Vacuum Brazing Oven

Vacuum brazing oven is a high-precision heat treatment equipment widely used in various fields, such as aviation, national defense, electronics, medical and other industries. It can efficiently braze metal parts, achieving very high machining accuracy and strength.

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Product Introduction

What is Vacuum Brazing Oven?

The vacuum brazing oven can process not only conventional steel but also various metal materials such as gold, silver, copper, and aluminum, making it highly favored by engineers. The advantages of the vacuum brazing oven not only lie in its high efficiency, high precision, and good processing effect but also in its environmental friendliness. The brazing furnace will not produce irritating gases or pollutants during processing and will not have adverse effects on the environment or human health.

Equipment working conditions

1. Power conditions: three-phase 380V (±6%); 50Hz

2. Cooling water requirements: inlet pressure 0.1～0.2MPa; temperature ≤30℃; PH value is about 7; water quality is soft water without sediment and impurities; flow rate 40T/h.

3. Environmental conditions: Ambient temperature: higher than 0°C~35°C; ambient relative humidity ≤95% (25°C); altitude below 1000m;

4. Compressed air (power air source): pressure 0.4～0.6MPa

5. Installation method: ground installation

Main data parameters of vacuum aluminum brazing furnace
Model	Average temperature zone size	Maximum temperature	Ultimate pressure	Pressure rise rate	Temperature uniformity
RVSL-459	450×450×900	850	8.0×10-4	0.5	±3
RVSL-669	600×600×900	850	8.0×10-4	0.5	±3
RVSL-6612	600×600×1100	850	8.0×10-4	0.5	±3
RVSL-8716	800×700×1600	850	8.0×10-4	0.5	±3
RVSL-7112	700×1000×1200	850	8.0×10-4	0.5	±3
RVSL-7114	700×1000×1400	850	8.0×10-4	0.5	±3
RVSL-1325	1300×1100×2500	850	8.0×10-4	0.5	±3

Principle Operation of Vacuum Brazing Furnace

The vacuum brazing furnace is primarily designed for synthesizing or welding precision instruments, such as aerospace equipment, especially engines. In vacuum brazing, the entire workpiece is heated uniformly under vacuum conditions, allowing precise temperature control and minimal workpiece deformation. This method enables the brazing of high-temperature alloy materials without the use of soldering flux, resulting in high-quality brazing joints. Vacuum brazing furnaces consist of a vacuum system and a heating system. The vacuum system ensures the required vacuum level for the brazing process, while the heating system heats the parts and melts the solder, enabling the soldering of the parts. The entire process is automatically controlled by the temperature controller.

Features of Vacuum Brazing Furnaces

High strength joints in heat treatable aluminium alloys that enable light weight heat exchangers to be manufactured with superior structural integrity;
Fluxless brazing meaning no potentially harmful residues or contaminates;

Excellent conductivity, both thermal and electrical, providing exceptional heat rejection characteristics while maintaining electrical integrity;
Greater freedom in design of products with intricate internal fluid passages or thin wall applications;

Greater reliability and durability in high stress design application compared to bolted or adhesive bonded applications;
Relatively low-cost solutions for high end designs.

Benefits of Vacuum Brazing Furnace

Exceptional Quality and Uniformity

In vacuum furnace brazing, the absence of air and the controlled environment prevent oxidation and contamination, leading to cleaner and stronger joints.

Uniform heat distribution ensures consistent brazing quality across the entire piece, which is crucial for complex assemblies and high-precision components.

Enhanced Strength and Durability

Joints created by a brazing vacuum furnace are notably stronger due to the even distribution of brazing filler, reducing weak spots.

This method enhances the product's lifespan, offering better resistance to thermal and mechanical stresses.

Cost-Effective and Efficient

The vacuum furnace brazing process reduces material waste and energy consumption, which leads to significant cost savings.

Minimizes the need for post-brazing treatments, further reducing production time and costs.

Eco-Friendly Approach

Generates fewer emissions and requires less energy, aligning with sustainable manufacturing practices.

Helps industries meet environmental regulations and reduce their carbon footprint.

Versatility in Applications

Suitable for various metals and alloys, vacuum brazing applications extend across many sectors, including aerospace, automotive and medical devices.

Allows for joining dissimilar materials, offering greater design flexibility and innovation in product development.

