VPE Precision Brazing Capabilities
Our strong engineering solutions and project management skills allow us to complete many challenging research and design projects and provide contract manufacturing services for critical applications.
Precision Brazing
- Vacuum brazing
- Hydrogen furnace brazing
- Induction brazing
- Infrared (quartz lamp) brazing
- Aluminum vacuum brazing
- Controlled atmosphere
- Controlled dew point
- Diffusion
- Inert gas
- Laser and torch
- Pressure-assisted (applied force)
- Retort
- Ultra-fast
- Joint design to meet service requirements
Parent Materials Brazed by VPE
- Aluminum
- Aluminum nitride
- Aluminum oxide
- Brass
- Ceramics
- Composites
- Copper
- Glidcop™
- Havar™
- Haynes
- Inconel™
- Invar™
- Kovar™
- Molybdenum
- Nickel
- Platinum
- Reactive materials
- Rhenium
- Silver
- Stainless steel
- Tantalum
- Titanium
- Tungsten
- Tungsten carbide
- Vanadium
Considerations & Critical Process Parameters
Applied Force
By applying a force during precision brazing, we can reduce the uncertainty of whether or not the mating surfaces are predictably seated against one another. The force can be applied through the use of a deadweight, hydrostatic pressure, differential thermal expansion effects, or an active force from a hydraulic ram.
Assembly Features
With increasing frequency, there are instances where the design of a brazed joint is constrained by assembly features that would render the assembly “not brazeable” if conventional design criteria were applied. We have found that these assembly features are driven by factors that include:
- Component geometries that are becoming much smaller
- Materials innovations
- Market competitiveness
- New machining innovations
Biocompatible Materials for Medical Applications
Thin film metalized ceramics for miniature feed-throughs used in medical devices require the use of specific biocompatible materials. Yesterday’s materials choices are not acceptable in these applications. Biomaterials are often reactive and limiting; accurately controlling the time-at-temperature makes some designs suitable that would otherwise not work.
Capillary Action
A key factor in precision brazing is capillary action, which ensures proper filler metal distribution. It is of particular importance when brazing assemblies that incorporate microchannels and other small features.
Diffusion Brazing and Transient Liquid Phase Diffusion Bonding
These processes can provide a brief period of liquid at the joint interface, helping to achieve intimate contact. The liquid will solidify isothermally under correct processing to achieve high-strength bonds.
Filler Alloy Type
In conventional brazing, “in-stock” or “inventoried off-the-shelf” forms of filler alloy are used for the sake of convenience. In precision brazing, the alloy chemistry appropriate for the application is selected or developed to meet strength and environmental/service requirements.
Filler Alloy Quantity
In precision brazing, serious consideration is given to determining how much filler alloy should be used for a given assembly. The rule of thumb of using 125% to 150% of joint volume as the amount of filler alloy to employ is challenged.
Filler Alloy Application Technique
Precise placement of the filler alloy is achieved using precision-fabricated pre-forms produced by EDM methods. They are used to help keep the filler alloy away from capillaries. These may be applied by:
- Foil, wire, and powder—by hand, pneumatic, or robotic techniques
- Wet plating
- PVD coatings
Filler Alloy Flow-Arresting Features
To impede the flow of filler alloy, channels (or even sharp corners) may be used.
Filler Alloy Metallurgy and Metallurgical Reactions
Filler alloys may react to form lower-melting eutectics with consequences that are often difficult to predict. When performing precision brazing services, we frequently make use of metallurgical reactions to obtain optimal brazing results.
Joint Design—Volume, Volume Control, and Assembly Fit-Up
Knowing the joint volume is important in determining the amount of filler alloy to use. Our design engineers review assembly tolerances to assure that the assembly performs as intended in service and that an optimal amount of brazing filler metal is utilized.
Rapid Brazing
Undesirable brittle inter-metallic reactions can be avoided by using rapid brazing processes.
Time-Temperature-Applied Force Profile
With a time-temperature-applied force profile, fundamental parameters have the capacity to alter metallurgical reactions. VPE considers the role of each parameter carefully when designing critical assemblies.
Other Important Process Parameters
- Interface chemistry
- Production tooling design
- Selective enabling or limiting capillary action
- Service environment—hermeticity, corrosive, temperature, stress, life, creep, and fatigue
- Temperature profile design
Examples of Precision Brazing Applications
- Aerojet Rocketdyne: satellite thruster nozzles
- Fortune 10 corporation: reactor and gas turbine components
- Major aerospace contractor: engine fire sensors
- Major medical device corporation: ceramic-to-metal heater assemblies
- Major medical and industrial corporation: ceramic to metal electrical seals
- NASA: Space Exploration and Lander Programs
- Microchannel devices, such as microchannel heat exchangers
- Detectors
- Cathodes
- Cold Plates
- Biomedical Assemblies
- Microwave Devices
- Electron Accelerators
- Cyclotrons
The World’s Largest Vacuum Hot Press Furnace
VPE currently owns the world’s largest vacuum hot press furnace, which is perfectly suited for brazing, bonding, and hot pressing. The usable chamber area is 60 inches wide, 120 inches long, and 120 inches tall. This immense furnace is rates for temperatures in excess of 1900° Celsius in vacuum and partial pressure atmospheres. Two independent 1200 ton rams allow for loads to 4.8 million pounds, while ten high accuracy load cells allow precision force and precision control on the production elements.