Unlocking friction stir welding: 4 steps for high-quality welds
Unlocking friction stir welding: It may be interesting to know that there are 4 steps for successful or high-quality direct current welds with a consumable electrode.
One of the most significant advantages of FSW is that the process is very accurate to develop high quality and strong weld as compared with other traditional welding techniques. For better outcomes, it is advisable to be systematic in an approach that should be followed. From this article, the reader will learn about the four key procedures that help to achieve FSW’s potential and produce high-quality welds.
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Step 1: Clamping and positioning the workpieces
In FSW process, first step involves clamping and locating of the workpieces which needs to be joined. The orientation with regard to the material can substantially influence the result of the weld. There are two primary configurations: Butt welding and lap welding are most common, or rather widely used Welding processes.
Butt welding:
In this case one piece of material is laid alongside another and the edges of the two oriented in parallel to each other. It is especially suitable for making smooth connections which run in parallel to one another, with low distortion. Some of the general tips that can be observed when welding include; one should ensure that the edges are well clashed to prevent formation of gaps and over laps since they compromise the welds.
Lap welding:
Where joining materials, some of them might be of thin thickness or different types then lap welding is used. This configuration is where one piece of material overlays on another part’s of the material. Attention has to be paid to positioning and clamping for having a correct alignment of the overlapping sections that need to be joined by welding.
It is therefore important that the clamping system be rigid so as avoid shifting during the welding process since any shifting affects the quality of the weld produced.
Step 2: Select tool and tailor FSW tool
The FSW tool basically has a shoulder section and a pin section and also greatly contributes to the welding activities. There are certain requirements for the tool design which should depend on the type of materials used and the type of joints to be produced.
Tool geometry:
Location and size of the tool, the material from which it is manufactured influences the heat distribution process as well as mixture of the materials. Hence it is required to make appropriate changes in the tool geometry depending on the material and thickness while striving for better heat generation and stirring.
Tool preparation:
It is also important to make sure that the weld is in correct condition and properly positioned when beginning a weld. If for instance the tool is worn out, the heat produced on the weld area is also inconsistent and can affect the quality of weld made.
And here, when selecting the tool and preparing it for welding, one should follow the required criteria and standard, in order to produce the highest quality of weld.
Step 3: Exercise of control over parameters of work process
During FSW there are certain parameters that should be controlled in order to produce satisfactory welds. Key parameters include:
Rotation speed:
Several other factors influencing the entire process include the speed at which the tool rotates, the higher the speed the more heat that is produced. An effective stirring speed will enhance heating of the material while also enhancing its mixing up to serve the intended purpose.
Feed rate:
The speed at which the tool traverses the joint determines the time the workplace or the material is exposed to heat. Changing feed rate depends on type and thickness of the material enables one to have a steady weld.
Vertical force:
It means that the engagement between the tool and the material depends upon the force that is applied. Vertical force should be controlled effectively so that it does not lead to tool wear and workpieces deformation.
It is evident that monitoring and controlling of these parameters in real-time will enable one to obtain the desired welding condition and quality welds.
Step 4: Post-welding inspection and surface treatment
Normally, after welding has occurred, there are usually some checks that have to be made in addition to the finishing of the weld.
Inspection:
There must be voids, cracks or any other form of inconsistency in the weld. This may be done by simple visual examination of the weld or by using ultrasonic or radiography tests for instance.
Finishing:
In as much as this will be rare, there might be a need to do some treatments after welding so as to smoothen the surface and enhance the qualities of the weld. These can involve mechanical operations such as grinding and polished to give it a smooth finish or coatings to give it a resistance to corrosion.
The last is done in a right manner to achieve required quality of the weld and to ensure that the weld will be serviceable in its intended application.
