K. S. Allen, Bellman-Melcor, Tinley Park, IL; S. L. Feldbauer, Abbott Furnace Company, St. Marys, PA
This paper presents a comparison between the use of copper braze paste and copper preforms in atmosphere furnace brazing applications. Attention is directed towards obtaining the true cost of which method is the most economical alternative for a given application. This analysis is more complicated than simply reviewing the cost of the brazing filler material. Cost must also address first time throughput relative to scrap and rework. It also addresses the ability to efficiently load the correct number of parts on the belt with a prescribed amount of labor. Application of the copper filler metal is reviewed by illustrating available methods of paste application. Squeeze bottles, air operated dispensers and positive displacement devices are explained and contrasted. The versatility of paste is compared to the wide variety of pre-engineered shapes which are available as preforms. The authors review the way paste and solid forms react in the furnace and discuss the problems and issues associated with each material alternative. Identification and measures to control issues of slump, carbon residue and flash of braze filler metals will be discussed. Attendees will gain an appreciation of the advantages of each option and be better equipped to make informed decisions on which alternative provides the greatest benefit for a particular application.
Summary: A brazing material specialist and the technical director of a major manufacturer of brazing furnaces present a comparison between the use of copper braze paste and copper preforms in furnace brazing applications. Attention is directed to production ramifications, cost parameters, performance capabilities, and the short and long-term impact of this decision on brazing equipment.
Detailed evaluations are presented of those situations in which either paste or preforms would be the preferred method of material introduction. Attendees will receive a fresh and insightful presentation of the advantages of each option and will be better equipped to make informed decisions on methods of filler metal introduction.
