Chain Reaction

Jan. 1, 2001
Warehouse control system helps centralized distribution center ship anywhere, anytime.

Chain Reaction

Warehouse control system helps centralized distribution center ship anywhere, anytime.

Here’s a challenge for a warehouse management system: guarantee shipment of any of 1.2 million SKUs of chemicals to anywhere in Europe. First, however, consolidate three existing warehouses into one facility.

Combining its Sigma, Aldrich, and Fluka warehouses promised to give Sigma Aldrich Chemie GmbH several advantages. "We needed the ability to offer customers the optimal service available through a central delivery system," said Peter Schuele, director of the company. "Plus, we needed to handle a 15 percent increase in orders. Witron Logistics helped us combine our warehouses into the new European Distribution Center in Schnelldorf, enabling us to meet the increased demands and our customers’ needs.

"We chose Witron because of its experience with a similar-sized project, the European distribution center for Baxter Healthcare Corporation," continued Schuele. "In particular, we were impressed with their refusal to shorten the implementation time frame. Given the complexity of the project, they would not compromise the implementation."

Expanding SKUs

Sigma Aldrich offers 120,000 products for laboratories, pharmacies and universities. Each is available in either solid, liquid or gas form. Each chemical, though, may have more than one lot or batch number, which the warehouse system considers to be a new item.

Each product also comes in a range of sizes, from milliliters to huge vessels. Add up all these variations, and it totals 1.2 million SKUs that a warehouse system must manage.

A complication to the inventory system, however, is that these products are not distributed to end users in the conventional manner. The chemical products are grouped, according to regulations, into their specific hazardous classifications. This organization affects storage, handling and transportation. Many products, for example, must be stored and transported in controlled-temperature areas.

Thus, the distribution center includes manual, freezer zone, and miniload systems. Nedcon Lagertechnik delivered the racking. Witrons’ subcontractor TGW in Wels, Austria, was responsible for the AS/RS cranes and the general mechanical installation including roller and belt conveyors, lifts and turntables.

The manual storage area temperatures are kept at 4 degrees C. The automatic freezer unit, with two AS/RS cranes in the deep freeze section, maintains a temperature of -18 to -20 degrees C. Both storage areas hold 25 percent of the products.

The remaining products are situated in the miniload AS/RS system. The zone is divided into six temperature zones ranging from 5 to 25 degrees C separated by fire-resistant walls.

The SAP host system generates, in cooperation with the AS/RS system, 2,200 orders per day. This results in an average handling capacity of 3,000 to 3,600 orders in an 8- to 10-hour working day. With 18 picking work- stations, it’s possible to achieve a total capacity of 6,000 picks per hour.

Parcels are packed in any of 36 workstations. About 30 parcels per workstation per hour can be handled. The outbound capacity of the warehouse is an average of 5,400 parcels.

The 600 x 400 millimeter tote units were designed and developed with Utz, located in Schuettorf, Germany. Each tote is divided into 24 single, bar code defined "bin" compartments. Because of this relatively simple scheme, the system easily achieves the requested picking performance.

Bar codes identify each product throughout the warehouse and distribution center.

Out of a virtual box

Following the severe hazardous-goods regulations, the SAP system splits the incoming orders into logical partial orders. This information transfers to the WCS system, which generates "virtual bins" for shipping units and picking orders. About 1.5 virtual boxes correspond to one pick order, which accounts for the difference between the number of customer orders and picking orders.

On orders from the Witron Order-Picking-System (OPS), AS/RS cranes transport bins to picking stations, where an order is then picked. Afterward, confirmation is sent to the SAP system, which arranges for printing of the transport documents. If needed, the OPS can also be easily integrated into a manual pallet-picking system. With the use of scanners and scales, picking order errors have been minimal.

The transformation has been a success. "We are able to meet our customers’ delivery requirements," said Schuele. "For one customer in Italy, for example, order cut-off time is 5:30 p.m. When the order data are transferred to the WCS, the internal logistics process is triggered and the order arrives in Milan the next day. SCF

System at a glance

Here’s a closer look at material flow and working areas:

Small parts storage

• Automatic storage and retrieval system (AS/RS).

• Goods-to-man principle, about 10,000 square feet divided into six storage areas according to hazardous goods classifications.

• Nineteen crane aisles for 982,500 storage locations.

• Double deep storage capacity of 88,000 totes, each tote containing 24 bins.

• Nineteen automatic cranes: 1,600 transactions per hour.

Manual storage area

• Temperature controlled area of more than 10,000 square feet with eight different zones.

• Orderpicking by man-to-goods principle, with specially designed RF-guided picking cars.

Pallet warehouse

• 230 locations for bulk storage, 118 locations for flammable goods, and 200 locations for catalogs and documentation.

Sorter, buffer system

• Sixteen sorter-buffer systems each with 14 locations.

• 175 picking bins per hour; in-sequence and on-call can be equalized by the buffer.


• Six inbound stations can also be used as packaging stations. Capacity is 75 SKUs per hour.

Control stations

• Each of the three control stations, which can also be used as picking stations and are equipped with a spotlight system, can handle 150 SKUs per hour.

Picking stations

• 16 picking stations with spotlight system; three of them can be used as control stations.

• 150 order lines per workstation, per hour.

Packaging locations

• At each of the 32 packaging locations (of which six stations can be used as receiving stations), 30 packages per hour can be prepared for dispatch.

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