Precision and Control

The ability to precisely control temperature and environment in vacuum brazing allows for intricate and delicate metal joining, which is essential in high-precision industries.

Ensures minimal distortion and shrinkage, crucial for maintaining dimensional accuracy in complex components.

Process Details of Furnace Brazing

Furnace brazing is a semi-automated process by which metal components are joined using a dissimilar lower filler metal. Furnace brazing allows design and manufacturing engineers to join simple or complex designs of one joint or multi-joint assemblies.

One of the most common forms of furnace brazing is accomplished in a vacuum furnace and referred to as vacuum brazing. Parts to be joined are cleaned, brazing filler metal applied to the surfaces to be joined, then placed into the furnace. The entire assembly is brought to brazing temperature, after the furnace has been evacuated of air, to eliminate any oxidation or contamination occurring as the braze filler metal melts and flows into the joints.

Furnace brazing offers the flexibility to join a wide range of metals such as nickel based alloys, stainless steels, carbon and alloy steels. Other non-ferrous materials can also be brazed including aluminium, titanium and copper.

The materials being joined dictate the type of atmosphere in which the assembly is heated to join its components. In addition to vacuum, protective or reactive atmospheres include hydrogen, nitrogen, a blend of hydrogen and other inert gases, exothermic and endothermic gas, as well as argon, and helium.

Furnace brazing is the process by which metal components are joined using a dissimilar lower melting filler metal.

Furnace brazing is accomplished using a variety of techniques. They include different furnace designs, which include batch as well as continuous furnaces.

Furnace types used for brazing, include:

● Vacuum

●Controlled atmosphere

●Continuous/mesh belt

●Reducing atmosphere

The service is used to manufacture assemblies with one joint or multiple joints using a dissimilar lower melting filler metal.

Vacuum Brazing Materials

With regards to materials we focus on the joining of reactive materials with the vacuum brazing process or materials where oxides are a priority to remove during the brazing process:

● Exotic base metals such as Aluminum, Titanium, Zirconium, Niobium, Molybdenum, and Tantalum

● Nickel and Iron-based alloys containing aluminum and/or titanium

● Refractory metals

● Reactive metals

● Ceramics & metal to ceramics

● Beryllium

Applications of Vacuum Brazing

There are manufactured assemblies that require brazing in almost any industry you can think of. Some common applications include:

● Honeycomb Brazing

● Heat Exchangers

● Igniters

● Pressure Vessels

● Turbine Engine Components

● Hydraulic Fittings & Manifolds

Company profile:

Shenyang Hengjin, established in 2000, is a technology-based joint-stock enterprise specializing in the research, development and manufacture of vacuum equipment. The company is located in a national development zone, has independent intellectual property rights, and is a national high-tech enterprise. Has 28 patents and various enterprise honor certifications.

FAQ

Q: 1. When are refractory metals joined with vacuum brazing?

A: They are vacuum brazed when joining them to reactive metals due to the reactive metal's oxidation or intrinsic contamination; titanium to aluminum for example. Refractory metals are the classification of metals that demonstrate very high melting temperatures, up to 3410° for Tungsten, which is more than double of Titanium. Refractory metals all share high corrosion and abrasion/wear resistance and excellent thermal and mechanical strength properties. Although there are twelve in this class of metals, only five are widely used: Tungsten, Molybdenum, Niobium, Tantalum, and Rhenium.

Q: 2. What are and why are reactive metals a perfect fit for vacuum brazing?

A: Reactive metals are a group of metals that chemically react with exposure to air, water, acids, and mineral acids. With regards to material joining and brazing, these reactions can create surface oxides or present contamination during the brazing process which can cause a plethora of issues resulting in an unsuccessful braze-joint; vacuum brazing is the preferred process for this reason. For example, aluminum will react with air very quickly, producing undesirable surface oxides that require chemical cleaning to remove and then sealing in bags prior to the vacuum brazing process.

Q: 3. What is vacuum brazing?

A: Vacuum Brazing is a process that creates high quality joints under temperatures from about 800°C to 1150°C in a vacuum atmosphere. This also allows for the joining of different materials like for example ceramic to steel.

Q: 4. What is the difference between welding and vacuum brazing?

A: The main difference between these technologies is that the base material is melted during the welding process, whereas during brazing only the brazing alloy melts while the base material itself remains solid.

