Plate-fin heat exchanger core design for improved manufacturing

A method for producing a heat exchanger core defining a plurality of exterior faces and an interior region, comprising the steps of:

• stacking a bottom end sheet, a plurality of alternately stacked individual hot and cold layers, and a top end sheet, each of the individual hot and cold layers including:
• a fin element forming a plurality of parallel open-ended channels adapted to pass a fluid therethrough;
• a parting sheet separating the individual hot and cold layers from the next individual hot and cold layers;
• and
• two closure bars positioned on opposite sides of the fin element, parallel to the open-ended channels and extending a length of the open-ended channels;
• wherein:
• each closure bar has an original closure bar width and a closure bar height, the original closure bar width at least as great as the closure bar height;
• each closure bar defines an inner face and an outer face, the inner face directed toward the fin element and the outer face directed away from the fin element;
• the open-ended channels of the individual hot layers are parallel to each other;
• and
• the open-ended channels of the individual cold layers are parallel to each other;
• brazing the bottom end sheet, the plurality of alternately stacked individual hot and cold layers, and the top end sheet in a brazing furnace;
• and
• removing material from each of the plurality of exterior faces by precision machining, thereby removing material from each closure bar outer face to produce a final closure bar width;
• wherein the precision machining produces two vertical core bands on each closure bar outer face, each configured to be joined to a manifold by welding, thereby forming a plurality of welding heat-affected zones that are isolated from the interior region.