How to choose my FSW tool for my application?

Since the emergence of friction stir welding, many innovations have been made to improve the quality of FSW tools. These improvements result in better quality, more stable welds, and a certified lifetime. Today, many people are asking how to choose their FSW tool and how this choice will influence the quality of their weld. We propose to answer this legitimate question throughout this article. To start with, it is important to detail the composition of an FSW tool.

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The different components of a FSW tool: what is a shoulder and what is a pin?

A FSW tool consists of three parts: the body, the shoulder and the pin.

The shoulder is the part that heats the material by friction in order to soften the workpieces and thus enable the welding operation. This is its primary function. The larger the diameter of the shoulder, the larger the contact area, which increases the frictional capacity of the tool. However, too large a shoulder will cause the workpiece to heat up too much and reduce the strength of the weld. The size of the shoulder will therefore depend on the thickness to be welded.

In addition, the shoulder with its counter-cyclical spiral shape allows the material flow to be pushed back towards the centre to prevent it from leaving the welding area. This second feature will improve the surface finish of the weld and the quality of the weld. With this feature, there is no need to tilt the tool during the welding operation. This is because the spirals pull the material towards the axis, which prevents the material from slipping (see infographic below: “No more tilt angle required on the FSW tool”).

Tool attachment – Whistle notch systemShoulderPin

In addition, the spiral shape improves tolerance to weld seam offset, reduces burrs and makes variable thickness welds possible.

Second part: the pin – the extremity of the tool.

The pin is the part of the tool that will penetrate the material by mixing it through a shearing effect: this is the stirring. Indeed, due to its conical shape and its grooves, the pin heats the material and softens it in order to ensure the mixing of the materials and the quality of the weld. The flat tip of the pin allows better penetration of the tool and therefore reduces the risk of lack of penetration. The pin and its flutes allow stirring in the direction of tool rotation as well as vertical mixing of the material.

Heat is generated by the friction between the workpiece and the tool, which produces plastic deformation of the workpiece and welds the two parts together.

How does the quality of my FSW tool contribute to the quality of my weld?

The quality of the weld depends directly on the quality of the tool and the choice of the tool. We will see later how to choose the right tool for your specific application.
But first, let’s see how the quality of the tool affects the quality of your FSW weld. To understand this, it is important to keep in mind how a FSW welding operation works.

Friction Stir Welding in 4 steps

1

Clamping of the parts to be welded: side by side in a butt welding configuration, one on top of the other in a lap welding configuration. The tool does not depend on the welding configuration. The same tool is used for butt and lap welding.

2

The tool penetrates the material: the shoulder heats the material by friction and the pin seals the parts together.

3

Welding operation: the tool advances along the weld seam and mixes the parts together.

4

End of welding: the tool moves up vertically, leaving a hole.

As you can see, the tool geometry has an impact on the weld quality. The tool will directly contribute to the mechanical strength of the weld. How? By the strong mixing of the material by the pin and by the heat generated by the shoulder. These two phenomena will cause a recrystallisation of the aluminium which will result in the precipitation of fine grains and thus contribute to the very good mechanical strength of FSW welds.

However, at the end of the weld, the tool will leave an exit hole as you can see in step 4 of the infographic above. This is not a quality issue, but for some applications it is better to remove it. The solution: the retractable pin tool. Where a conventional FSW tool leaves an exit hole at the end of the weld, a retractable pin tool seals the hole directly at the end of the weld, without any further intervention.

With competitive price and timely delivery, World Wide Welding sincerely hope to be your supplier and partner.

Finally, a last improvement has been made to the FSW tools: temperature measurement of the weld in real time. The temperature measurement tool allows you to control your FSW weld in real time: it is a quality tool.

Smart tool holder – the temperature measuring tool: precision for successful welding

In addition to the functionality of a standard tool, the temperature measurement tool allows you to precisely measure the temperature of the weld in order to adjust your welding parameters finely and check 100% of the parts.

How does the temperature measurement tool work?