Q: 5. What is the vacuum level for brazing?

A: Vacuum plus high temperature results in decomposing oxide layers. The brazing process consists of a pump down to 10-3 mbar and heating in different steps; vacuum is maintained below 10-4 mbar during heating. Historically, oil-sealed pumps and diffusion pumps are used in the brazing process.

Q: 6. What is the temperature of a vacuum brazing furnace?

A: Vacuum brazing is usually a high temperature (typically 1700°F/927°C - 2250°F/1232°C), fluxless process using nickel-base, pure copper and less frequently precious BFM. There are several advantages to brazing under vacuum conditions: The purity level of the atmosphere (vacuum) can be precisely controlled.

Q: 7. What materials are used in vacuum brazing?

A: The vacuum technology allows to braze a wide range of materials, from single structural steels to high-alloy cold and hot work steels, to super alloys, as well as non-ferrous metals such as copper and titanium and even ceramics, hard metals, and the cutting materials cBN and diamonds.

Q: 8. What is a vacuum brazing furnace?

A: Vacuum Brazing is a fluxless brazing process that is performed under high vacuum in a heated chamber using pre-placed clad filler material.

Q: 9. Why use brazing instead of welding?

A: The first big difference is in temperature – brazing does not melt the base metals. This means that brazing temperatures are invariably lower than the melting points of the base metals. Brazing temperatures are also significantly lower than welding temperatures for the same base metals, using less energy.

Q: 10. What are the two types of brazing?

A: There are four main types of brazing heating methods: torch or manual brazing, induction brazing, resistance brazing, and vacuum brazing. The heating method most commonly used in brazing a single assembly is the hand held torch.

Q: 11. How do you prepare for vacuum brazing?

A: The first step in the vacuum furnace brazing process is to thoroughly clean the parts to be joined. This ensures that there are no contaminants (such as oil, grease, or oxides) that could interfere with the brazing process.

Q: 12. Can brazing be performed in a vacuum?

A: Vacuum brazing is a manufacturing process that joins together components (called parent components) using a filler metal called a brazing alloy. It may involve joining together metal-to-metal components or two dissimilar materials, such as ceramic to metal.

Q: 13. What temperature is aluminum vacuum brazing?

A: This furnace profile is known within the industry as a vacuum brazing "recipe." The recipe specifies the temperature, vacuum level, and cycle time. Brazing of cold plates and heat exchangers usually takes place at approximately 1100°F (593°C) and a vacuum level between 5 to 6 Torr.

Q: 14. What is the introduction of vacuum brazing?

A: Brazing is a method of joining two or more metals by melting a filler metal, or the brazing alloy. When alloys are used instead of a pure metal for the process in a vacuum furnace, they do not contain fluxes, there is therefore no need to remove the slag by mechanical methods and the weld appears clean.

Q: 15. What gas is used for brazing?

A: For brazing there are generally two equipment options to choose from: oxygen/acetylene or air/acetylene. While alternate fuel gases are available, most contractors still use acetylene.

Q: 16. Why use a vacuum furnace?

A: Vacuum furnaces are used in many applications in all industries. A vacuum is one of the methods to protect heated steel and metal parts from the negative influence of an air atmosphere.

Q: 17. How does a vacuum furnace work?

A: Sometimes referred to as a controlled atmosphere furnace, a vacuum furnace is any furnace that removes air from the heating chamber during operation. A vacuum furnace system does this by utilizing an air purging pump and creating a seal that does not allow oxygen to enter the chamber while it is in use.

Q: 18. How thick of metal can you braze?

A: If both pieces of metal being joined are more than 0.5 in. thick, either method will work well. For thinner parts, however, brazing is go-to method. For example, creating a T-joint between 0.005-in.

Q: 19. What is the process of vacuum brazing furnace?

A: Basically, brazing is a process that combines elements with the use of a brazing material. Prepared elements with applied brazing material are placed in a vacuum furnace and heated up to brazing temperature (from 800 to 1150°C) which is higher than the liquidus temperature.

Q: 20. What is the difference between a vacuum furnace and an atmosphere furnace?

A: The difference between an atmosphere furnace and a vacuum furnace is that vacuum heat treatment technology is an integrated technology connected with heat treatment technology and vacuum heat treatment technology, which is a total and partial heat treatment performed under a vacuum.

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