EN 755 vs. EN 12020: Choosing the Right Standard for Aluminum Profiles
When you order extruded aluminum profiles, you must choose the right European quality standard. The two main standards are EN 755 and EN 12020. They look similar, but they serve completely different needs. Choosing the wrong one can lead to high costs or assembly problems.
EN 755: The Standard for General Engineering
EN 755 is the most common standard for industrial aluminum profiles. It is designed for projects where strength matters more than high visual beauty or microscopic precision.
- Key Features: Wider dimensional tolerances and standard surface requirements.
- Best Used For: Heavy machinery, structural building frames, transport engineering, and hidden internal parts.
- Main Advantage: Lower production costs and faster manufacturing times.
EN 12020: The Standard for High Precision
EN 12020 is a specialized standard for precision profiles. It sets very strict limits on size variations and guarantees a high-quality surface finish.
- Key Features: Tight dimensional tolerances (often twice as strict as EN 755) and strict surface inspection rules.
- Best Used For: Window and door systems, curtain walls, interior design elements, and electronics.
- Main Advantage: Perfect fit for moving parts and excellent results after anodizing or powder coating.
Comparison Table: Key Differences & Tolerance Examples
Note: Tolerance examples below are based on a standard precision alloy (like EN AW-6060) for a profile with a 100 mm external size and 5 mm wall thickness.
| Technical Feature | EN 755 (Standard) | EN 12020 (Precision) |
|---|---|---|
| Precision Level | Standard industrial deviations | High precision deviations |
| External Dimension Tolerance (for 100 mm size) | ±0.85 mm | ±0.45 mm |
| Wall Thickness Tolerance (for 5 mm wall) | ±0.40 mm | ±0.25 mm |
| Straightness Tolerance (over 1 meter length) | Max 1.50 mm deviation | Max 0.50 mm deviation |
| Twist Tolerance / Скручивание (over 1 meter length) | Max 1.20 mm | Max 0.60 mm |
| Concavity & Convexity / Выпуклость и Вогнутость (for 100 mm width) | Max 0.60 mm | Max 0.30 mm |
| Surface Quality | Industrial grade (minor lines allowed) | Architectural grade (no visible defects) |
| Typical Alloys | Wide range (6060, 6082, 6061, 7075) | High-finish architectural alloys (6060, 6063) |
Can You Mix Both Standards?
Yes, you can combine them to optimize your budget. A very popular mix is using EN 755 for dimensional tolerances and EN 12020 for surface quality.
This hybrid approach works perfectly if your profile does not need micro-precision to fit into a system, but will be highly visible to consumers. It gives you a beautiful, flawless finish without paying the premium price for ultra-tight structural tolerances.
Important: If you decide to mix these standards, you must clearly state this on your technical drawings and get a formal agreement from your manufacturing plant before production begins.
Annex
Avoid costly profile rejections, manufacturing delays, and tooling modifications before your blueprints go to the press. There is our technical verification sheet to instantly check alloy restrictions, uneven wall thickness limits, and face classification rules.
Technical Blueprint Review Guide
Aluminum Extrusion Technical Design Checklist:
- Standard Verification: Explicitly declare EN 755, EN 12020, or a hybrid layout (e.g., EN 755 for
dimensions, EN 12020 for surface quality) on the face of the drawing. - Alloy Compatibility: Verify that precision EN 12020 limits are only requested for architectural alloys
(e.g., EN AW-6060, EN AW-6063). Structural alloys (e.g., 6082, 7075) must use EN 755. - Wall Thickness Uniformity: Ensure wall thickness ratios between adjacent sections stay below 3:1
to avoid cooling distortions, twisting, and structural warping. - Corner Radii Optimization: Avoid perfectly sharp internal corners. Maintain a minimum radius of
0.5mm to 1.0mm to protect extrusion dies from premature wear and surface streaks. - Surface Classification: Clearly trace and color-code all visible/exposed surfaces directly on the
profile cross-section blueprint for factory coating inspection. - Dimension & Flatness Margins: Double-check that your design allows for natural flatness deviations
(up to 0.30mm under EN 12020 or 0.60 mm under EN 755 for a 100 mm span)