Cell-based shoe production plant – Special automated guided vehicle (AGV)
Construction of a flexible system for shoe production.
Construction of a shoe-production automated plant based on manufacturing methods inspired by Lean Production principles.
– less labour needed;
– remarkable increase in production;
– waste reduction;
– improved operators’ working conditions.
This application, which is in operation at a shoe manufacturing firm belonging to a major Group working in the couture fashion industry, is based on the use of two of our new special AGVs, each designed according to our Customer’s own specifications. As the first cell-based shoe production line in the world, the application was patented by our Customer. Changing market conditions and the need to manufacture very high quality shoes urged our Customer to develop this plant, which features great flexibility of adaptation to the production of lots that are constantly changing and characterised by very small quantities. The products to be manufactured are placed on RFID-tagged racks. The different processing steps are divided into groups where the individual operators’ cycle times are similar to each other. The racks are handled inside the individual groups by means of roller conveyors which advance the racks from one operator to the next. Two special AGVs at both ends of the roller conveyors make it possible to feed the racks to be processed to the roller conveyors and to download the processed racks from them. Each AGV features a motorized belt system for loading/downloading the rack. As the rack has a different orientation direction in each roller conveyor, a rack-rotating system is fitted too. The entire system is operated through a specially-developed software program residing in an industrial computer as located in the main electrical switchboard. In the rack-preparation area the operator loads the different components needed to produce the shoes into the racks by matching the rack code to the processing cycle required by the specific type of shoes. The two special AGVs automatically carry the rack identified by the system only to the roller conveyors which are part of the processing cycle determined by the operator. Once completed, the rack returns to the rack-preparation area, where the operator downloads the finished product, thus making the rack available for a new production. The settings of the handling of the AGVs are based on the Customer’s requirements. Given the limited space available, the AGVs move along the same path in both directions in this application. Each AGV’s path has a max linear development of app 50m and a max speed of 55m/1’. Each AGV can carry racks having a max weight of 150kg and it can move along paths covered by operators and lift trucks too thanks to the use of safety laser scanners. The system used for automatically driving each AGV consists in a magnetic adhesive tape applied to the floor which follows the desired layout and makes it possible to rapidly change at any time the path that the AGV is to follow in order to reach the different stations. This allows great flexibility in adapting to any changes in the layout of the stations inside the facility over the years. No building works are needed in order to equip the facility with the AGV driving system. As the production rates are expected to be quite demanding, each AGV comes equipped with a last-generation lithium battery having a small size and weight to the benefit of the AVG’s overall dimensions and actual carrying capacity. The autonomy of this type of battery is not comparable to that of gel batteries, thus ensuring the AGV’s operation for two work shifts on end, i.e. 16 hours of operation a day. The plant is also equipped with a recharge station for each AGV. At the end of the work shift the AGV returns to the recharge station and automatically starts a recharge cycle by accessing the relevant battery charger. Our AGV applications come always supplied with the relevant EC conformity certifications enclosed.