Aluminium brazing
Creating bonds that endure
Heat exchangers can be found in wide-ranging situations in which the transfer of thermal energy plays a decisive role. The manufacture of heat exchangers predominantly relies on aluminium brazing materials. These are advanced, high-quality, multi-layered composites made from a core alloy clad on one or both sides with an AlSi brazing alloy. AMAG has produced these composites for over 40 years using a sophisticated roll cladding technology. This solid-state pressure welding process produces a tight metallurgical bond between the brazing solder and the core bars, which facilitates outstanding soldering results in downstream processing of the material.
The resulting composite materials can be tailored in terms of their strength, weight, heat conductivity, formability and corrosion resistance. Since the first issue of AluReport was published in 2008, AMAG’s activities in relation to brazed products have grown considerably. The company has tripled its turnover in this segment over this period, increasing its customer base by over 40%. This growth has been made possible by constant expansion of AMAG’s alloy portfolio. With a product portfolio now comprising seven long-life alloys (AMAG TopClad® LL) and nine brazing alloys, AMAG now offers twice as many materials as it did 15 years ago. Some of the key drivers of these product developments are the demand for higher-strength brazed materials from heat exchanger manufacturers seeking to reduce product thicknesses, increased expectations from OEMs in relation to crash-resistance, and additional demands regarding corrosion resistance.In an effort to satisfy these increased customer requirements, AMAG launched its multi-layer solutions in which several functional, tailored layers can be plated on top of each other. These four-layer and five-layer systems can optimize the characteristics of the resulting products to push the limitations of conventional heat exchanger materials following either controlled atmosphere brazing (CAB) or vacuum brazing (VB). In fact, 6xxx alloys - which are not typically used without additional diffusion barriers to prevent magnesium diffusion during brazing using the CAB process - can also be used in a multi-layer solution produced using CAB. This makes it possible to significantly increase the post-brazing strength of materials in heat exchangers compared to the 3xxx alloys used as standard in the CAB process.
AMAG responded to the increased interest in flux-free, brazable materials by intensifying its research activities. This led to the successful development of an aluminium composite material that facilitates flux-free brazing using the CAB process. A sophisticated combination of a modified brazing alloy and innovative processing makes it possible to disrupt the oxide layer in the brazing process, even when using nitrogen. This allows the brazing filler to flow freely and therefore achieves strong bonding.
| AMAG TopClad® non-heat-treatable alloys | AMAG TopClad® HS heat-treatable alloys | AMAG TopClad® UHS heat-treatable alloys | AMAG TopClad® LL long-life alloys |
|---|---|---|---|
| 3003 | 6060 | 7020 | LL 93003 |
| 3004 | 6063 | LL 93005 | |
| 3005 | 6951 | LL 93009* | |
| 3103 | LL 93503 | ||
| 3105 | LL 93505 | ||
| LL 93507* | |||
| LL 93535 |
| VB filler alloys | CAB filler alloys | Zinc-containing filler alloys | Interliner alloys |
|---|---|---|---|
| 4004 | 4343 | 40143 | 1050 A |
| 4104 | 4045 | 40145 | 7072 |
| 40141* | 4047 | 10150* | |
| 40245* |
When it comes to vacuum brazing, AMAG has over 20 years of expertise, possesses the ability to pickle materials on an industrial scale and offers modified brazing materials, making the company an ideal partner for optimal soldering and brazing of components in vacuum-brazed coolers. By investing in a new coil coating line, AMAG has also ensured its ability to implement additional pickling steps during future production processing, thereby facilitating the manufacture of heat exchanger materials with extremely clean surfaces. Pickled products like AMAG PURE® deliver significant benefits for customers through their positive impact on brazing results.
On the process side, customers’ pursuit of stable brazing and lower reject rates have fueled the company’s efforts to expand its portfolio of modified brazing materials. AMAG brazing materials 40141 and 40245 are prime examples of this.
These numerous product developments have led AMAG - often termed a “niche” supplier in the past, with a portfolio primarily geared toward vacuum brazing - to become a market-leading full-range supplier. By serving the industrial heat exchanger, agricultural machinery, construction machinery, wind power and automotive markets, AMAG is exceptionally well diversified. In fact, the company has recorded strong growth in each of these markets since 2008. Significant growth has been recorded in relation to industrial cooling construction for the LNG liquefaction, petrochemical and air separation segments as well as in the automotive supplier sector for components in engine and transmission oil cooling units, intercoolers, coolant coolers, capacitors, chillers and battery cooling systems. AMAG is particularly well positioned in the battery cooling segment, which relies on wide coils and sheets in thicknesses of 0.4-2.0 mm.
The geographical scope of AMAG’s activities has also changed considerably in recent years. While the North American market played a relatively minor role 15 years ago, it now accounts for 25% of the company’s turnover in this segment. In light of this extraordinary growth, AMAG offers customized logistics processes tailored to each customer’s needs. We have also significantly intensified and expanded the on-site customer support provided by our technology and sales specialists.
After commissioning additional rolling mills in 2014 (hot rolling mill) and 2017 (cold rolling mill), AMAG now has two fully independent facilities on the same premises, which ensures it has fully redundant systems for hot rolling, cold rolling and cladding processes. This means that the company can select the optimal process route for specific customer requirements. With a maximum width of 2,050 mm for clad sheets and coils, this modern infrastructure now offers AMAG a unique opportunity to efficiently process products with widths of 600-1,000 mm, which previously proved awkward in some circumstances. With its wide portfolio of core and cladding materials, combined with its modern plant and machinery, AMAG soon secured a number of high-volume platforms.
AL4®ever brazing products
When it comes to the dominant market issues, the rapid rise in the significance of sustainability is one of the most crucial changes in recent years. As a recycling expert, AMAG has long played a pioneering role in this space. All the same, carbon footprint calculations were hardly a topic of conversation when the first AluReport issue was published in 2008. Today, such calculations have become standard practice at AMAG and are certified by independent external bodies. It is a stated goal of AMAG to reduce the carbon footprint of existing and newly developed alloys through collaboration with its customers. AMAG is already able to offer its customers CO2-optimized braze-clad products in its AL4®ever product line. It plans to launch two new long-life alloys in 2024, providing an optimal balance between a reduced carbon footprint and maximum customer benefits in terms of the materials’ brazability, strength and corrosion resistance.
AMAG considers itself a full-range supplier, covering the entire spectrum of brazed materials in thicknesses from 0.4-8 mm and offering controlled atmosphere brazing (CAB), vacuum brazing (VB) and flux-free brazing methods. This fundamental strategic focus will not change in the future. Through continued innovation and investment in research and development, AMAG is consolidating its position as a leading supplier of brazed aluminium products, thereby ensuring it will remain a dependable partner to its customers in the future.
