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Laser welding of sheet metal assemblies

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Carl Benz developed his first motorized three-wheeled vehicle in Mannheim in 1885 and registered it for a patent on January 29th, 1886, marking the birth of the car. The simple three-wheeled vehicle he created had little in common with what we understand as a car today.

An average car produced today consists of up to 10,000 individual parts. Most components in today's cars are made of metal or plastic, and almost all of them have one goal in common: optimization for maximum safety and minimum weight. Automotive companies purchase almost all of the parts they need from specialised suppliers. These suppliers, in turn, must share this goal if they want to be interesting potential partners. 

Just in time

The principle of “just in time” manufacturing applies not only in the automotive industry, but in almost all supplier industries today. Because logistics chains are so tightly linked, their various dependent processes are also highly susceptible to disruption. Just in time manufacturing helps reduce warehousing costs and the associated complexity of the connections and contexts. This means that the processes within these logistics chains themselves must be highly secure and stable. Of course, the products within these logistics chains also need to have low scrap rates, since incoming goods inspections may not be possible with such fast product cycles. Processes that stall out or stop generate high costs and make suppliers unreliable in any production area. The expectation is that products in this production process will offer outstanding quality, all but eliminating the need for reworking. Since all producers are also subject to global competition and pressure, this high quality must also be produced at the least expensive, most competitive price. 

Growth in expertise and know-how

Producers are looking for an “all-inclusive-solution” that can fulfil these demands – maximum safety and minimum part weight, low rate of disruptions in the manufacturing process and reduced costs – while still reducing costs.

Especially in the area of forming technology, there are many suppliers who are most interesting to manufacturers, and most likely to survive, if they make it possible to deliver this “all-inclusive-solution”. Suppliers who want to focus on this goal need to take a close look at each of their process steps to identify potential areas of improvement. At the same time, every producer’s economic goal should be to generate value in-house, not giving away a large percentage of its yields by purchasing parts. And when this goal is linked to a growth in expertise and know how – all the better! This helps companies become economically stable and secure for the future; development continues every day, and it is important not to fall behind, but instead to be a part of this development.

Example: Steering column optimization

Let's take a car's steering column, for instance: while Carl Benz's first car used a crank-operated vertical steering rack to steer, today this element – along with the airbag and safety belt – is just one part of the vehicle's safety system.

All of the parts installed in collapsible steering columns are important as well.

Originally, many of these elements installed in the steering column were made of cast iron. Since cast iron is a brittle material, it offers excellent inherent stability. In steering column applications, however, this characteristic is not beneficial. It is important from a safety standpoint that the steering column components can deform, for instance to absorb some of the energy during an accident. Cast parts typically cannot do so.

From cast part to sheet metal assembly

Today, the elements in the steering column are manufactured by forming and welding. Sheet metal assemblies produced by forming stand out for their dynamic rigidity, a key property in the collapsible steering column concept. In addition, sheet metal assemblies fulfil the automotive industry's demand that the installed parts be as lightweight as possible, contributing to overall weight reduction in the car. Cast parts are typically solid, giving them a high weight and contradicting the goal of using the lightest parts possible. Cast parts also typically need to go through mechanical reworking, for instance by milling them to fit and removing burrs. This increases production costs. In addition, today the main suppliers of cast iron are in China, and the material has to travel a very long distance for processing. Long transports are always associated with a risk of loss, and can quickly interrupt the sensitive balance of the logistics chain as described above.

Produced cast parts are not flexible, and are an example of old fashioned monoblock technology.

Cast iron is also a material that is difficult for employees to work with.

Joining processes like bonding and soldering also are not good alternatives in many areas, since they cannot be used in high temperature applications. Such connections fail at high temperatures, such as those produced in the exhaust system, and the component malfunctions.

Welding is the alternative to many joining processes. Shapes are punched from steel or stainless steel panels and combined to create new sheet metal assemblies using a modular, flexible work process. Forming can also be used to produce a wide variety of components.

Another advantage of forming processes is that they can be combined in sequence for the most efficient  low-cost use of resources 

The entire supply chain, from sheet metal to finished product, remains within the company. Overall, welding is a much cleaner manufacturing process than casting parts, for instance. In addition, it delivers a reliable final product with high precision that can also be produced cheaply.

MIG, MAG or LASER

There are also different types of welding, however: In MIG and MAG welding processes, the welder works with melting wire electrode, a solid or flux cored wire and an inert gas, which can result in weld spatter and manual reworking. This, in turn, makes the entire process more expensive. Looking at a MIG/MAG welded seam from the outside, you will see a fat and unattractive weld bead. 