The FSW temperature measurement has two holders, one fixed and one rotating, each containing an electronic card. These electronic boards receive and send the signal from the probe in the tool to the software. Thanks to this system, it is possible to control the temperature of the weld in order to optimise all the welding parameters (rotation speed, feed speed, Z force).

The benefits of the Stirweld temperature measurement tool are:

• Real time temperature measurement for demanding FSW parts (space, aerospace and automotive applications),
• 100% quality control of FSW parts – compatible with EN ,
• Optimisation of welding parameters: increase of welding speed (from 20 to 100%).

As an example, the temperature measurement tool is very useful for the assembly of aerospace components according to EN .

How to choose my friction stir welding tool according to my application?

To choose your FSW tool, you need to take into account 4 parameters:

• The distance to be welded,
• The depth to be welded, which will determine the size of the pin and the shoulder,
• The tool geometry: for this point, Stirweld experts are present to help you define the tool geometry that will best suit your welding configuration – optimal heat and material stirring.
• The material of the parts to be welded: standard aluminium alloys, high strength aluminium alloys, aluminium casting, copper, aluminium-steel or aluminium-stainless steel dissimilar.

Stirweld has developed a range of standard tools for different markets and materials to be welded. To give you an idea of which FSW tool is best suited to your application, here are some examples of FSW tool choices depending on the application sector, the material used and the thickness to be welded.

FSW tool for your application

For example, for the aerospace sector, the FSW tool will be made of a high-strength alloy to suit the more demanding aluminium parts (2xxx and 7xxx series).

Another example is the automotive sector, where most parts are produced in aluminium casting. These alloys contain silicon, which is inherently abrasive. For this type of aluminium, we use tools made of ceramic, a material that is highly resistant to abrasion.

Stirweld supports you with a complete range of high quality FSW tools. One of our main references, the Ariane company, leader in the aerospace field.

What is the lifetime of an FSW tool?

There are two factors that influence the lifetime of an FSW tool:

• Cyclic fatigue: Fatigue exerted at the base of the pin causing the pin to pull out prematurely. It is due to the drag force, i.e. the force exerted as the tool moves through the workpiece.

• Abrasive wear: Fatigue exerted on the whole tool by friction in the welded material. This will cause wear on the shoulder spiral which affects the quality of the weld.

The life of the tool will also depend on the materials being welded: aluminium/aluminium, aluminium/copper, copper/copper, aluminium/steel.

FSW Stirweld tools have an average life of  metres of weld in a “classic” Al/Al welding configuration with a thickness of less than 8mm. In order to guarantee the quality of its tools, Stirweld uses a test bench.

We will assist you in the choice of your tool. Contact us without commitment.

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V-FSWC | VERTICAL FSW SERIES

With a commitment to precision and rigidness, Stirtec machines are designed to withstand all requirements within the serial production under the achievement of highest welding speeds. The FSW units within the V-series are conceived as 3-axis welding machines on a C-frame build design and are capable to be upgraded to additional 4th and 5th axis meeting the demands across several industries. The special developed FSW spindle system executed the welding process force controlled. Including the inline process monitoring STIRlytics®, process forces and real-life data collecting are combined into a quality report, which ensures full traceability throughout the FSW welding process. Due the installed machine control system of Siemens, the integration is handled easily for automation.FSW force control systemSTIRlyticsprocess monitoring software for data monitoringSmall machine footprintFull protection and CE-conformity

Overview of the vertical FSW series

V-FSWC550 COMPACT

• Application for welding: HV inverter, cooling units and heat exchanger​
• FSW machinery for high-volume production due to two separate operating machine tables

Download DatasheetV-FSWC550 COMPACTThe Stirtec V-FSWC550 Compact provides state-of-the-art Friction Stir Welding technology and is especially designed for industrial application with smaller dimensions on high-scale production volume. Due to its very small footprint and space requirements, the FSW unit can be easily installed in every new or existing production line to expand the customer’s portfolio with the technical Friction Stir Welding. Throughout the machine concept of the V-FSWC550 Compact, two separate machine tables are working individually and ensure simultaneous part handling while welding. The machine is predominately used for manual production in the ramp-up phase and can be easily upgraded with automation (loading/unloading via robotics).

