Hi,
My laser weld spatter problems I have encountered were caused by dirty parts. Residue of chemicals from the washers actually.This would cause porosity in various locations among the weld joint (occasional blowouts ) scrapping the part. Our application always had the part in motion before opening the shutter and starting the weld. Stationary, which I did manually a few times, yielded a big spot and spatter in most cases. That was for test purposes though.
Let us know your details like Chadxyz requested. My experience was in a transmission plant.
I hope this helps some.
Scott
In a hundred years, it isn't going to matter anyway.