Controlling processes

“We’re only able to influence quality within the processes we run ourselves – and that’s why Festo manufactures all of its electronic components in-house”, explains Martin Wittner, manager of Festo’s electronics division. In accordance with the kanban concept, ultramodern manufacturing equipment and well trained skilled workers produce all of the electronic components used in the valve terminals, controllers and drives manufactured by Festo.

The entire production environment at the electronics manufacturing division has been fully optimised. Air-conditioners supply air in cleanroom quality for the 3,000 square metre production area, and ensure constant temperature and humidity levels. Cleanroom class 100,000 can even be attained in SMT manufacturing through the use of special air filters.

To a great extent, production of electronic components at the electronics manufacturing division in Ostfildern-Scharnhausen, Germany, is fully automated. Roughly 30 % of overall production output is accounted for by finished products which are shipped directly to customers. The other 70 % is comprised of semi-finished goods which Festo assembles into its own products, for example valve terminals. A brief look behind the scenes shows how PCBs are assembled and quality tested under cleanroom conditions.

Surface mounted technology
The three SMT production lines (surface mounted technology) play a leading role in the electronics manufacturing division and are capable of placing from 30,000 to 80,000 components per hour depending upon component shape. The systems insert SMD components such as integrated circuits, transistors, capacitors, resistors etc. into the PCBs which have been printed using solder paste. Four 12-position turret heads grasp miniature electronic components by means of vacuum, and insert them into the PCBs at precisely the right position at breathtaking speeds. A twin-head placing unit inserts the larger components. After the PCB has been fully assembled, it’s sent along to the soldering oven where the components are soldered in a nitrogen atmosphere at a temperature of 260° C. An AOI (automatic optical inspection) system then checks the PCBs with assembled SMD components for faults – if possible, quality problems are corrected in production, and corresponding corrective measures are implemented within the running SMT manufacturing process. The flexibility of the SMT production lines is a great advantage: They’re changed over to different products up to three times a day – very quickly.

Through-hole mounting ensures stability
Highly qualified skilled workers come into play where automated production is not possible. This applies to plug connections on the PCBs which are used directly by the customer. The components are inserted into the PCBs manually, after which they are automatically soldered. An additional through-hole mounting technique involves press-fit plug connectors. These processes provide the plugs with additional stability, but they’re also more costly. 60 Festo employees work in the PCB assembly department. They’re universally trained and can be deployed anywhere in the production department – wherever their skills are required at the time.

Testing strategy
With its 11 highly qualified specialists (electronics engineers, electrical engineers and skilled workers), the test equipment fabrication department is responsible for implementing Festo’s testing strategy which specifies 100 % inspection for every product. A combination of various test procedures including AOI, ICT and function tests ensures that only top quality products are shipped to our customers.

Raising the curtain on kanban
The production process is based upon the kanban principle: Only those goods are produced which are actually required or needed by the customer. The continuity of the kanban concept begins with the customer and ends with the supplier. High inventory levels tie up considerable sums of money. The primary goal of the kanban system is to alleviate this capital intensive situation. In addition to this, throughput times and manufacturing lot sizes are reduced. This results in a flexible production sequence that can react quickly to changing quantity requirements, and demonstrates improved product availability in comparison with conventional PPS systems. Material requirements at upstream processes are more uniform, and employees have a more consistent workload as a result. The more evenly distributed workload brings product quality into the foreground to an ever greater degree, and scrap rates diminish. Festo also takes advantage of kanban in valve terminal assembly in Esslingen-Berkheim, and at its production facility in St. Ingbert-Rohrbach. Launched many years ago as a pilot project in electronics manufacturing, the implementation of the kanban concept now enjoys widespread success at Festo.

Courtesy of  Festo