In laser welding (LASER = Light Amplification by Stimulated Emission of Radiation), energy in the form of light is highly concentrated and focused on a small point. Bundling the energy onto a very small surface creates a “keyhole” in the direction of the beam, a cavity filled with metal vapour extending to the depth of the workpiece. The liquid material created collects behind the keyhole, comes together, and forms the welded seam. This creates deep and elegant, lean welded seams with a very narrow heat-affected area. In comparison to the overall sheet, the heat impact is so low that there is almost no thermal distortion. The consequence is that parts can comply with much stricter production tolerances.

Sheet metal assemblies produced using this process often need no mechanical reworking, and offer sufficient precision to be integrated directly into the logistics chain. Therefore, LASER welding is a very inexpensive option for mass production. In addition, this technology is clean and innovative, making it attractive for any manufacturer looking to optimise their production processes.

Small heat impact zone - low component distortion

Since the development of LASER welding technology for welding sheet metal assemblies, the technology has developed rapidly. Today, steel quality has improved such that the usable focus diameter can be much smaller, even on large pieces. While past laser welding was more like working with an axe, today's laser welding is more like a surgical scalpel. Thanks to the lower heat impact zone with reduced point diameters, welders can now weld materials considered very difficult just a few years ago: Aluminium and copper materials, for instance, that are becoming more important in electro-mobility:

When manufacturing batteries and battery packs, it is important to securely connect different materials, such as aluminium and copper, using a secure contact and with short process times.

Battery covers, typically made of aluminium materials, must also be connected safely and tightly to ensure battery function and service life.

Since a majority of the population is interested in growing electro-mobility, this is considered another promising field for LASER technology.

We should also mention that many high-strength steels are predestined for LASER welding due to their metallurgy. These materials can be formed and laser welded into elegant, lightweight and highly rigid designs.

All of these examples show that LASER welding is a forward-thinking technology that helps suppliers get ready for the future by focusing on new applications. LASER welding creates opportunities for new products that help companies keep ahead of the game.

Automated clamping devices are the key to success

As exciting as welding sounds and, from an objective standpoint, as exciting as it is, the parts to be welded must be prepared and clamped correctly to obtain optimal welding results.

Since laser seams are very narrow, the right component alignment under the laser beam is the key to success.

This starts with designing the assembly for laser welding, includes the design of the clamping materials, and ends with an optimised welding strategy.

To achieve short cycle times and eliminate the need for workers to insert materials, most of these clamping processes are automated.

A well designed clamping device and process management is a key advantage in producing products that fulfil the highest quality requirements while generating minimal scrap rates.

As is so often the case, finding the right combination of multiple components and ensuring they work together perfectly is the key criterion that ultimately decides whether you receive outstanding results. It is important that machinery optimally joins and fixes the materials using a well designed  clamping device, in order to use inexpensive, reliable LASER welding technology to create a high-quality, low-cost product.

It is important to review this new technology alongside a partner whose core areas of expertise are automated clamping and automated LASER welding. Your partner’s goal should be to support manufacturers deciding to try laser welding, developing creative solutions alongside you to develop an “all-in-one solution”.

The welding system's processes and planning should help produce a result optimally tailored to your needs, while using resources efficiently. Manufacturers of sheet metal assemblies, or manufacturers who want to produce sheet metal assemblies, can create products that fulfil the demands for an “all-in-one solution”:  Stable processes that produce high-quality sheet metal assemblies at low unit costs. weil technology offers a wide range of system concepts that help us focus on the assembly and welding tasks our customers need to develop the best option. Different material feeding and removal concepts, a variety of testing and control stations, robotic handling or conveyor delivery and removal are all individually adapted to the customer’s requirements. The systems we design often offer the pleasant side effect of taking up much less space, reducing required manufacturing space by up to 25%.

With a system builder like weil technology as your technological partner, helping suppliers to reach a higher level of technology in-house through individual machine solutions and training, you can become a reliable partner to any manufacturer and focus on the future. Generating value in house also lets you secure the future of your company and gain independence from global material flows. You can use your newly gained skills in manufacturing sheet metal assemblies, clamping, and LASER welding to launch additional products, expanding your supplier product range and getting you ready for the future.

With weil technology at your side, we can develop you into a reliable and attractive partner for many different manufacturers.

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