De-ionized (DI) or reverse osmosis (RO) water is recommended to make up the flux slurries. This is to avoid long-term accumulation of mineral deposits in the flux delivery system that can cause blockage of nozzles and/or inadvertently drop on the heat exchanger. Furthermore, local plant or city water may contain ppm levels of contaminants such […]
Selective Pre-Fluxing with Adhesives – Fashion or Progress Summary Over the last 15 years, selective pre-fluxing – also called paint fluxing or binder-based fluxing – has evolved as an alternative method for applying flux powder in aluminium brazing industry. There are many activities to define process parameters of fluxing with adhesives. The first part of […]
Preparation In the simplest operation, the lid is removed and flux is manually scooped out of the drum (with a large plastic scoop) and added to the flux slurry reservoir tank. The flux should always be added to water and never scooped into an empty tank. Aerosolization should be controlled by a local exhaust ventilation […]
Selective Pre-Fluxing with Adhesives – Fashion or Progress Summary Over the last 15 years, selective pre-fluxing – also called paint fluxing or binder-based fluxing – has evolved as an alternative method for applying flux powder in aluminium brazing industry. There are many activities to define process parameters of fluxing with adhesives. The first part of this […]
This technique, also known as dry fluxing is gaining popularity as an alternative fluxing practice and therefore will be described here in some detail. Dry fluxing is a technology whereby the flux is electrostatically charged and applied to a grounded work piece, in our case a heat exchanger or individual heat exchanger components. The electrostatic […]
Considerations Fixtures are used to hold the braze assembly in place during brazing. Surfaces with molten filler metal are very “greasy” and the fixtures need to hold the shape and tolerances during heat-up. Fixtures may also be used to support attachments such as inlet or outlet tubes. When considering the type or configuration of fixtures […]
Sample Preparation – Orientation The heat exchanger chosen for the purpose is a NOCOLOK Flux brazed radiator. To provide some orientation as to where the metallographic sections will be taken from, Figure 1 shows the water-side header area (top) and part of the finpack, sidesupport and header area. In most metallographic investigations of brazed heat exchangers, the […]
Article from the Newsletter of our sponsor Solvay Fluor: New glass brazing furnace in the NOCOLOK Technical Center Many visitors to seminars, trade shows or videos are already familiar with the test glass brazing furnace in the NOCOLOK Technical Center. The unique furnace now has a big brother. All components of the new test furnace, […]
Case Study A radiator core retrieved from service was examined for a suspected premature corrosion related failure. Upon closer metallographic examination, no evidence of corrosion was found at the failed area. Header: AA4343/ AA3005 Tube: AA4343/ AA3003 It was concluded that the cause of the failure was […]
Experimental The effect of temperature on filler metal erosion was studied using an automotive radiator core. In this case, joining progresses initially as expected. The cladding layer on the tube melts and flows by capillary action to the fin to tube joint and a normal fillet forms. However, as the peak brazing temperature is allowed […]