The recent installation of an InTouch scada and a Siemens 95U PLC system at the Mercedes Benz automotive parts storage plant in Pinetown, Natal, has been most beneficial in locating production stops almost immediately for quick and efficient correction.
The main objective of the scada/PLC system was to monitor the movement of automotive parts, from the intake area all the way through to the storage and dispatch areas. The functionality of the system allows its operators to locate any problems that may arise without any wastage of time, to correct the problem rapidly and to get the system back on line as soon as possible. Alarm indications alert operators to any problems which might arise and the system is able to generate comprehensive reports.
The system comprises a workstation situated in the main control room and a Siemens S5 PLC. Communication is via a Klinkmann S5 PG port driver. The workstation hosts the InTouch scada system and also runs MS Access, which generates the necessary reports. Security access is limited to a two-level password structure, one on operator level and one on supervisor level.
Receiving
The automotive parts received are unpacked from crates, sorted and placed into totes. The totes have an adjustable destination selector fitted onto the side. This destination selector can be set to send the tote to one of three levels in the warehouse or one of nine dispatch lines. The loaded totes are then placed onto one of four intake belt conveyors. These four Intake conveyors feed onto a single take-away belt conveyor. This conveyor is fitted with a pulse position indicator, which is used to generate locations or windows on the take-away conveyor.
Warehouse
At the warehouse a lift is installed to collect the totes from the receiving area and deliver them to one of three levels in the warehouse. A reading station placed at the incoming side of the lift section reads the destination selector mounted on the side of the tote basket and passes this information on to the lift, which then delivers the tote to the correct level.
On the outbound side, a similar process is followed. The warehouse operator loads the automotive parts into the totes and sets the destination on the destination selector - in this case the dispatch lines. The tote is then placed onto one of three outbound conveyors from where the lift collects the totes and places them onto the outbound conveyor.
Dispatch
A dispatch cross conveyor fitted with a pulse position indicator and a reading station transports the tote to one of nine gravity feed roller beds. The reading station then reads the destination from the destination selector and places the tote into the window on the cross conveyor. Associated with this window is a line number and when the window reaches the correct line, a pop-up table emerges and moves the tote off the cross conveyor onto the gravity feed roller bed.
Should the tote for some reason move out of its window on the cross conveyor, the tote will be marked as either too late or too early. From there the tote will move to a sorting line. Should a nonvalid reading be received from the reading station, the tote will be returned to the warehouse via a return conveyor. This conveyor merges with the receiving cross conveyor.
Reporting
The system reports on all alarms that occur. Reports are also generated on the amount of totes moving through the system, allowing the system operators to keep count of totes from the moment items are unpacked from their crates and sorted into appropriate totes, until their delivery to the warehouse or the outbound dispatch lines.
Benefits
The single main benefit of this control system is the enhancement in fault finding, especially from the scada point of view. The operator will immediately pick up when a fault has occurred and exactly where it has occurred. This means he will be able to attend to the fault faster and more efficiently.
Van Der Lande Industries South Africa contracted Streamworks, a South African leader in the field of supply chain management and industrial information technology, to design, commission and install the system. Streamworks took one month to complete the project, and provided onsite training for system operators in all aspects of report generation.
As well as designing and installing comprehensive turnkey solutions, Streamworks Group also provides a high level of technical back-up for its clients, including consulting, training and maintenance on all aspects of the systems it designs and installs.
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