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New concept for modular shelving system By SSI SCHÄFER

Innovative material flow concept for modular shelving system

SSI Schaefer has developed an innovative automation concept for multi-storey modular shelving systems, which is now installed in the static small parts warehouse managed by the Development Parts Logistics department at Porsche Logistik GmbH. The ingenious combination of a small number of automation components supports the Porsche Logistik material flow concept and delivers long-term optimum throughput.

In line with its principle of ‘premium service for premium sports cars’, over the past few years Porsche has redesigned its spare parts supply logistics for customers and consolidated logistics functions for development departments at a single site.

The company’s new central spare parts warehouse at Sachsenheim was constructed in two phases between 2007 and 2010. A network of outlying warehouses which were increasingly hampering the efficient flow of material were closed down and the storage space and processes transferred to the 112 900 m² facility at Sachsenheim. This was the first point at which Porsche drew on the expertise of SSI Schaefer, which supplied the shelving systems for large and medium-sized parts. This project having been completed successfully, it was only logical to choose the Neunkirchen-based company to fit out the new distribution centre.

Photo by SSI SCHÄFER AG

So in February 2011 SSI Schaefer was awarded the contract to fit out part of the warehouse, destined to supply parts to Porsche’s development engineers. Every day 350 parts are transferred into the 10 000 m² storage facility and around 2000 components are shipped out. The warehouse stores small parts, medium parts in containers of up to 1200 x 800 mm (MT1), medium parts in containers of up to 1400 x 1700 mm (MT2), and bulky large parts (GT).

Between February and August 2011, SSI Schaefer set up three static pallet warehouses for medium and large parts. For MT1 parts there is a 12-aisle pallet store, with 10 aisles of eight levels and two aisles of seven levels. The MT1 narrow-aisle warehouse contains 5740 pallet storage spaces. Another 1438 spaces are available in the five storage levels of the 7-aisle MT2 warehouse. To store large parts there is a single-aisle pallet warehouse with 140 pallet spaces over five levels. “Thanks to the flexibility of our R 3000 shelving system, the layout of the new warehouse posed no problem,” says Arne Limper, Sales Group Manager for shelving installations at SSI Schäfer. “The key thing for the Porsche solution was to gear the storage areas towards a consistently efficient material flow, from the receipt of goods to picking and then loading the materials in outgoing goods.”

This placed particular demands on the processes in the small parts warehouse, which had to offer an intelligent solution. Sascha Drechsler, a planner at Porsche, sums up the criteria that the installation had to meet: “Compact but process-optimised, a low degree of automation to ensure flexibility, designed to cope with peak load but with the potential to handle future increased throughput.” The company therefore opted for a two-storey modular shelving system on a floating platform. The advantage of this configuration is that it uses the full height of the building while leaving the space underneath free for the processing of incoming and outgoing goods.

The two platforms, measuring 2000 m² each and at 5 m and 7.5 m high respectively, provide close to 9000 metres of shelf space for small parts containers weighing up to 15 kg. In total there are 42 000 containers in circulation. The challenge was to ensure the rapid and smooth movement of goods to and from the platforms. Both levels are equipped with transfer points for forklift-assisted goods movements, but these are simply an added extra for exceptional scenarios.

“For standard inward and outward transfer processes we had the option of using either a ramp system for trucks and lifting gear or a conveyor system and conventional lift systems,” explains Drechsler. “But neither was able to satisfy our material flow concept or growth strategy.” A ramp would have taken up floor space, so was quickly eliminated from consideration; and conventional lifts proved to be a bottleneck for the planned processes. “The small parts warehouse needs to cope with peak periods and allow for future increases in throughput,” says Drechsler. “This means fluctuations of at least +/- 20% Two conventional lifts would have been incapable of handling this. And three would have made the system too big.” Jürgen Kalkenbrenner, Sales Manager for automated complete systems at SSI Schaefer, explains another problem: “Conventional lifts are associated with unnecessary delays and tie up a lot of manpower. Everyone’s familiar with the situation: you’re waiting for the lift and when it finally arrives it’s full. For logistics processes, this just won’t do.”

During the implementation phase, the intralogistics specialists at SSI Schaefer and the planning team at Porsche Logistik developed a new and innovative conveyor solution which would soon become the “core of our small parts storage and picking processes”, as Drechsler puts it. The SSI Schaefer approach was to install a flexible automation solution for transferring goods to and from a conventional lift system. “This is the first step in automating a multi-storey modular shelving system,” says Kalkenbrenner.

Inward and outward processes are kept completely separate and generally follow the person-to-goods principle. Incoming goods are processed in the 2000 m² area underneath the platforms. Items for the small parts warehouse are repacked in containers and stacked on picking carts. A lift serves both platform levels and can be used for inward and outward transfer at the same time. Unlike basic lifts, the process is completely automatic. Warehouse personnel move the carts to a transfer station and press the button for the desired platform level. The process is then completed automatically without any further manual input.

On each side of the lift is an electric conveyor belt – one for loading carts and the other for discharging them. The belt conveyors also serve as a buffer for the next cart load. When the button is pressed the conveyor transports the loaded cart into the lift system. Quick-close doors seal the lift area and the two-column lift carries the cart to the selected level. At the transfer station the rolling gates open and the cart is ejected on the discharge side. “There is no need for anyone to be present to take the cart out of the lift,” says Kalkenbrenner. “In addition, the levels are continually supplied with inward goods containers.” At the same time, any carts on the other conveyor belt can be automatically transferred to the column lift with outgoing containers and carried to another level. “This saves precious time,” adds Kalkenbrenner.

A rotating table is installed at ground level to eject the roller containers. This table turns the carts and outgoing picking containers by 90 degrees before discharging them on to the outgoing conveyor. This ensures that the roller containers are correctly oriented below the platform structure so they can be consolidated in the outgoing goods area.

Efficiency calculations performed by Porsche Logistik show that the new system configuration is paying for itself after just a short time in operation thanks to the elimination of waiting times. “But this is really just an extra benefit,” says Drechsler. “The efficiency of the material flow was our top priority. The smart combination of conventional technology and additional automation components has produced a convincing system concept. It’s a process-optimised concept with which we can achieve guaranteed throughput and respond to potential growth.”

For further information visit www.ssi-schaefer.de