Friction stir welding manufacture liquid cold plates?

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Friction stir welding manufacture liquid cold plates?Introduction

Friction stir welding (FSW) is an innovative joining process that has revolutionized the manufacturing industry. It offers numerous advantages over traditional welding methods, such as improved mechanical properties, enhanced productivity, and reduced defects. In recent years, FSW has found its application in the manufacturing of liquid cold plates, which are crucial components in the cooling systems of various electronic devices. This blog post aims to understand friction stir welding comprehensively and how it is utilized to manufacture liquid cold plates.

What is Friction Stir Welding?

Invented and developed by The Welding Institute (TWI) in the 1990s, Friction Stir Welding (FSW) is a solid state welding process. Unlike conventional welding techniques that involve melting the workpieces, FSW achieves a solid-state bond using a specially designed tool to generate frictional heat and mechanically stir the materials together.

The FSW process involves several key components and steps:

Components of Friction Stir Welding

1. Tool: The FSW tool is a specially designed rotating cylindrical probe made from a rigid material, typically tungsten carbide or polycrystalline cubic boron nitride (PCBN). It consists of a shoulder and a search, with the latter having a unique geometry that facilitates material movement.

2. Workpieces: The joined materials, such as metals or thermoplastics, are called workpieces. These can be in the form of sheets, plates, or even pipes.

3. Fixture: A fixture is used to securely hold the workpieces in place during welding, ensuring proper alignment and minimizing distortion.

4. Clamping System: A clamping system applies the necessary force to hold the workpieces against the fixture and prevent movement during welding.

Steps of Friction Stir Welding

1. Setup: The workpieces are prepared by cleaning debris and applying clamping fixtures to hold them in place.

2. Tool Insertion: The FSW tool is inserted into a pre-drilled hole or placed on the joint's surface.

3. Rotation and Traverse: The tool is rotated and traversed along the joint line at a controlled speed and pressure. As the tool moves, it generates frictional heat, softens the material, and creates a plasticized region.

4. Material Stirring: The rotating probe of the tool mechanically stirs and mixes the softened material from both workpieces, forming a solid-state bond.

5. Cooling: After the tool passes, the joint cools and solidifies, resulting in a solid and defect-free weld.

The Advantages of Friction Stir Welding

Friction stir welding offers several advantages over traditional welding methods, making it a preferred choice for many applications. Let's explore some of the key benefits:

1. Improved Mechanical

FSW produces joints with excellent mechanicPropertiesal properties due to the unique solid-state nature of the process. The absence of melting and rapid cooling associated with conventional welding methods minimizes the formation of defects, such as porosity, cracks, and solidification microstructures. As a result, FSW joints exhibit enhanced strength, fatigue resistance, and elongation properties.

2. Reduced Distortion

Conventional welding often causes significant distortion due to the high heat applied and cooling required. In FSW, the heat generation is localized, and the relatively low temperature of the process minimizes distortion. This characteristic is particularly advantageous for thin-walled structures, such as liquid cold plates, where dimensional stability is crucial.

3. Increased Productivity

FSW is a highly efficient process that offers increased productivity compared to traditional welding methods. Since the materials are not melted, there is no need for consumables like filler materials or shielding gases. Additionally, FSW can be conducted at high speeds, enabling rapid production rates and reducing manufacturing lead times.

4. Versatility

One of FSW's outstanding features is that it can join many different materials, including aluminium, copper, stainless steel and even dissimilar metals. This versatility makes it ideal for various industries, from automotive and aerospace to electronics and renewable energy. The ability to weld different materials is particularly relevant in manufacturing liquid cold plates, where the cooling channels are typically made of copper, and the baseplate is often aluminum.

5. Environmental Benefits

The solid-state nature of FSW eliminates the need for potentially harmful shielding gases, fluxes, or filler materials. This aspect makes FSW an environmentally friendly welding process, reducing the generation of hazardous fumes and decreasing the overall carbon footprint.

Friction Stir Welding in Liquid Cold Plate Manufacturing

Liquid cold plates are essential components in the cooling systems of electronic devices, where they efficiently transfer heat generated by high-power members to a cooling liquid, such as water or coolant. Friction stir welding has emerged as a preferred method for manufacturing liquid cold plates due to its unique advantages and suitability for joining dissimilar materials. Let's dive deeper into the FSW process as applied to liquid cold plate manufacturing:

Design and Material Selection

The first step in manufacturing a liquid cold plate using FSW is determining the design and selecting suitable materials. The design should consider factors such as thermal performance requirements, pressure drop limitations, and compatibility with the cooling liquid. Aluminum is commonly used for the baseplate due to its excellent thermal conductivity and lightweight properties. Copper is often selected for the cooling channels due to its superior heat transfer capabilities.

Preparing the Workpieces

Once the design and material selection are finalized, the baseplate and cooling channels are prepared for the FSW process. The joint surfaces must be cleaned and free from contaminants to ensure a high-quality weld. Pre-drilled holes may be necessary to facilitate the FSW tool insertion, depending on the material thickness and design.

Fixturing and Clamping

Fixturing and clamping systems are employed to ensure proper alignment and minimize distortion during the welding process. These fixtures securely hold the workpieces and apply the necessary force to maintain appropriate contact between the FSW tool and the joint line.

Friction Stir Welding Process

With the workpieces properly prepared and fixtured, the FSW process can begin. IF REQUIRED, the FSW tool is positioned on the joint line and inserted into any pre-drilled holes. The tool is then rotated, and the traverse speed is controlled to achieve the desired dwell time in each standard section.

As the FSW tool moves along the joint line, it generates frictional heat through the rotation and applies downward pressure to soften the material. The tool also mechanically stirs the cushioned material from both workpieces, creating a defect-free weld.

Post-Welding Inspection and Finishing

Reprinted from - Custom Radiator, Custom Liquid Cold Plate Manufacturer