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Path to productivity

Process knowledge is key to achieving desired production rates and yields for laser welding, cutting and marking

Industrial process success is most commonly defined by two parameters – production rate and yield. In the simplest terms: Make as much as possible in the shortest amount of time. Understanding the process requirements and production environment allows companies to optimize their production rates, resulting in lower cost per part and higher profit.

A number of factors influence process success, including material selection, equipment capability and process requirements. Optimization often takes several rounds of testing and improvement. However, the production environment, including personnel, budget, climate and other factors, might limit the options for equipment selection.

Spatter can be seen in the fiber laser seam weld. Generally, it’s best to avoid, but for some materials and weld requirements, there is always some present. Excessive spatter, however, can result in poor weld quality.

Understanding process requirements – and the production facility – aids in the design of robust systems for production that will increase the production rate and yield. While there are several process requirements that a fabricator must understand, this article focuses specifically on laser welding, cutting and marking processes and discusses equipment selection for them.

Systematically defining each process is critical. There is a difference between conducting a first-level study that achieves success in an application laboratory and running a fully developed process that is repeatable and can deliver high yield with consistency. If not defined methodically, the process may fail.

At Amada Miyachi America, a “Define – Design – Deliver” methodology is used in its technical center application laboratories that seeks to define not only the equipment but also the best process through clear system design. This methodology recognizes that laser process knowledge is as important to success as the laser source itself, and it applies the same level of engineering rigor to the design of the process as the equipment.

In-depth discussion

A key component to Amada Miyachi’s methodology is conducting in-depth conversations with customers about their overall goals. Initial discussions may last an hour or two, followed by one or more visits where the application development team and customer discuss how to best achieve the desired goals. These initial meetings center on a few core questions.

The key questions in determining the correct process and equipment for an application focus on customer parameters, including the material and plating to be used, weld geometry, part shape and size, desired penetration depth and weld target time. Information on the desired characteristics of the weld, such as pull, torque, peel and whether hermeticity is required, also informs this step.

Customers should consider:

  • What are the production goals or target success rates?
  • What is the current welding process?
  • What is the cycle time?
  • Is the process going to be performed now or is it planned for the future?
  • If now, why are they looking to change? Is the current system too slow, for example? Not enough penetration?
  • Is tooling needed?
  • What is the timeline of the project?
  • What is the budget for the project?

Of course, there are a host of questions to consider beyond the basics. For instance, the climate of a factory could impact the range of potential optimal solutions. Some lasers may not perform as expected in a facility that lacks air conditioning that is, for example, located near the equator.

A plume from laser spot welder on stainless steel using a pulsed Nd:YAG laser. Experienced laser welders look for the tallest, brightest and loudest plume to determine focus and first indications of process success.

As the systematic consideration of the job continues, the question of priorities often emerges. Sometimes, this conversation reveals that a laser welding solution is not ideal for an application. Experts could determine that a customer’s interest in a faster cycle time requires a transition to laser welding, but perhaps they lack the budget for new equipment. In this case, application experts could develop a robust resistance welding process but also help them position for a future transition to laser welding. By thoroughly addressing a battery of questions, application engineers can effectively triangulate the best solution for each customer.

Efficiency factors

After discussing goals and parameters, Amada Miyachi can begin formulating an ideal solution for the application. The basic factors that impact productivity include materials, equipment and process. Often, reworking even just one of these elements enables a customer to reach production goals.

While materials are often predefined by customer needs, they may not always be optimal for welding. Experienced application engineers, however, can help ensure success. As an example, a customer’s production line employed a mechanical crimping and welding technology to join brass wires. They wanted to move from resistance welding to laser welding, but brass contains too much zinc to be effectively laser welded. The solution, therefore, was to replace the brass with bronze or pure copper followed by Amada Miyachi assisting with the development of a new production line that could embrace the speed and precision of laser welding.

