Laser welding of stainless steel, aluminium and thin sheet metal

Laser welding: what it is and when it pays off

Laser welding joins two metal parts by melting them along the joint with a focused laser beam. The heat stays in a small area: the piece distorts little, the bead comes out narrow and clean and grinding is often unnecessary. It pays off above all for:

• repairs of broken brackets, supports and components;
• visible joints on stainless steel, where appearance matters;
• thin sheet metal, which distorts or burns through with traditional welding.

Welding is part of COOLASER's custom metalworking, together with cutting, bending and finishing.

Stainless steel welding

Laser welding of stainless steel leaves a thin, even bead, suitable for visible parts such as casings, containers, supports and marine components. In stainless steel welding the discolouration around the joint also matters: with little heat it stays limited and, on request, it is removed with laser cleaning or with one of the metal finishing processes. Common stainless steels such as 304 and 316, often chosen for marine use, are welded.

Welding of mild steel and carbon steel

Welding of mild steel and carbon steel is carried out on request, mainly for repairs, from 0.5 to 5 mm thick. After welding, the piece must be protected from rust with paint or another treatment.

Aluminium welding

Laser welding of aluminium is possible but more delicate than welding steel, because aluminium strongly reflects the laser light and dissipates heat quickly. For this reason every aluminium welding job is assessed on the piece: the alloy, the thickness and the cleanliness of the surface, which must be free of oxide and grease, all matter. Aluminium brackets, supports, containers and components from 1 to 4 mm thick are welded.

Thin sheet metal welding

Welding thin sheet metal is the typical case where the laser makes the difference compared with traditional welding: it heats little and reduces the risk of distorting or burning through the sheet. Sheet metal from 0.5 mm thick is welded, and below 1 mm also without wire, by melting the metal of the two edges. Thin sheet metal welding is used for casings, covers, boxes and containers in stainless steel or aluminium. The parts to be joined can be prepared at the workshop with laser cutting and sheet metal bending.

Subcontract welding

COOLASER's subcontract welding is designed for machine shops, metal fabricators, craftspeople and companies that need laser joints on their own parts without owning a laser welder. Work ranges from one-off pieces to one-off or repeat batches, with the material shipped from anywhere in Italy and from abroad or supplied by the workshop. Cutting, blasting and marking for companies and professionals are grouped in the subcontract laser service.

Weldable materials

The metals the COOLASER workshop laser welds are mainly stainless steel and aluminium, then brass and titanium, including thin sheet metal; copper is not welded. For joints with a gap and fillet welds, filler wire is used, in stainless steel, aluminium or brass, chosen according to the alloy of the part (for example 308L on 304 stainless steel, 4043 on 6061 aluminium). The material can be supplied by COOLASER, or the customer ships it to the workshop.

Sizes and limits

Laser welding thicknesses depend on the metal: those in the table are welded right through, with full penetration.

How it works

Laser welding is ordered in three steps.

1. Request: the online form asks for material, thickness, quantity and the point to be welded, with photos, drawings or measurements; lead times are chosen from standard, urgent or by a set date.
2. Quote: the workshop assesses weldability, access to the joint and finish, and prepares the quote.
3. Welding and delivery: the pieces are shipped to the workshop; the welded piece comes back by shipping, throughout Italy and abroad, or, on request, is collected from the workshop.

What to prepare for the quote

For a laser welding quote, the following are needed:

• material and, if known, the alloy;
• thickness of the parts to be joined;
• photos of the piece and of the point to be welded, or a drawing (DXF, DWG, STEP or PDF);
• quantity and use of the piece, for example visible or in a marine environment.

The form accepts up to 10 files, 20 MB each and 30 MB in total; without files, measurements and a description are enough.