Feb
3
Cost Reductions in Welded Tungsten Lamp Lead Seals
Seal Grade Tungsten for Lamp Leads
The making of welded tungsten lamp leads requires the use of seal grade tungsten cuts to insure a gas tight seal of the lamp envelope.
Grinding to Remove Surface Defects
The typical seal grade tungsten used in the past was made from rod that was centerless ground with diameter reductions as high as ten percent. The grinding removed surface defects such as splits and laps providing a good glass to metal seal. The process of making and grinding rod adds significantly to the cost of the tungsten seal material.
Cost Reduction with Cut Wire and Etching
To reduce this cost the seals are being made from cut wire then chemically etchted to remove or open any defects which helps make a tight glass to metal seal. Some of the issues with this these type of seals are trapped carbon residue from the wire drawing process. In some cases additional surface cleaning is required to prevent the formation of bubble lines in the seal area.
