No more system freeze-up

New carousel systems heat up production and repair parts distribution at boilermaker Weil-McLain.

By David Maloney, Associate Editor -- Modern Materials Handling, 5/1/2000

As any Purdue student can tell you, it is not unique to find a boilermaker in the state of Indiana. However, it is unusual to discover a boilermaker that actually makes boilers.

Weil-McLain is the leading cast iron boiler manufacturer in North America. Founded in 1881 by the Weil brothers in Chicago, the company produces 12,000-14,000 oil, gas, and electric boiler units a month during the peak heating season, and has experienced more than double-digit growth rates over the past several years.

To help accommodate this growth, Weil-McLain recently installed an efficient storage and retrieval system consisting of carousels that increase productivity in the production of both residential and commercial boilers, and in its extensive repair parts department.

This company knows a little something about the need for good heating systems. Located just a few blocks from Lake Michigan in Michigan City, Ind., the area is known for severe winters. Weil-McLain doesn't want to keep customers out in the cold either. Many dealers today carry only a limited stock of new boilers and replacement parts. They rely on the manufacturer to get them units and parts quickly, especially when a customer is without heat.

'Distributors are more inventory conscious and are stocking less,' says Don Christensen, associate director of physical distribution. 'They are putting the demands on us to ship more frequently and in smaller lots. It has changed the way we do business.'

The new carousels (Remstar ) now turn parts orders around in a day, where an old shelving system used to take several days at best, and often weeks to complete orders. Two shifts have been reduced to one in the parts area also, and double handling has been eliminated. Three times as many parts can be stored there as well, and best of all, the parts can be easily located.

Turning up the heat

Weil-McLain doesn't make all of the parts used to produce its boilers. As a result, the company receives large quantities of both component parts for manufacturing and repair parts at its docks.

As parts are received, they are recorded into the inventory management software either directly from a purchase order or by scanning each item as it arrives at the dock. The system produces an identification label that is either placed on the side of larger cartons that will head to bulk storage, or on the front of a bin container that will hold the parts in the receiving carousel. The receiving carousel stores parts that will be used in the manufacturing process, while a second carousel system located elsewhere in the facility stores repair parts.

Some parts also replenish a pre-pack station adjacent to the receiving carousel. Bins loaded with every conceivable small part fill the pre-pack shelving area. Workers pull from the bins to create kits, most of which are stored in plastic bags. Known as 'trim boxes,' these kits include screws, plugs, washers, and larger pieces that will make up an assembly designed for completion by the end user in the field.

The pre-pack system uses an automatic bagging machine along with workers who wrap larger parts in kraft paper. Just under 15,000 bags are packed every month. About 40% of these are routed directly to the assembly line where they will be added to outbound crates holding boiler units. The remaining 60% of the trim boxes are placed in bins for storage in the carousel.

'If we didn't bag the small parts, the carousel would have to make three or four more trips to retrieve all the needed parts,' notes Mark Smith, packing foreman.

Fewer trim boxes are actually built now than before the upgrade. This is because the parts are much easier to pick. Picking before involved more labor, so larger batch picks were performed that required more stock.

The receiving carousel has three pods. Each pod contains 44 stacks of 12 shelves with a 1,000 lb capacity each. Parts of every description are stored here.

They are first scanned with a hand scanner to alert the control system to the type and quantity of part being entered. The system determines the best storage location for the parts based on maximizing the cube space and signals the carousel to spin to that location.

'You won't see many empty shelves,' says Christensen. 'We max the space as much as possible.'

Weil McLain would have built a two-tier carousel if ceiling height were not a limitation. Instead, they designed the single tier for the maximum ceiling height. To reach upper shelves, the entire input/output station is mounted on a platform lift that rises automatically to the proper shelf height. A putaway light on the carousel indicates the shelf and bin assigned to the parts while the management system updates the inventory, noting the quantity and location for parts of each stock keeping unit (SKU).

Picking works similarly, but in reverse. As parts or trim boxes are needed for manufacturing, the mainframe prints out a pick list. A computer screen indicates whether there is enough of the desired SKUs in the system. If there is a lack, a discrepancy is noted. The system also instructs the operator to pull the correct carton sizes needed for the parts. There is room to stage anywhere from 6 to 32 boxes in front of the carousels, depending on carton size.

The carousel's three pods then begin to turn to the first picks and the station platform rises to meet the shelf height. A light comes on at each pod, signifying which shelf holds the needed item. The worker picks the item, scans it to confirm the pick, deposits it into the carton, manually checks off the written list, and clicks 'OK' on the computer screen to verify that the proper pick was made. The carousel then spins again, and the platform adjusts up or down for the next pick. This process is repeated until all items on the pick list have been pulled from the carousels.

Full cartons are loaded onto wooden pallets by hand. Once a stack has been achieved, a lift truck will take the cartons of parts to one of three places. The majority are sent either to a staging area near the line for use on assembly of boilers or transported to the finished goods storage area to be added as trim kits to already-assembled systems. Some picks are sent to replenish the repair parts carousel (see box below).

Weil-McLain produces 100,000 boilers each year. About 80,000 of these are residential units with the remainder for commercial applications. In the peak production season from July to December, 600 units are produced daily and the company ships on two shifts. The remaining part of the year the facility operates one shift.

Unlike some manufacturers that build to order, it is not practical for boiler companies to keep cold customers waiting. Instead, in-stock units are ready for shipment at almost any time. Most stock is turned over in 6-7 days. Since Weil-McLain knows the shipping schedule for the next 4-5 days, the manufacturing schedule is often focused on replenishing stock.

An on-site foundry casts the heavy iron blocks used as the basis for the boiler units. These are delivered to the line by lift truck. Overhead cranes move the blocks into position as portions are bolted together. The front and back castings are similar, the only difference in model size is the number of castings placed between them.

Units begin assembly on a non-powered roller conveyor. Various parts are delivered to the individual line areas on staging racks and pallets. Parts are added to the units based on a build order for that model, then pushed along by hand to the next station until completed. Residential units are built as a single unit. Commercial units, on the other hand, are built as knock-downs, meaning that due to their size, they are delivered in sections similar to parts of an erector set. In-field technicians will then assemble the pieces using the supplied trim kits.

The units are tested for leaks and crated. Crates are identified with a bar code that is scanned before putaway in pallet rack storage. Weil-McLain keeps about 4,500 units in inventory, representing 300 different models.

As orders are received and trucks arrive for shipment, the units are moved from the pallet storage to an outbound dock by lift truck. The carton bar codes are again scanned to verify proper selection.

The upgraded systems at Weil-McLain have increased productivity and allowed orders to be expedited more quickly.

'We no longer get calls from people trying to track their orders,' notes Christensen.

He also says that the carousels contribute enormously to the company's new efficiency. 'We are more productive, more efficient, and get more done with less effort,' says Christensen.

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