As with all welding processes, laser welding must be carefully controlled to ensure quality. A poorly controlled process opens the door to cracks, porosity, insufficient penetration, and lack of fusion – any of which could cause failure of the weld joint if present in sufficient amounts. 

You might be saying to yourself, “These welds are so tiny, how in the world am I supposed to ensure their quality?!” The good news is there are established methods for ensuring quality of laser welds. Here are the three I believe to be most important: 

1. A Written, Qualified Welding Procedure

In the welding world, document welding procedures using a Welding Procedure Specification (WPS). A WPS is a document that specifies all of the essential variables that must be defined and controlled when making a particular weld joint. Some of these essential variables are joint design, base metal types, filler metal types, shielding gases, laser type, and laser settings. 

A WPS is usually required to be qualified (or proven) through testing. This usually involves making test welds following the WPS, and subjecting the test welds to appropriate materials tests to ensure they meet all engineering requirements. WPS qualification tests may include nondestructive inspection (visual, penetrant, x-ray, leak check), or destructive testing (bend, tensile, hardness, metallography). Exact testing requirements are usually specified in the contract documents (engineering drawings or quality specifications). WPS qualification test results are documented in a Procedure Qualification Record (PQR). 

2. Qualified Welding Operators

The person operating the laser welding machine should be trained and should demonstrate his/her ability to produce welds that meet the applicable quality requirements. Training should include not only proper operation of the equipment, but also the safety considerations of working with lasers. 

Demonstration of the operator’s ability usually involves testing similar to WPS qualification. Operator qualification may include nondestructive and/or destructive testing, depending on contract requirements. The results of this testing are documented in an Operator Process Qualification Test Record (OPQTR), or similar form. 

3. Quality Inspection of Welded Production Parts

To ensure the ongoing quality of laser welded parts, a manufacturer should have a quality assurance procedure in place. The details of this quality assurance procedure may vary from organization to organization, or from contract to contract. Most will include sampling plans, inspection procedures, acceptance criteria, and periodic destructive evaluation. 

Laser welding comes with many benefits. 

If properly controlled, it can produce reliable, high-quality weld joints in your product.