Switch Assembly System: “Bacth 1” Is Not a Problem

Recently, Cosberg has created a switch assembly system capable of ensuring a production of 3,000 pieces/h, starting from 14 components and managing, in a fully automatic way, five product variants. But that’s not all: in order to meet the needs of maximum flexibility and time reduction, Cosberg has designed and manufactured a free-pallets in-line machine with a notable peculiarity: the possibility of producing the fateful “batch 1”.

For a company like Cosberg, which has been designing and manufacturing customized assembly systems for over 38 years, the concept of “tailor-made” is on the agenda. The solutions created can be considered prototypes (but with a reliability that is typical of industrial products) precisely because each order must necessarily be addressed as if it were a tailor-made suit, to be designed and manufactured to fully meet the customer’s needs. But in recent years, the tailor-made concept no longer concerns only realities such as Cosberg, but it is increasingly extending to mass products made by automatic machines, which must therefore adapt to the new high demands for high customization.

Plant for the assembly of switches: it ensures a production of 3,000 pieces/h, managing, in a fully automatic way, five product variants.
Plant for the assembly of switches: it ensures a production of 3,000 pieces/h, managing, in a fully automatic way, five product variants.

Customization is the new development trend

If in the pre-industrial era there was only craft production of individual pieces, which were specifically made – on order – based on the customer’s requests, everything changed with industrialization and we moved on to create batches of identical products in series, which were distributed to the mass without any kind of customization. For several years, however, there has been a trend reversal: customers have returned to ask for customized products and companies must therefore be able to supply them, if they do not want to lose competitiveness. This has led to an upset of industrial logic: no more stock in the warehouse, but “batch 1” production, which means producing only what the market requires and ensuring the supply of numerous variants of the same product. Not a small challenge, which has passed directly into the hands of machine manufacturers. Indeed, in order to be competitive in such a scenario, companies must have highly flexible production processes and therefore plants capable of ensuring fast production changes, maximum error reduction and high reliability.

3.000 pieces/h, 14 components and five product variants

For Cosberg, one of the first big “batch 1” challenges came from a customer who commissioned them to design and manufacture a system for switch assembly that would ensure a production of 3,000 pieces/h, starting from 14 components and managing, in a fully automatic way, five product variants. The solution, of course, had to be included in the customer’s production process, integrating with existing systems. In order to meet the needs for maximum flexibility and time reduction, Cosberg has designed and manufactured a free-pallets in-line machine with a notable peculiarity: the possibility of producing the fateful “batch 1”. In practice, the system was designed to assemble each model with no need for any mechanical intervention or adjustment. Production change takes place completely automatically: based on the order processed – or when the operator wants to make the change – the system autonomously activates or deactivates the stations (19 overall), depending on the model to achieve. Therefore, it is possible to have the machine carry out the simultaneous assembly of all product variants.

The assembly process steps

For most products, the steps involved in the assembly process can be summarized as follows. The first component is a subgroup (main body) fed by a contact molding and assembly machine that is placed before the Cosberg plant; this subgroup is then placed on an accumulation system equipped with a camera that checks the correct body composition. Following this, three levers are inserted in the main body, each in a precise position with respect to the contacts already present in the subgroup. Most of the components are fed by MoxMec ADER electro-resonant autodistributors using the patented piezoelectric technology. Handling and positioning of the pieces are entrusted to patented electromechanical pick and place arms, which in addition to offering considerable savings in the use of compressed air, ensure maximum precision and great flexibility. The process continues with the greasing of a contact. The greasing operations are performed by devices that perform greasing by means of a pressing plate pump, complete with pressure stabilizer and volumetric dispenser. The following phase sees the feeding of a moving contact which is checked and, if it conforms to the model in production, positioned on the previously greased part. A small rotary table assembles another subgroup, consisting of an element in which a spring is inserted. A pick and place arm picks up this last subgroup, inserts it and hooks it to the switch body, making sure that the spring rests perfectly on the appropriate seat of the mobile contact. A plastic top cap is also mounted on some product variants, complete with spring button and slider. Obviously, for the models that do not include the cap, the stations used for these assembly steps are automatically excluded.

The perfect combination of flexibility and efficiency

In general, the numerous and different springs that make up this product are fed by ADER-type electro-resonant autodistributors, complete with disentangler, and then shot with compressed air along a flexible tube that takes them to the special insertion head, which accurately positions them. Throughout the process, the presence and correct positioning of levers, contacts and other elements are checked by special devices, which – based on the outcome of the check carried out – enable subsequent actions or discard the piece. The final product is then tested and checked to ensure the suitability of each individual piece. This key activity makes use of special devices placed at the end of the assembly cycle. The first performs a programmable number of main body break-in cycles. Below, two special mechanisms, equipped with a load cell, operate the side levers and control the spring resistance. Once released, the levers return to position. At the same time, a contrast device descends from above to prevent the internal contacts from moving while the levers are moving. For each piece assembled and checked, the system records the maximum force values detected. Finally, “contacting” is made and a programmable number of ON/OFF cycles with switching and continuity control is performed. In the last step, all the pieces are marked with two latest generation 3D lasers. Finally, with a view to Ready To Run, the plant – 11 m long – will be installed in a maximum of five hours and will start producing as early as the next day. The success of this solution is based on a perfect combination of maximum flexibility and total reduction of machine downtime necessary for production changes. Another prerogative appreciated by the customer is the great system efficiency, which has made it possible to reduce ramp-up time. This efficiency can be maintained over time thanks also to the help of the new Cosberg monitoring system, which allows you to supervise productivity even remotely and thus to better manage any assistance and maintenance interventions.