How to Specify Prepainted Aluminium Strip for Roller Shutter Slats and Garage Door Profiles

Roller shutter strip is a narrow product with very little room for error. A wide architectural coil can tolerate a minor edge issue that disappears during trimming. A 50 or 60 mm shutter strip cannot. Its slit edge, width stability and winding quality immediately affect the profile entering the roll former.

European shutter manufacturers also expect the finished slat to look consistent across windows, doors and facade elements. That makes the colour and gloss of the incoming strip as important as its mechanical properties.

Ding‘ang supplies prepainted aluminium strip for roll-formed shutter slats, roller doors and related profiles. Our starting point is not a standard catalogue colour. It is the customer's actual line: profile drawing, forming sequence, foam system, coil dimensions and approved surface sample.

What the strip becomes

Prepainted aluminium strip is used in several related products:

• double-wall roller shutter slats;

• foam-filled window shutter profiles;

• roller door and light-duty garage door profiles;

• front-mounted and top-mounted shutter systems;

• shutter boxes, covers and colour-matched accessories;

• selected solar-shading and louvre components.

German manufacturers such as ROMA describe roll-formed, double-wall aluminium profiles with stabilising or hard polyurethane foam cores. This illustrates why a shutter-strip specification must consider forming and foam processing together.

The five properties that decide whether a coil runs well

1. Width tolerance and strip camber

A narrow strip must track consistently through every forming station. Excessive width variation can change the lock geometry; camber can pull the strip to one side and mark the profile. The order should define nominal width, width tolerance, burr orientation and allowable camber using the customer's own line capability.

2. Alloy and temper

AA3003, AA3005 and AA3105 are established choices for Dingang's shutter-material range. The correct temper depends on the profile depth, hook geometry, number of forming stands and required slat stiffness.

A harder strip may improve the strength of the finished curtain but can increase springback. A softer strip may form more easily but lack the stiffness required for wide shutters. The best answer is normally found by comparing mechanical-property limits and running the proposed material through the production tool.

3. Coating flexibility

The paint film passes through the same bends as the metal. If it is too brittle, fine cracks can form at the outside radius or the coating can detach near the lock. These defects may be difficult to see immediately but become failure points during weather exposure.

A shutter-coil approval plan should therefore include a T-bend or relevant profile-forming assessment, adhesion after deformation and visual inspection of the tightest radius. EN 13523-7 provides a European test method for resistance to cracking on bending.

4. Surface friction and scratch resistance

The strip contacts guides, rollers and forming tools throughout production. Too much friction can mark the coating; too little control can make feeding unstable. Tool cleanliness, roller condition and protective-film choice all influence the result.

For visible shutter slats, the buyer should agree pencil hardness or scratch-resistance requirements, permitted pressure marks and the inspection lighting used for appearance checks.

5. Coil build and packaging

Tight, even winding helps prevent telescoping and edge damage. Coil inside diameter, maximum outside diameter, weight and winding direction must match the decoiler. Narrow slit coils need secure separation and moisture protection during sea transport without excessive strapping pressure on the edges.

A practical Dingang shutter-strip specification

Ding’ang's color-coated aluminium coil for shutter systems is available in AA3003, AA3005 and AA3105. Typical product capability shown for this series includes:

• thickness from approximately 0.4 to 1.2 mm;

• strip widths from approximately 50 to 125 mm;

• silver, white, RAL, Pantone or sample-matched colours;

• PE coating options designed around forming requirements;

• multiple coil-core diameters for different production lines.

These ranges should be treated as a starting point. For a commercial order, Ding‘ang records the agreed alloy, temper, metal thickness, strip width, coating build, colour, gloss, inside diameter, coil weight and edge requirements in the order specification.

What to test before series production

A useful trial is conducted on the customer's own line and includes the normal foam and curing process. We recommend checking:

• feeding stability at production speed;

• profile dimensions, hook engagement and winding diameter;

• surface marks after every forming station;

• coating condition at bends and punched ventilation slots;

• foam adhesion and any reaction between the coating and foam chemicals;

• colour consistency across several coils;

• finished-curtain movement, noise and stacking behaviour.

The EN 13523 series can support incoming-material control for coating thickness, gloss, colour difference, hardness, impact, bending, abrasion, humidity and other properties. The profile producer should select the parts that correspond to the actual failure risks on its line.

PE or PVDF for shutter profiles?

PE is widely used where good forming, colour choice and commercial efficiency are the priorities. It can be specified for indoor-facing and many standard exterior shutter products, provided the formulation meets the required exposure and warranty plan.

PVDF offers strong weathering performance, but it is not automatically the best answer for every tightly formed profile. The complete PVDF system must be checked for bend performance, and the additional cost must be justified by the end-use environment. For some shutter designs, a high-quality formable polyester is the more practical choice.

Colour matching for German and European ranges

Popular European shutter colours include whites, anthracite greys, aluminium greys, browns and dark architectural shades. RAL 7016, RAL 9005, RAL 9006, RAL 9007 and RAL 9016 are common reference points in the market, but a RAL number alone does not define gloss, texture or visual match to an extruded and powder-coated frame.

Where the shutter curtain must coordinate with a window, guide rail or facade component, send Ding’ang the physical master sample. We can develop the coil coating against that sample and agree an instrumental colour tolerance plus a visual approval method.

Frequently asked questions

Can one strip specification be used for every shutter profile?

Usually not. Coverage width, wall geometry, foam density, winding radius and wind-load target all affect the material requirement. Closely related profiles may share a specification after trials, but this should not be assumed.

Why does edge quality matter so much on narrow strip?

The slit edge becomes part of the formed lock or internal wall. Burrs and edge damage can mark tools, interrupt feeding, affect profile engagement or remain visible on the finished slat.

Does a thicker paint film always give better performance?

No. Thickness is only one variable. Pretreatment, primer, resin, curing, adhesion and flexibility must work together. An excessively rigid coating can perform poorly in a tight profile even when it is thick.

Can Ding‘ang supply trial coils?

Trial-coil format depends on strip width, coil diameter and the customer's line. Share these details with our export team so an appropriate sample or trial quantity can be proposed.

Talk to a supplier who understands the forming line

Send Ding’ang a profile drawing, current strip specification, monthly usage and a photograph of the finished shutter. We will use that information to recommend a substrate, coating and slit-coil format for evaluation.