or frames that remain visible.

• Corrosion Resistance: 6063 has excellent resistance to corrosion, particularly in normal outdoor environments. This is important for signs, which face weather exposure. When powder coated or anodized, 6063 profiles hold up for many years with minimal corrosion issues.

• Weldability & Fabrication: 6063-T6 is readily weldable (often using 4043 or 5356 filler) and can be machined or worked if needed. Its machinability is rated as “good” and cold formability is acceptable – though in T6 temper it’s not as formable as in T4. In practice, welding sign frames or brackets to 6063 posts is common and generally trouble-free.

In summary, 6063-T6 is the standard alloy for many sign extrusions because it is easy to work with and has a decent strength-to-weight ratio. However, its medium strength means that in heavy-duty applications (large signs, high wind loads, or situations where bolts are torqued very tight), 6063 can be the weak link – potentially leading to bending or localized deformation if the profile walls are thin.

Alloy 6005A-T6 – Properties & Advantages for Signage

6005A-T6 is a heat-treated alloy that offers a step up in strength for extruded profiles. It is often described as having properties between 6061 and 6082, meaning it’s stronger than the common 6060/6063 series, but can be extruded easier than 6082. Key features of 6005A-T6 for sign industry use:

• Strength: 6005A-T6 is significantly stronger than 6063-T6. Typical minimum yield strength is around 200–225 MPa, with ultimate tensile strength in the range of 250–270 MPa. For example, an open-profile extrusion in 6005A-T6 has ≥225 MPa yield and ~270 MPa tensile strength. This is roughly a 30–35% increase in strength compared to equivalent 6063-T6 profiles. The higher strength gives 6005A profiles a greater load-bearing capacity – they can sustain higher stresses before yielding or failing.

• Hardness & Wear: Along with strength, 6005A is harder – about 85–90 Brinell hardness vs ~75 HB for 6063. This increased hardness means the material is less prone to surface denting or wear. In practical terms, a 6005A sign channel will be more resistant to the kind of gouging or distortion that can happen when bolts, clips, or other hardware bite into the aluminum under tension.

• Rigidity: As noted, the elastic modulus is essentially the same ~70 GPa, so 6005A isn’t “stiffer” in the elastic sense. However, since it can take higher stress without permanent deformation, a sign post or frame made of 6005A will maintain its shape under higher loads. For example, under high wind pressure, a 6005A post can withstand more force before it bends, compared to a similar 6063 post. The result is effectively better structural integrity under load – sign installers and engineers might say it “feels more rigid” because it doesn’t yield as easily.

• Extrudability: One reason 6005A isn’t as ubiquitous as 6063 is that it is slightly more challenging to extrude. The alloy’s chemistry (with slightly higher silicon and added manganese) means the material flow is not as forgiving for very thin or highly complex shapes. It is noted that “it is difficult to produce thin-wall or complicated extrusions in 6005/6005A”. In other words, if a profile requires extremely fine details or minimal wall thickness, 6005A might struggle where 6063 would succeed. However, 6005A still extrudes better than 6082 and is considered to have “good” extrudability (comparable to 6063 in many cases). Modern extrusion presses and dies can accommodate 6005A for most standard sign shapes (channels, hollow tubes, angles, etc.) without issue. The main practical limitation is that a designer might choose a slightly thicker wall or a simpler shape for 6005A profiles to ensure smooth production. For example, a sign channel that might be 2.0 mm thick in 6063 could be made 2.5 mm in 6005A to aid manufacturability – but thanks to the higher strength, it would still outperform the thinner 6063 channel in strength.

• Surface Finish: As-extruded 6005A can have a good surface finish, though not quite as flawless as 6063. It’s often rated “good” as opposed to “very good” for 6063. In practice, this means a 6005A extrusion might have a slightly rougher texture or more grain lines straight from the press, and it may require a bit more attention in finishing processes. For a signage supplier with proper equipment, these differences are minor – profiles can be sanded, anodized, or powder coated to a high-quality finish such that the end user would not notice any difference. One source notes that 6005A actually has a better mill surface finish than 6061/6082 alloys. So while 6005A’s finish is a tick below 6063, it’s still quite acceptable for sign usage. With correct pretreatment and coatings, the finish quality of 6005A signs can be made virtually indistinguishable from 6063 for all practical purposes.

