SMA Solar

For the production of its inverters using the kanban system, SMA Solar Technology AG relies on powerful and efficient storage systems from Hänel in its components store.

Carbon-neutral production – the factory of the future

SMA Solar Technology develops, manufactures and sells solar inverters for photovoltaic systems which convert the direct current generated by solar cells into alternating current as supplied by the grid. Inverters for all module types and all capacity ranges – from small roof-top installations for the home to giant solar parks – are manufactured at the main branch in Niestetal near Kassel.

Since the company was founded 29 years ago, this globally active enterprise has experienced continuous growth and in 2009 achieved sales of EUR 934 million. SMA is represented outside Germany by branches in 12 countries and currently employees over 4,000 people.

Last year SMA in Niestetal inaugurated the world's largest and carbonneutral inverter factory. By doing so, the company took on a leading role in environmental protection and has set the trend in terms of carbon-neutral industrial production. The main pillars of their policy here were energy efficiency and the use of renewable energy sources. With efficiency measures in the production process and an energy-efficient building concept, energy requirements have been reduced to a minimum. The power still required is drawn from renewable sources.

„Lean production”

SMA also sets new standards with the exceptionally high level of flexibility realized by the company in its manufacturing. "Lean production" at SMA is called "SMArt flow". The production philosophy of lean, no-waste manufacturing at SMA is based on the kanban material flow concept first developed by Toyota in the seventies. Today this concept impacts on almost all sectors of industrial production where articles are stored and handled. In contrast to the classic push-type manufacturing system, kanban implements a pull-type system which is oriented purely on consumption. Small-scale, decentralized feedback loops replace the central scheduling department. This makes kanban suitable for all companies using articles with a high level of predictability and usage frequency, which enables a certain degree of standardization.

Lothar Weix, Head of THT production at SMA, explains: "With the kanban system of logistics, only the amount of material that is actually needed is transported to the assembly position. That way our workers can concentrate fully on the assembly work. Only when one material container is empty do they take material out of another container. The empty container is then filled up immediately with the relevant material and made available to the assembly line again. All SMA production steps are coordinated according to the "SMArt flow principle" and can be adapted flexibly. There are no fixed walls, fittings or conveyor belts on the actual production floor. "This means we are able to adapt our production lines and workstations at any time to the respective order situation and to customer requirements ", adds Lothar Weix.

Lean-Lifts and Rotomat

vertical carousels in the kanban system 

The intralogistics at SMA have to function smoothly. Klaus Bornkessel, Head of Logistics in the electronic production department explains: "Our order structure can change within days. So a modular, decentralized storage system is the most useful for our material flow system. As it was important for us to have, among other things, the reliable, time-proven chain drive system of the Hänel storage systems, we decided to opt for the flexible and modular Lean-Lift storage units and Rotomat vertical carousels when we expanded and modernized our storeroom in 2004." With their vertical lift technology, the 12 compact Lean-Lifts provide a storage area of about 1,200 m² on a minimal footprint of about 100 m². The simple and reliable storage technology from Hänel offers a number of advantages over other storage systems:

• height-optimized storage creates up to 60 percent more storage volume
• simultaneous "goods to man" order picking with short access times thanks to parallel operation by multiple users at different lifts and carousels
• ergonomic retrieval height, no ladder-climbing – no risk of accidents
• decentralized storage – the two Rotomat carousels holding production tools right on the shop floor are one example
• easy scalability thanks to the modular design
• flexible choice of modular storage compartment size within the shelves thanks to height-optimized storage
• protection from dust and light as a result of the closed construction
• ESD protection with special, anti-static finish
• the favorable cost-benefit ratio of the vertical lift modules and vertical carousels as compared with miniload systems guarantees a quick ROI (return on investment).

At the present time, SMA has 12 Lean-Lifts and 7 Rotomats which are used to store and retrieve some 12,000 electronic components according to the FIFO principle.

Bornkessel explains why: "All Lean-Lifts and Rotomats work extremely reliably. Corresponding customer service, efficient monitoring and diagnostic systems along with the short-term availability of service technicians (within four hours of call-out) were key criteria for us when choosing a system supplier", said Klaus Bornkessel.

The multifunction carriers of the Rotomat vertical carousels offer customized, variable compartments for the different components of the SMA inverters. The carriers can be adapted easily to changing requirements. For example, there are carriers with punched holes into which intermediate shelves and movable dividers can be slotted, or drawers with different heights.

In the Lean-Lift, the inventory items are assigned to container types of six different sizes. First the allocation of bins to lift shelves is defined; this roughly divides the inventory items according to the later industrial processing stages. The assignment of actual storage locations, however, is automatic. This ensures that retrieval runs smoothly and continuously, and frequent changing between lifts is avoided.

ESD protection throughout

ESD is the abbreviation for "Electrostatic Discharge". It often occurs as a result of friction. Generally this is a relatively harmless phenomenon. If a person walks over a rug, for example, and static electricity builds up, then the person touches an object, the static is discharged through an electrical spark. What people experience as a mere tingling or crackling sensation, however, can be sufficient to seriously damage electronic components or even destroy them. Usually ESD damage on electronic systems goes unnoticed until the customer finds the end product doesn't work. To prevent damage from occurring in the first place, the Lean-Lifts and Rotomat carousels are designed with ESD protection. Any static is discharged in a controlled way and new build-up prevented.

Storage management with Hänelsoft

All business processes at SMA are transparently integrated into the existing SAP business software for production, sales and inventory control. As a general rule, standard ERP software with a module for storage management is not adequate for applications where business procedures place special demands on automation, and special technology such as barcode scanners and electronic dispatch equipment need to be integrated. And where there are specialist requirements such as the control of vertical carousels, an "addon" to ERP software is usually necessary. This is why both the production orders and the transport orders for storage and retrieval operations are entered by barcode in the SAP job pool.

The individual Lean-Lift and Rotomat controllers are already equipped with extensive storage management functions and so can be incorporated effortlessly in the IT environment of SMA. All material handling operations are based on identification of all the articles by barcode. Scanners at all lift stations eliminate the need for time-consuming entries and prevent input errors. Replenishment and picking orders for production materials are created by the scheduler at the central computer and transferred online to the HänelSoft storage management system that manages the Lean-Lifts and Rotomats. This simple and user-friendly storage management software is integrated in SAP's higher-level IT system.

Klaus Bornkessel explains: "Complex processes are made simple with operator-friendly solutions that use barcode scanners and input terminals right at the Lean-Lifts and Rotomats. This gives us a consistently transparent software landscape, enabling us to process up to 5,000 transport orders as well as pick and put operations in up to 18 shifts per week, and to track and trace movements transparently. Moreover, the customizing of the HänelSoft storage management software and the e-mail modules in the SAP order processing system was easy to do."

Conclusion

Optimization of the material flow - from incoming goods through warehousing to provisioning of the assembly line at SMA - was achieved efficiently with Hänel's flexible and modular storage systems. Klaus Bornkessel emphasizes: "Flexibility and reliability of the storage systems have top priority for us, both in terms of the way they are used and the processing of incoming orders. Next to this, the transparency of the operations is a key aspect and fundamental to automated storage management. These are requirements we impose not only on the functionality of the inventory control system, but also on the overall system design of the storage technology. With the Lean-Lifts and Rotomats from Hänel we have been able to substantially reduce our stocks and consequently our planning and control costs." "Our versatile microprocessor control systems enable easy integration into customer-specific logistics systems ", adds Joachim Hänel, CEO of the intralogistics supplier Hänel.