Non-stop production possible

ASM Assembly Systems, Munich (Germany)

Considering the entire value chain from PCB to placement to final assembly to packaging and product descriptions for exporting all over the world, Danfoss Power Electronics A/S in the Danish town of Graasten handles around 50.000 active product versions, and the numbers keep rising. The company produces exclusively based on made-to-order and one-piece flow principles. There is virtually no on-spec production and no finished-products inventory. The customer contracts state that the production must not exceed 24 hours.

The plant operates in three shifts on weekdays and in two shifts on weekends, 355 days a year. In the past it was possible to handle the product diversity and the required quantities with more or less permanent family setups on the SMT lines. But based on sales and portfolio forecasts, management decided in late 2010 to consider alternative concepts. In connection with a planned investment in a new SMT line, the company asked equipment suppliers for innovative process automation proposals.

Six placement solution manufacturers responded, and two made the short list after an initial evaluation. “The decision was not an easy one,” explains Nicki Holm. “We set up a comprehensive matrix with various weightings and considered all the pros and cons in minute detail. In the end we picked the Siplace solution, because it came out ahead in several categories, particularly because of the wide-ranging software package.“

The evaluation process ended with the decision to develop a totally new, production-based setup concept in cooperation with the Siplace team. The basis for the new development would be a SX line of the company with the latest software functionalities.

“Even during the first meeting, Danfoss expressed very precise and extremely ambitious ideas about the solution they wanted,” says Hubert Egger, product manager at Siplace headquarters in Munich. Danfoss project manager Nicki Holm, adds: “We placed great emphasis on avoiding any mistakes during product changeovers. The downloading of placement programs based on product barcodes we had implemented on our existing lines with great success already in the nineties. But now we also wanted to use this approach to control the conveyor rails and operate with floating instead of fixed setups. We also wanted to make sure that the setup changeovers would be executed error-free and would not affect the production performance. Consequently, the traditional approach with changeover tables was not an option for us.”

In February of this year, the company installed a line with five SX2 machines. Four of these hold two MultiStar placement heads each, and the last one is equipped with two TwinHead placement heads. The critical advantage of the MultiStar heads: they can switch placement modes (pick-and-place, collect-and-place and mixed) at the drop of a hat in order to meet the widest range of tasks.

The new line is initially scheduled to produce 36 different products in 100 versions. This means that the setup must be changed on average once per hour. Siplace realized quickly that it would have to apply the whole spectrum of its software expertise for this project. To meet the customer’s requirements, many current software tools had to be commissioned in a synchronized manner. At the end of the day, the engineers successfully combi- ned Stationwise Download, the compa- ny’s automatic conveyor width adjustment, Random Setup, Constant Tables and SiCluster Pro.

The Danish company has been using barcodes for a long time. They control the product process not only in the SMT field, but also to assign packages and product documents in the right language. In the SMT area, the system on the new line reads the barcodes on the PCBs and downloads the corresponding placement programs just like previously practiced on other lines. What’s new is that the SX machines also use this information to automatically adjust the conveyor rails.

When the first board of the next job enters the barcode reader located before the first placement machine, the system automatically requests the corresponding placement program and adjusts the conveyor rails accordingly. This means that the first machine has already switched to product B, while the remaining machines on the line are still finishing product A. With Stationwise Download, this process is executed for each machine individually as the new product travels through the line. As a result, the line never needs to be emptied, which gains valuable production time.

The setup changeover procedures were re- designed as well. As soon as the last board for job A leaves a machine, the X-feeder LEDs indicate which feeders are no longer needed for subsequent products and can be removed. The operator can now install the feeders for product C, i.e. the next product, in the open slots.

The entire process is coordinated via Random Setup. Nicki Holm explains: “The feeders can be installed in any available slot, and the machine recognizes automatically which feeder is located where. And since we associate each feeder with a particular reel in the offline kitting area, the placement machine knows exactly which component is available in which slot. This also enables them to eliminate any errors during the setup process.”

Some components are used in virtually all products. To make the setup process easier for these components, the team implemented a special solution at Danfoss: they are set up on so-called constant tables. These tables are not changed when a new setup is required. They are also arranged on one side of the SMT line. As a result, the changeover operations take place on only one side of the line, making for shorter walking distances and faster changeovers.