• Corrosion Resistance: 6005A exhibits excellent corrosion resistance, nearly on par with 6063. It’s well-suited for outdoor use and is often used in architectural and structural applications where weather exposure is expected. For instance, 6005A has been used in transit and infrastructure projects due to its corrosion performance. In the context of sign posts and channels, 6005A (especially when powder coated) will easily meet longevity requirements in typical environments. Like 6063, in very harsh marine or industrial environments, proper coating (e.g. polyester powder in grey/black) is recommended to maximize life.

• Weldability & Fabrication: Despite the higher strength, 6005A remains very weldable. It is typically welded with 4043 filler (or 5356 for certain cases) and has excellent weldability ratings (gas, arc, resistance). This is important if sign brackets or base plates need to be welded to a post made of 6005A – it can be done without much difficulty, maintaining good joint strength. Machining 6005A is a bit harder than 6063 (since it’s harder material), but it’s still machinable with proper tooling (rated “fair” machinability). Generally, standard fabrication techniques used for 6063 will also work for 6005A, with slight adjustments.

In summary, 6005A-T6 provides a higher-performance alternative for sign profiles. It brings a significant boost in strength and durability, at the cost of a slight increase in production complexity (extruding and finishing). For sign makers and end-users, the benefit is greater rigidity and load resistance – signs that are less likely to bend in high winds, and sign channels that won’t crush or deform easily when bolts are tightened. The downsides (a bit more effort to extrude and finish) are usually handled by the manufacturer’s expertise, meaning the end customer simply gets a stronger product.

Performance Comparison of 6063-T6 vs 6005A-T6 in Signage

To directly compare 6063-T6 vs 6005A-T6 for sign profile use, the following points summarize their differences and implications:

• Mechanical Strength: Alloy 6005A-T6 is notably stronger than 6063-T6. A 6005A section can handle higher stress and heavier loads. For instance, 6005A-T6 has ~225 MPa yield strength vs ~170 MPa in 6063-T6. Ultimate tensile strength is ~270 MPa vs 215 MPa. This ~30% strength increase means signs built with 6005A can sustain more force (from wind, impacts, or installation torque) before permanently bending or breaking. In practical terms, a 6005A sign post can support a larger sign panel (or endure higher wind speeds) than a 6063 post of the same dimensions.

• Rigidity and Load Resistance: Although both alloys have similar stiffness initially, 6005A’s higher yield point gives it the edge in rigidity under working loads. A 6005A sign post will remain straight under forces that might cause a 6063 post to yield and bend. This is critical for tall post-and-panel signs or wide signs facing wind pressure. Likewise, a channel rail made of 6005A is less likely to flex or twist when the sign panel is under stress. As one manufacturer notes, using strong alloys leads to “excellent structural rigidity and resistance to deformation at fixing points” on signs. This directly addresses a common issue: 6063 channels with thinner walls might deform where bolts clamp them, whereas 6005A channels stay intact.

• Behavior During Installation (Bolting and Fixing): Installers often secure signs to posts using M8 bolts with square heads that lock into the aluminum channel on the sign. With softer or thinner 6063 channels, over-tightening the nut can distort the channel or cause the square bolt head to tear out and spin, damaging the sign mounting. The stronger and harder 6005A channel greatly reduces this risk – it can handle higher bolt torque without crushing. This means a more forgiving installation: even if a worker slightly over-tightens, the sign is less likely to fail at the connection. In summary, 6005A provides better safety margin against installer error or heavy-handed tightening, ensuring the sign stays securely attached.

• Profile Thickness and Weight: To achieve the needed strength, a 6063 profile might have to be made thicker or heavier. 6005A, being stronger, can potentially allow a slightly thinner profile for the same strength, or more commonly, the same profile thickness yields higher strength. Some “medium duty” sign channels made in 6063 could be upgraded to “high strength” channels in 6005A without increasing bulk – resulting in a stronger product with no change in outward design. On the other hand, if a very thin 6063 wall was at the limit of manufacturability, 6005A might require that wall to be thickened a bit to extrude well. Overall, any weight difference is minor, but it’s a consideration in design: 6005A lets you achieve higher performance possibly with the same dimensions, which is a net benefit for sign weight-to-strength ratio.