Equipment selection is another area in which application knowledge is vital. Unlike resistance welding, laser welding is a non-contact process that doesn’t utilize electrodes to hold parts in place, so customers must develop part fixturing. Fortunately, application experts can help with this as well by suggesting a range of standard tooling or helping to design custom tooling.

The process, too, can be revised to unlock production potential. In some factories, customers seek to perform a butt weld to join two pieces with beveled or round edges so the parts will not be sharp. However, this process can diminish the likelihood of a successful laser weld.

Two pieces with rounded corners pushed flush to each other meet below the surface, with no metal in the area between parts. This lack of material can make it impossible for a laser to effectively melt enough metal to create a weld of decent strength. In this case, application experts might suggest a process in which operators can round off corners after the weld has been completed.

Defining the solution

After discussing the customer’s goals and parameters, conversations often lead to sampling. Here, application engineers process customer samples using similar equipment and settings to demonstrate possible outcomes and then send them to the customer for review. Customers may find the first pass to be just what they are looking for, or not. Whether the sample reveals a need for faster cycle times or more depth penetration, sample processing is an essential step in determining the best process.

Upon determining that samples meet desired parameters, engineers design a preferred solution or a short list of potential fits. For laser welding, available options include pulsed Nd:YAG and fiber lasers. These technologies are largely capable of the same performance but differ with regard to serviceability. A pulsed Nd:YAG laser is field serviceable whereas a fiber laser must be sent back to the factory for repair and servicing.

In the marking area, several units can do the same job, but there are fine distinctions among them; selection is based on process-specific requirements. For example, the new WL-300A laser processing workstation, configured for nanosecond pulsed fiber laser applications, can handle a variety of mark types. Though primarily designed for laser marking and engraving applications, the laser source can also be used to weld and cut thin metals up to 0.010 in.

This laser welding workstation shows a floor-standing unit equipped with an ergo-arm and computer.

Integrated with Amada Miyachi’s LMF fiber lasers, the WL-300A unit features a precise motorized Z-axis for easy focus adjustment, easy access to parts and tooling, and an optional XY table for step and repeat motion. An optional compact motorized rotary axis makes marking and welding cylindrical parts easy and fast. The workstation also provides for easy part fixturing.

The design of the laser equipment itself centers on three elements: the laser, beam delivery and motion. Once an Nd:YAG or fiber laser is selected, the delivery mechanism is developed. Fiber delivery often calls for a focus head, which can be set up in a variety of configurations.

Once the laser beam has been delivered to the part, motion is required to enable the beam to contact the part at multiple spot weld sites or along seams. Lighting or vision capabilities to identify laser location on a part provide critical functionality. Experts may add cover gas, as well. The specifics of these mechanisms are closely linked to the intended use of the laser. For example, marking applications may include barcode scanners.

Experience understanding the complexities of certain industries allows application engineers to quickly factor in industry-specific requirements and testing requirements. At Amada Miyachi’s application laboratories, 80 to 90 percent of sample processing projects involve work that bears a high degree of similarity to other projects that application experts have worked on previously.

One example is the welding of battery packs, specifically cylindrical lithium-ion rechargeable or AA batteries. The tab material has not changed, but many manufacturers are now building battery packs into hand-held power tools, electrical vehicles and lawn mowers. These applications are similar enough to other successful existing solutions that the company can frequently speed up process development.

With a deep understanding of laser welding, cutting and marking processes, Amada Miyachi application engineers can help customers develop a solution, but it’s important that customers understand the elements of an effective process, as well. Whether transferring an existing production line to a new technology or building a new line, look for a partner that can provide part design, application knowledge, a machine tailored to the process, a breadth of light source selection, as well as pre- and post-sale equipment and application support.

In collaboration with laser experts, engineers can optimize production rates and yields by considering the multiple facts of the application, comparing their application to other proven process designs and taking advantage of opportunities to hone production by changing equipment, process or materials.

Amada Miyachi America

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