Copper Brazing is HI TecMetal Group, Inc. competency, however, HTG provides both welding and brazing services. This is an advantage for you when working with a metal joiner. Our goal is to utilize the best fit, form and functionality design and manufacturing processes in order to produce the best product for the application.
When considering copper brazing which is a metal joining process, we do choose for a particular assembly, several factors should be considered: strength and permanence, the physical characteristics of the parts, the shape of the joint, and the production level desired.
Copper brazing is a preferred method of joining components when strength and quality are primary considerations. HTG performs copper brazing is continuous exothermic furnaces using a pure copper filler metal. Brazing is viewed as a more robust process than welding.
Advantages and Limitations Of Copper Brazing
Brazing and Metal Treating is a specialist in the field of production copper brazing in an exothermic atmosphere. Our brazing services are most frequently used to produce brazed joints simple to complex metal parts. The basic advantages of our copper brazing process are:
Some disadvantages of Copper Brazing:
- Rapid Cycle Time
- Precise Control of Time, Temperature and Atmosphere
- State-of-the-art Equipment
- High Quality and Repeatability
- Less Expensive than Welding
- Full Penetration of the Braze Ally throughout the Braze Joints
- Differing Joint Designs Require an Engineered Approach
- Experimentation Prior to Actual Production is Desired to Develop the Best Braze Results
- Filler Metal Selection is Limited
Copper Brazing Procedures
When copper brazing, the standard steps that are followed in any other brazing process apply, such as joint design, alloy selection, and surface preparation. However, additional parameters must be considered such as: pre-cleaning the components to be brazed, method of assembly, part size and configuration, joint design, control of tolerances, quality and cost considerations.
The filler metal is drawn into the joint by a pulling force known as capillary action during the heat cycle. It is particularly important to maintain right amount of gap [space] between the mating parts to allow the dynamics to occur. The strongest copper braze joints are made by maintaining a press fit with a tolerance of +/- .002". This will create the proper gap [space] for the filler metal to flow into the joint area and prevent braze voids or porosity to occur. Wider spacing will result in a weaker braze joint. Little clearances are preferred capillarity action to draw the braze filler metal throughout the joint area.
Braze joint voids or shrinkage cavities may form as the pure copper filler metal solidifies. The optimum joints are those in which the entire joint area is wetted and filled by the filler metal. Again, it is best to avoid clearances that range from 0.001 to 0.003 in. Parts that maintain a line-to-line press fit with a tolerance of =/- .002" should be designed and controlled for the best capillary action and greatest joint strength.
It is also important to keep in mind that metals expand and contract at different rates when heated and cooled. Particularly when joining dissimilar metals, expansion/contraction rates must be allowed for when designing the part. Positioning the parts is best accomplished through self alignment or press fit operations and by utilizing the best type of braze joint configurations in the part design. [See American Welding Society Braze Manual for more detailed information.]
Selection of joint type is influenced by the configuration of the parts, as well as by joint strength and other service requirements, such as electrical conductivity, pressure tightness, and appearance. Also influential in the selection of joint type are fabrication techniques, production quantities, and methods of placing the filler metal at or near the joint to be brazed. Lap joints are generally preferred for furnace brazing processes. Lap joints should be at least as strong as the weaker material being brazed. For maximum strength, lap-joint length should equal three to four times the thickness of the thinner member.
Copper Brazing Engineering
Copper Brazing and Soldering Expertise
The use of brazing and soldering is becoming more widespread due to their practicality has a choice for manufacturers looking for creative ways to reduce manufacturing costs and/or join complex geometries that may have components made of different base metals.
Quality control and application engineering are very important factors to consider at the beginning of a design stage in order to ensure a competitive advantage and successful braze results. Contact HTG Engineering Group at the early stage of your product development in order to achieve the greatest impact from your brazing program and to ensure consistent quality results.
The benefits of Hi TecMetal Group experience
HTG metal joining engineers, technical staff and quality personnel will provide support to help your business produce high quality products:
HTG experts have hands-on experience with AWS, AMS, Nadcap and ASME Boiler and Pressure Vessel Codes, including the use of aluminum, copper, silver, gold, and nickel filler metals to braze both metallic and non-metallic materials using common heating methods such as furnace, torch, induction and resistance brazing.
- Evaluation of braze joint design, tolerances and manufacturing
- Possible part redesign for cost reduction or quality improvement
- Review of fit, form or functional characteristics to meet braze process requirements or reduce production costs
- Provide input on non conventional and conventional methods to produce a brazed part
- Critique the product in order to eliminate the possibility of rejects due to leak issues
- Evaluate braze joint strength properties and requirements
- Provide suggestions in order to obtain optimal part preparation methodology
- Assist with the selection of filler metal
- Develop procedures and qualification in accordance with Nadcap, AWS and ASME Codes
- Conduct in-house audits of brazing process