Weld Process Development

Once part design, material selection, and process selection have been finalized, weld process development can proceed.  It is better to start this process on demo equipment to make sure the equipment specified or recommended is appropriate; such equipment can be available at vendor laboratory or procured temporarily.  Depending on the part geometry and process, suitable fixtures and test equipment may also be required for proper evaluation. A thorough evaluation early on in the development cycle is crucial to final success of the project and should also include metallurgical evaluation including optical and SEM analysis.  If corrosion is a critical product feature, such testing should be conducted as well.

Weld evaluation after initial weld development will often reveal deficiencies in selection of materials, design, and process.  For example, metallurgical cross-sections could reveal cracks in the welds as can happen during welding with electroless nickel plating that introduces a high amount of phosphorous in the plating; changing to electroplated nickel can eliminate the cracks.  Rapid cooling rate can also produce cracks in many alloys due to formation of unstable phases or excessive residual stress on cooling; introducing a long cool down at the end of a laser pulse can avoid those issues.

Process development should also involve determination of process throughput (welds per minute) to make sure the process and power supply are fully capable of meeting the production rate.  Issues related to production such as part loading/unloading, part alignment, cleanliness, and part cooling should be discussed in detail to make sure the machine builder is aware of all the nuances.  Keep in mind that any last minute change to an automation equipment can mean weeks of delays to the project.

Once the preliminary development is complete, the final optimization will have to be carried out on the real production machine with production fixtures and setups.