T

HEADER PLATES he header plates are an in­ter­est­ing place to start, since they are un­likely to re­sem­ble any­thing that comes to mind when you think of a ra­di­a­tor; how­ever, as the con­duit be­tween the header tanks and the ac­tual core of the ra­di­a­tor, they are

New Zealand Classic Car - - Technical Feature -

1. The header plates be­gin life as sheets of brass, which are cut to the right size ac­cord­ing to the ra­di­a­tor’s spec­i­fi­ca­tions. A job sheet will spec­ify the num­ber of rows re­quired, as well as the ra­dius of the cor­ners. 2. The brass sheets, hav­ing been cut to the cor­rect di­men­sions, are pressed for what are known as ‘pierc­ings’ — holes through which the coolant will flow. The die used in the press is cho­sen to suit the ra­di­a­tor-core re­quire­ments. From here, the brass sheet, with fresh pierc­ings, is brought to have its cor­ners cut to the ap­pro­pri­ate ra­dius. 3. The header plate is then brought to the ra­dius-form­ing press, where it will meet with one of a num­ber of dif­fer­ent ra­dius dies, de­pend­ing on the cor­ner ra­dius re­quired. The process es­sen­tially gives the header plate a folded edge, along both the flat edges and the cor­ner radii. 4. The com­pleted header plate is ready to be at­tached to the rest of the core, the as­sem­bly of which is cov­ered next. Th­ese can be made with dif­fer­ent mount­ings, in­clud­ing bolt-on, weld-on, or with castel­lated edges that lock into place in plas­tic header tanks, sealed by a rubber O-ring. Adrad car­ries a range of header tanks for a va­ri­ety of ap­pli­ca­tions, from plas­tic header tanks for daily-driv­ers through to bolt-on brass tanks for a Ken­worth truck.

The first step in pro­duc­ing the ac­tual core of the ra­di­a­tor in­volves the ‘CT fin ma­chine’, which is fed a large spool of cop­per that will even­tu­ally form the fins. The ma­chine stamps the cop­per to achieve the ac­cor­dion-like zig-zag shape, and punches lou­vres in it if re­quired, be­fore com­press­ing the length to an ap­pro­pri­ate finsper-cen­time­tre mea­sure­ment. All of this is pre­pro­grammed into the ma­chine ac­cord­ing to the ra­di­a­tor be­ing as­sem­bled, with each as­pect of the pro­ce­dure im­por­tant in its own way. 1. The num­ber of fins per cen­time­tre is cal­cu­lated based on the broader pic­ture of the ra­di­a­tor’s ap­pli­ca­tion. If it is to be a nar­row-core ra­di­a­tor, the con­vec­tion ef­fect could be en­hanced with a nar­rower pitch, whereas a thicker core would func­tion bet­ter with a more open pitch — “Hav­ing too tight of a fins-per-inch on a thick-core ra­di­a­tor would be like hit­ting a brick wall — not good for air flow,” ex­plained Tara Maylin, Adrad’s New Zealand man­ager. Lou­vred fins are su­perb for most road-go­ing ve­hi­cles, with en­hanced cool­ing ca­pa­bil­i­ties, but would not be used in cer­tain ap­pli­ca­tions. “On a hay-baler or ma­chin­ery work­ing in lime works, for ex­am­ple, it’s likely that lou­vres will not be stamped, and will have a more open pitch, due to the like­li­hood of seeds or for­eign mat­ter be­ing lodged be­tween the fins,” Tara said. Such ra­di­a­tors also use a tubu­larstyle core, rather than the CT cores shown here, and the de­sign will make it eas­ier to wa­terblast or man­u­ally clean the ra­di­a­tor core with­out dam­ag­ing the fins. 2. Once the cop­per fins have been pro­duced, they are ar­ranged into what be­gins to re­sem­ble a ra­di­a­tor core. The tubes through which the coolant is chan­nelled are brass that has been coated with sol­der — the sol­der coat­ing will melt and fuse the fins with the tubes when the core is baked in a spe­cial oven. At this stage, the core can still be touched up cos­met­i­cally if it needs to look per­fect, though aes­thetic blem­ishes don’t ad­versely af­fect per­for­mance. Once the core has been baked, it stays as-is. 3. The fins and tubes are stacked al­ter­nately un­til the ra­di­a­tor-core spec­i­fi­ca­tions are met, with gal­va­nized side plates on the top and bot­tom edges. A roll of sol­der is also ap­plied be­tween the gal­va­nized side plates and top and bot­tom fins, as well as be­tween the next row of fins — this is for ad­he­sion, as stated in Step 2, since the up­per­most and low­er­most rows are most sus­cep­ti­ble to dam­age from flex or pres­sure. 4. At this stage, the rows are stacked loosely, and the core as­sem­bly is clamped to­gether from top to bot­tom to achieve the spec­i­fied core height. Once the height has been achieved, the core as­sem­bly is held in place within a bak­ing frame. 5. With the ra­di­a­tor core within the bak­ing frame, the header plates can be ap­plied. As de­scribed in the pre­vi­ous sec­tion, th­ese are man­u­fac­tured con­cur­rently in a dif­fer­ent part of the fac­tory known as the ‘press shop’. 6. The header plates will even­tu­ally be con­nected to the header tanks — whether by weld­ing, bolt­ing, or lock­ing tabs in plas­tic-tank ap­pli­ca­tions. With the header plates in place on ei­ther side of the core and the ends of the tubes pro­trud­ing through, the tube ends are flared to in­crease the wa­ter-chan­nel open­ings for op­ti­mized fluid flow.

THE CORE

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