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CAB Brazing Conference & Seminar
The CAB Seminar is presented every other year for industry professionals to present the latest improvements in CAB technology and provide basic, practical information for companies new to the CAB Process.When switching from copper to aluminum brazing our customers have told us that this event saves the both time and money by shortening the learning curve and staying updated on best practices. Click here for attendee comments on the May 2009 event. Next dates to be announced.
AHR Update: Mike Jacobs will present "CAB Equipment for HVAC - The Latest in Controlled Atmosphere Brazing furnace systems for brazing HVAC aluminum condensers" on Monday, January 25, Theater B at 3:30 PM - Click on the button above for your free registration, travel and hotel information or email Mike direct at mjacobs@secowarwick.com -
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2009 Technical Program
CAB Brazing for HVAC CAB Furnace Designs
Principles of CAB Brazing Practical Heat Transfer Alloy Selection & Properties - SAPA Heat Transfer Heating Systems Flux , Issues & new Technology - Dr. Leszek Orman Temperature Control New Developments in CAB equipment Flux Application Microchannel Technology - Fin Machine Co. Atmosphere Control Dry Off Ovens Thermal Degreasing Furnace Maintenance Need Answers Today? Visit Aluminum Brazing Maintenance Tips
2009 FAQs
Changing from Copper to Aluminum | Nitrogen Flow | Paint Fluxing | Profiling | Element Design
Dr. Hawksworth - Question: Can aluminum and copper be run through the same equipment for the production of CAB radiators?
RESPONSE:
This is not a good idea and would not be recommended for two main reasons:
- Copper depresses the melting point of the aluminum-silicon system and any contamination of the aluminum surface with copper particles could cause localized melting and burn through in those areas during brazing.
- Copper is electropositive with respect to aluminum, and areas alloyed with copper contamination that do not “burn-through” during brazing will set up localized galvanic cells with unalloyed aluminum. This would promote rapid galvanic corrosion in a corrosive environment compromising the durability of the heat exchanger.
If copper and aluminum have to run on the same tooling it would be advisable to run the aluminum first. Machinery and tooling would have to be thoroughly cleaned and all possible sources of copper contamination should be eliminated. These would include pick up on guide rolls, fines and dust, scarf on cutting edges, contaminated lubricant (in the sump), and even contamination that could be transferred from personal protective clothing such as metal working gloves.
Dr. Orman - Question: Nitrogen flow - what should it be?
RESPONSE: Commonly used values of the nitrogen pressure are about 6 to 7 bars for the distributing network. Then the pressure is reduced usually with two pressure reducers to a value in the range 1,5 to 3 bars and blown in purge nozzles to the furnace muffle. Please treat these numbers as indicators only since they can differ from furnace to furnace and from design to design. The real value which should be of interest to a brazing engineer is the actual volume of the nitrogen is purged into the furnace chamber. This is measured by flow meters. Each furnace must be equipped with a set of flow meters preferably one flow meter for each purging nozzles and one main flow meter. The nozzles should be set in such a way that nitrogen is mainly fed into the furnace in the area of the brazing zone from where it should flow towards both ends of the furnace. Some nitrogen should be purged into the cooling chambers and very little at the furnace inlet.
Link to SECO/WARWICK Maintenance Tip on Nitrogen Adjustment in Active Only CAB Brazing furnaces, by Joe Reitinger, SECO/WARIWCK Field Service Engineer
Andrzej Bielewicz, SECO/WARWICK- Question: Why Paint Fluxing?
RESPONSE: A Flux-Painting system improves the brazing process and decreases the number of leaks on the core due to better application of flux on the headers and manifolds. In some designs of heat exchangers, the connection between tube and header/manifold is critical, and requires more flux on the joint (tube-manifold/header connection). This method enables flux to be applied on the surfaces which are inaccessible after the assembly of heat exchanger e.g. all oil cooler plates;therefore it has become standard in brazing oil coolers.
The advantage of the flux painting is that application of additional amounts of flux to headers and manifolds during final fluxing is not required, as compared with using a spray Wet Fluxer with only one concentration for whole heat exchanger. The flux painting process will provide less flux consumption and less time needed for flux application.
Generally the automatic paint fluxing machine is capable of applying flux with a binder on heat exchanger parts (manifolds/headers) prior to assembly. The presence of a binder allows for the pre-fluxed parts to be assembled without the risk of removing the applied flux layer.
Chuck Field, SECO/WARWICK - Question: Do you provide a system for checking profiles?
RESPONSE: We use Datapaq
Link to SECO/WARWICK Article Database: "The CAB profiling system as a Quality Control Tool" a guest article provided with permission from Datapaq Inc. USA, originally published in HEAT PROCESSING Magazine (Germany), (4) issue 2 2006
Datapaq website, http://www.datapaq.com/
Dan Maloney, SECO/WARWICK - Question: What is the difference between bayonet and sinuous loop elements?
RESPONSE: SECO/WARWICK can provide both types of heating systems. Each design has strengths and weakness, read the table below for a comparison; Understand that the primary strength of any electrical heating element is proper design:
Bayonet
Can be changed while furnace is hot
Lower cost
Lower cost, replace elements without shutting down system
Sinuous Loop
Furnace must be cold, roof must be removed Additional 14% in capital cost Does not require alloy tubes for support, longer service life * Based on recent estimate
Note: Maintenance and operation have a major impact on element life
When asked what they like best about this program, attendees responded:
“Totality of information presented”
“All the speakers have a lot of experience in CAB Brazing Process & Equipment”
“More details about furnace related topics (were) presented…Good job! Well Done!”
“Videos, all the technical sections”
“Dr. Orman’s presentation, Maintenance presentation by Chuck. The whole seminar was excellent.”
Controlled Atmosphere Aluminum Brazing (CAB) Process Background
CAB Brazing is used in both automotive and HVAC manufacturing for brazing radiators, condensers, oil coolers, evaporators, heaters and charge air coolers. NOKOLOK© Brazing was originally developed by Alcan as a non-corrosive flux brazing process for heat exchangers.
Today, NOCOLOK is the trademark for Solvay Fluor GmbH flux products, but remains the common name for the CAB process.
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