To let the line staff see what’s going on at all times, all lines are monitored via the Line Monitor. Large screens installed above the lines give reel and tray information, and whether the component supply is still sufficient. Operators also see early warning signals from anywhere in the facility and take appropriate action before the line comes to a halt.

The software and the customer-specific adaptations were installed in April and May of 2012. Today the line is fully operational, and the product changeovers function seamlessly. “We are very pleased with this jointly de- veloped solution. The new line is so efficient that we don’t just run the scheduled jobs on the new line, but also products from other lines. This provides us with much more scheduling freedom – an important factor in a plant that can normally plan only one shift ahead. The new solution gets us ready for the future.”

https://www.asm-smt.com/; www.danfoss.com/BusinessAreas/DrivesSolutions/

Mr. Lauber, you have called the new Siplace line at Danfoss Power Electronics in Denmark a trailblazing showcase project. What makes this project so special for you and your team?

This project demonstrates what solutions equipment manufacturers must provide for the future requirements in SMT production. It started with the customer’s request for proposals. The traditional questions regarding the placement performance or the component spectrum of the machines were totally secondary. Instead, Danfoss focused mostly on the question: How does the potential SMT solution support our specific concept with its lean, order-oriented and extremely high-mix production and clear delivery promises to our customers. Danfoss views its SMT production no longer as an isolated island, but as part of a value chain that must be optimized. As a result, the question posed to the Siplace team was not „What can your machine deliver“, but „How can you, being the experts, provide the best possible support for our processes with concepts, software and/or hardware?“

And how did your team respond?

The joint project team realized quickly that the coordinated interaction of hardware and software would make all the difference. To adapt the line to Danfoss’s specific requirements, we started out by combining existing Siplace options such as Constant Tables, Random Setup, Stationwise Download, and a whole lot more. The individual components are standard products, but the way we combined them at Danfoss is new and highly customized. In some cases we even programmed additional functions – something that equipment manufacturers will be increasingly required to do in the future. The line’s high automation based on barcodes improves and ensures the overall level of quality. The Random Setup feature, which allows our intelligent X-feeders to be installed in any available slot, may reduce the nominal machine performance by a few percentage points, but since it enables operators to set up the next product while the current product is still running, the overall line performance for all products increases significantly. It also demonstrates that today’s efficiency improvements are achieved by optimizing the overall process and not just parts thereof.

You stated that this is a highly customized Danfoss solution. How does it benefit your other customers?

The production concepts and processes of electronics manufacturers are becoming more and more specific. It might be, that only a few other producers will adopt the Danfoss concept down to the last detail. But electronics manufacturers realize that Siplace is a partner who can embed its placement solutions seamlessly into customer-specific process chains. We do this with our standard components, which we combine to achieve specific targets. Siplace also has the software skills and tools needed to make the necessary adjustment and integrate new functions. The fact that we recognized the rising importance of software very early really sets us apart from other equipment makers.

Dem Dänischen Unternehmen Danfoss Power Electronics ist es durch den Einsatz einer gut durchdachten Kombination verschiedener Setup-Lösungen gelungen, einen Produktwechsel an der neuen SMT-Linie durchzuführen, ohne dass der Herstellungsprozess angehalten werden muss.

Grâce à la mise en œuvre d’une combinaison bien étudiée de différentes solutions de Setup, il a été possible pour l’entreprise danoise Danfoss Power Electronics de réaliser un changement de produit sur la nouvelle ligne SMT sans avoir besoin d’arrêter le processus de fabrication.

Danfoss Power Electronics:

The Danfoss Power Electronics Division includes three business units: Danfoss VLT Drives, Danfoss Customised Power Electronics and Danfoss Inverters for Solar and Wind. The Division has supply chain, research and development centers in China, Denmark, the United States and Germany and a globalnetwork of sales offices offering customers high-quality, energy-efficient power electronics solutions.

Danfoss VLT Drives:

Danfoss VLT Drives supplies frequency converters for the electronic control of motors, which help customers save energy costs and improve performance. Danfoss VLT Drives is a global business with sales and service activities worldwide and with more than 40 years of experience within the VLT® frequency converter business. Danfoss has a leading global position in the HVAC, water, food and beverage segments and also on selected markets within a wide range of other industries, such as the chemical and textile industry, material handling and mining.