In this MTI Whiteboard Wednesdays: Friction Welding Flash video, we explain what flash is, why it forms during the friction welding process, and how to manage it as part of a comprehensive weld development and production strategy. Flash is a natural result of solid-state joining, created as heat and force plasticize the material and forge the two parts together.
You’ll also learn why flash control matters for part design, weld quality, post-weld machining, and production efficiency. From weld development through contract friction welding services, MTI helps customers understand every step of the process so their parts are built for strength, consistency, and repeatability.
Learn more about MTI’s Low Force Friction technology and how it prevents flash.
Thanks for joining me for MTI’s Whiteboard Wednesdays. I’m Dan Adams. Today, we’re talking about friction welding flash.
One of the frequently asked questions about friction welding is about flash formation. As we heat the two parts up and the material at the weld interface softens, it starts to extrude away from the weld interface. That extruded material is called flash.
Here’s a linear friction weld between copper and aluminum. The thermal conductivity properties of copper don’t allow any displacement from the copper, but you do see material displacement from the aluminum. Here’s the flash formation.
Here’s another linear friction welding example where we have an odd-shaped weld geometry, and as a result, you get an odd-shaped flash.
In the case of rotary friction welding, we can calculate what the flash is going to look like prior to welding so that we can help you accommodate that flash in the design of your part.
Here’s a section view out of a thick wall, large-diameter tube. This might be 15 inches in diameter. Now, the flash formation on the OD and the ID is volumetrically equal.
The other important part about flash formation is any material that’s on the weld interface—any contaminants, for example, coolant or grease—will get expelled as part of the welding process out into the flash, and the weld is essentially self-cleaning.
Here’s an example of an automobile airbag inflator where we leave the flash on after welding. Now this flash is integral to the assembly. It’s not going to flake off, it’s not going to come apart in operation, but in some cases, it can be left on. If the flash is going to be a stress riser for your part, or your application dictates that the flash needs to be removed, then we can do that in the machine. It can be done by turning, shearing, or milling.
Now, friction welding flash formation is an integral part of the process. It can be an advantage because it does allow the process to be self-cleaning at the weld interface. It can be left on if your application dictates, or it may need to be removed. If it needs to be removed, it can be done in the machine, or it can be done as a post-welding operation.
Thanks for joining us for this episode of MTI’s Whiteboard Wednesdays. For more information on this topic or other friction welding solutions, please visit our website at mtiwelding.com.