Hartlöten vs Schweißen: Metallverbindung für Präzision und Langlebigkeit

 

Metal joining plays a crucial role in various industries, from automotive to aerospace. Different techniques, such as brazing, welding, and soldering, are utilised based on the requirements of the specific application. Among these methods, brazing and welding are frequently compared due to their common use in creating strong metal joints. But what sets brazing apart from welding, and how do the benefits of these processes compare? In this article, we will delve into the key differences, advantages, and best use cases for both brazing and welding, helping you decide which method best suits your metal joining needs.

 

 

How Brazing Works

Brazing is a process that joins metals by heating a filler metal to a temperature below the melting point of the base metals, allowing the filler to flow into the joint by capillary action. The critical distinction between brazing and welding lies in the temperature. While welding melts both the filler and base metals, brazing only melts the filler metal, leaving the base metals intact. The process typically occurs at temperatures between 620°C and 870°C (1150°F to 1600°F), much lower than those needed for welding.

The filler metal used in brazing forms a metallurgical bond with the surfaces of the base metals, which are heated but not melted. This bond is achieved as the filler metal is drawn through the joint, ensuring a consistent, reliable connection. Brazing is often used in applications requiring high precision and minimal thermal distortion, including HVAC systems, electronics, automotive parts, and delicate components in aerospace.

 

 

Advantages of Brazing

One of the main advantages of brazing is its ability to create strong joints without melting the base metals. This retains the metal’s original properties and reduces the risk of distortion or warping that can occur at higher temperatures. As the base metals are not melted, their structural integrity remains intact, making brazing ideal for applications where maintaining these characteristics is essential.

Brazing is also highly versatile when it comes to joining dissimilar metals, such as steel to copper. Since the base metals do not need to be melted, you can choose metals that suit your assembly’s functional requirements without worrying about their melting points. This flexibility makes brazing an attractive option for engineers who need to join materials like tungsten carbide, ceramics, and graphite with metals like aluminium or steel.

Another benefit of brazing is its aesthetically pleasing results. Brazed joints typically form smooth, precise fillets, making them ideal for applications where the appearance of the joint is important. The neatness of brazed joints can also eliminate the need for finishing work, leading to time and cost savings.

Brazing is relatively easy to learn compared to welding. While welding requires precise timing in applying heat and filler metal, brazing relies more on the natural action of capillarity to distribute the filler metal. This makes the process easier to automate, especially in high-volume production environments.

 

 

How Welding Works

In contrast to brazing, welding involves melting both the filler metal and the base metals to create a joint. This fusion process results in strong connections, often as strong as or even stronger than the original metals. Welding is typically performed at much higher temperatures than brazing, starting at the melting point of the base metals, which can range from 1083°C (1981°F) for copper to 1370°C (2500°F) for steel.

Welding is the preferred method when thick sections of metal need to be joined, especially in applications like structural steelwork, heavy machinery, and construction. Common industries that rely on welding include transportation, aerospace, and manufacturing. For instance, welding is frequently used in the construction of bridges, pipelines, and aircraft, where strength and durability are critical.

 

 

Advantages of Welding

Welding offers several key advantages, particularly when it comes to creating strong, durable joints. The high temperatures used in welding ensure that the base metals fuse, providing a robust connection that can withstand high loads, stresses, and environmental conditions.

In certain scenarios, welding can be more cost-effective than brazing due to its ability to create single-point joints quickly. For example, electrical resistance welding can rapidly join two thin metal strips at a specific point, offering a fast and inexpensive solution for high-volume production. However, linear joints, where heat is applied along a seam, may pose challenges, such as warping or thermal stress on the base metals.

Despite its strength, welding can introduce complexities when joining dissimilar metals. Since both metals must be melted, their different melting points can make it difficult to achieve a stable joint without specialised techniques or equipment.

Automating welding can also be more challenging than automating brazing. Welding requires precise control of heat and filler material, particularly for linear joints. Advanced welding processes, such as friction welding or electron beam welding, can automate complex joints, but these methods often require expensive machinery and are better suited for large-scale production runs.

 

 

Key Differences Between Brazing and Welding

When choosing between brazing and welding, several factors should be considered:

1. Temperatur: Brazing occurs at lower temperatures, preserving the base metals’ properties and reducing the risk of thermal distortion. Welding requires high temperatures that melt the base metals, creating strong but sometimes distorted joints.
2. Joint Aesthetics: Brazing produces smooth, clean joints that often require no finishing, while welding can leave behind uneven beads that may need additional processing.
3. Ease of Use and Automation: Brazing is easier to automate and learn than welding, making it a preferred choice for high-volume production of smaller, more precise assemblies. Welding, however, is more challenging to automate, particularly for linear joints.
4. Dissimilar Metals: Brazing is better suited for joining dissimilar metals, as the base metals do not need to be melted. Welding dissimilar metals can be more complex and may require advanced techniques to ensure a stable joint.
5. Application Areas: Brazing is ideal for delicate, high-precision components such as electronics, HVAC systems, and jewellery. Welding is preferred for larger, structural applications like bridges, pipelines, and heavy machinery.

 

Choosing the Right Method for Your Application

When determining the best metal joining technique for your project, several factors come into play. If you need to join metals with different melting points or are working on assemblies that require precision and minimal distortion, brazing is often the best choice. The ability to create strong, reliable joints without melting the base metals ensures that the original properties of the metals are maintained.

Welding, on the other hand, is the go-to method when strength and durability are paramount. For thick sections of metal or large structural assemblies, welding provides the robust joints necessary to withstand heavy loads and harsh conditions.

Other factors to consider include the thickness of the base metals, the need for spot or line joints, and the desired appearance of the final assembly. In some cases, alternatives like mechanical fastening or adhesive bonding may be sufficient, but these methods rarely match the strength and durability of brazed or welded joints.

 

 

Other Metal Joining Methods

In addition to brazing and welding, there are other techniques available for metal joining. However, options like mechanical fastening (riveting, staking, threading) often fall short in terms of strength and leak-tightness. While providing permanent joints, adhesive bonding and soldering do not typically offer the same strength or temperature resistance as brazing or welding.

 

 

 

 

 

Both brazing and welding have their place in modern metalworking, each offering unique advantages depending on the application. While welding is often favoured for its strength and durability in large-scale industrial projects, brazing excels in precision, ease of automation, and the ability to join dissimilar metals.

At Fusion Europe, we specialise in high-quality brazing solutions that provide both precision and reliability. Our range of brazing pastes and products are designed to meet the diverse needs of various industries. Whether you’re working in electrical, automotive, or aerospace, we have the right solution for your metal joining needs. Contact us today to learn more about our brazing options and find the best fit for your next project.