• Extrusion and Shape Capability: For most standard sign profiles (round/square posts, U-channels, angles, etc.), 6005A can be used without problem. However, if a sign system uses a very intricate extrusion (with multiple internal cavities or extremely thin sections), 6063 would handle that complexity more easily. In practice, sign industry profiles are relatively simple, and 6005A is fully capable of those shapes – especially with today’s extrusion presses. The difference might be seen in production throughput or scrap rate: 6063 can be extruded a bit faster and with slightly lower scrap risk on tough shapes, whereas 6005A might need slower press speeds or higher temps to ensure quality. These are manufacturing nuances; from the end-user perspective, both alloys can produce the needed profiles, but 6063 is considered a bit more versatile for unusual shapes, while 6005A is used for robust standard shapes.

• Finish and Appearance: Once painted or anodized, it’s difficult to tell a 6063 sign profile from a 6005A profile. 6063’s advantage is in how easy it is to achieve that smooth finish. A 6063 extrusion comes out cleaner (“very good” surface) vs a 6005A (“good” surface). This means finishing processes (polishing, anodizing, powder-coating) might take slightly more work for 6005A to reach an equally smooth cosmetic result. Importantly, with proper powder coating equipment and technique, 6005A profiles can be finished to the same high standard, making any differences insignificant to the end user. The slight reduction in cosmetic ease is a worthy trade-off for the strength gain in applications where the profile is not highly visible or where a durable coating is applied. Both alloys can be powder coated in common sign colors (like black, grey, white) with excellent adhesion. (Sign makers generally use polyester or epoxy powders which cover minor surface differences easily.)

• Corrosion and Long-Term Performance: Both 6063-T6 and 6005A-T6 are aluminum alloys that naturally resist rust and corrosion. In typical UK climate exposure, both will last for decades, especially if painted. 6063 might have a tiny edge in certain corrosive environments (because it has no added copper and slightly less alloy content overall), but in practice 6005A also has no significant copper and has “excellent corrosion resistance” as well. There is no drawback to using 6005A in terms of weather resistance for signs. Maintenance and life expectancy of the sign structure will be comparable between the two alloys; the deciding factor is more the coating quality and thickness than the alloy itself.

• Cost and Availability: The question of cost was not the main focus, but generally 6005A extrusions may be slightly more expensive per kg than 6063 because of the higher strength (and possibly lower production yield). One industry source notes 6005 tends to be priced a bit higher due to its enhanced properties. However, for the relatively small material volumes in sign projects, this difference is marginal. The benefit (reduced failures, longer life, fewer service calls to fix bent signs) can easily outweigh a small material cost difference. Both alloys are readily available from extrusion suppliers in the UK, though 6063 is very common stock and 6005A might be offered by specialized sign supply companies as a premium option.

Below is a side-by-side summary of the key differences between 6063-T6 and 6005A-T6 as they pertain to sign profile performance:

Comparison Table: 6063-T6 vs 6005A-T6 (Signage Profiles)

Conclusion

In the signage industry, switching from the standard 6063-T6 alloy to a higher-grade 6005A-T6 alloy for sign profiles can yield substantial performance improvements. The 6005A alloy delivers greater rigidity and strength – ensuring that sign channels don’t buckle when bolts are tightened and sign posts stay straight under heavy wind loads. Meanwhile, any downsides (a bit more care needed during extrusion and finishing) are mitigated by modern equipment and processes, resulting in a finished product that looks just as good and lasts just as long. Sign makers using 6005A can provide end customers with more robust signs that have higher safety margins and durability, which is especially important for larger signage installations (like road signs or tall post-mounted signs in windy areas).

Ultimately, both alloys have their place: 6063-T6 remains an excellent choice for complex or highly decorative profiles, or where cost needs to be minimized for smaller signs. However, for critical structural components of signs – such as sign fixing rails and posts that must not fail – the use of 6005A-T6 gives peace of mind through its higher technical performance. By understanding these differences, signage professionals can choose the appropriate alloy for each job, balancing ease of fabrication with the demanded strength. In summary, 6005A T6 vs 6063 T6 comes down to strength vs. ease: when strength and rigidity are paramount, 6005A shines; when extreme formability and ultra-smooth finish are needed, 6063 is the go-to. In practice, many sign suppliers now offer profiles in 6005A specifically to ensure maximum strength for their customers’ projects – a trend that highlights the industry’s commitment to safety and quality.