Machine characteristics of Stirtec V-FSWC550 Compact

• application size up to L 400mm x W 400mm
• use of Sinumerik One machine control system
• STIRlytics process software for 100% traceability
• FSW force measuring system in X-, Y- and Z-direction
• highest repeatability and accuracy due to rigid machine frame
• suitable for all aluminum alloys and die casting components
• automatic/manual tool change system
• FSW spindle for welding forces up to 15kN, speed: 5.000rpm
• simultaneous handling of parts
• preparation for high TCS cleanliness requirements
• ultra small machine footprint for installation
• full protection and CE-conformity

For more information, please get in contact

V-FSWC

• Application for welding: Battery housings, cooling units and heat exchanger​
• FSW machinery for high-volume production with optional automatic pallet change system

Download DatasheetV-FSWCThe Stirtec V-FSWC is seen as a high-productive Friction Stir Welding center following the production of applications in the automotive industry for midsize battery systems for PHEV and cooling system e.g. heat sinks. The robust and stiff machine design allows the achievement of rapid welding speeds underfollowing the welding path with high accuracy. The machine type of V-FSWC is a proven solution that synthesizes latest FSW technology with upgradable milling functionality in a single production center (Stirtec 2-in-1 concept). Optional, the system can be upgraded with an automatic pallet change system for reducing the handling times for loading and unloading to a minimum–part handling manually or automatically according toour customer’s preferences.

Machine characteristics of Stirtec V-FSWC

• application size up to L 950mm x W 500mm
• use of Sinumerik 840D sl / One machine control system
• STIRlytics process software for 100% traceability
• FSW force measuring system in X-, Y- and Z-direction
• highest repeatability and accuracy due to rigid machine frame
• suitable for all aluminum alloys and die casting components
• automatic tool change system for 24 tool pockets
• FSW spindle for welding forces up to 15kN, speed: 5.000rpm
• Heidenhain absolute linear encoder leads to direct machine feedback
• outstanding technological and economic productivity
• upgradable milling functionality in a single machining center
• full protection and CE-conformity

For more information, please get in contact

V-FSWC

• Application for welding: electronic motor housings and PHEV battery trays
• FSW machinery with high-process reliability and possibility to weld in constrained areas (option for integrating additional axis)

Download DatasheetV-FSWCThe Stirtec V-FSWC is responsible for the production of a large variety of applications within the automotive industry for the FSW welding process on EV battery trays and electric motor housings. The robust and stiff machine design allows the achievement of rapid welding speeds under following the welding path with high accuracy. The V-FSWC machine type stands out as a global solution, seamlessly integrating cutting-edge FSW technology with upgradeable milling functionality within a singular production center (Stirtec 2-in-1 concept). With the capability on integrating additional axis (4th and 5th axis), limited accessibilities for welding can be achieved.

Machine characteristics of Stirtec V-FSWC

• application size up to L mm x W 600mm
• use of Sinumerik 840D sl / One machine control system
• STIRlytics process software for 100% traceability
• FSW force measuring system in X-, Y- and Z-direction
• highest repeatability and accuracy due to rigid machine frame
• suitable for all aluminum alloys and die casting components
• automatic tool change system for 24 tool pockets
• FSW spindle for welding forces up to 40kN, speed: 5.000rpm
• Heidenhain absolute linear encoder leads to direct machine feedback
• spindle headstock with thermal stabilization
• upgradable milling functionality in a single machining center
• full protection and CE-conformity

For more information, please get in contact

Applications for the Vertical FSW Series

E-Mobility

The cooling circuits of battery trays, stator housings, and inverter housings in electric vehicles are sealed watertight using Stirtec's FSW machines. Stirtec's FSW machines are excellently suited for manufacturing battery trays due to their high welding quality.HV Inverter HousingsElectronic Motor HousingsEV / PHEV Battery TraysFind out more about E-Mobility