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 […]
The European Association for Brazing and soldering — EABS for short — together with experts from Solvay Fluor, holds technical training seminars in which the theory and practice of flame and furnace aluminium brazing are communicated in detail. 40 interested participants from all over the world gather for the two day seminar in Hannover, Germany: […]
HF can potentially be formed during the flux brazing process. HF is very toxic, irritating to the eyes, skin and respiratory tract and cause severe burns of the skin and eyes. The threshold limit value (TLV) for HF is a ceiling concentration of 3 ppm (2.3 mg/m3), a concentration that should not be exceeded during […]
How to obtain? A lot of information can be gained from heat exchanger brazing cycle temperature profile. It is probably one of the most important pieces of information that the brazing engineer can use to fully understand his process. A temperature profile will provide information such as heating rate, maximum peak brazing temperature, time at […]
Furnace atmosphere The recommended furnace atmosphere conditions necessary for good brazing are as follows: Dew point: ≤ -40°C Oxygen: < 100 ppm Inert gas: nitrogen The most common source of nitrogen is that generated from liquid nitrogen storage tanks. A typical nitrogen gas specification from a liquid source indicates that the moisture content is <1.5 […]