New England Foundry
For more than 75 years, New England Foundry, Inc., has manufactured woodstoves for home use. In recent years, with increasing energy prices, George Mathison, president of New England Foundry, has seen sales triple. This dramatic increase in sales has made it even more difficult for George to maintain quality in all the woodstoves and related products.
Unlike other companies manufacturing woodstoves, New England Foundry is only in the business of making stoves and stove-related products. Its major products are the Warmglo I, the Warmglo II, the Warmglo III, and the Warmglo IV. The Warmglo I is the smallest woodstove, with a heat output of 30,000 Btu, and the Warmglo IV is the largest, with a heat output of 60,000 Btu. In addition, New England Foundry, Inc., produces a large array of products that have been designed to be used with their four stoves. These products include warming shelves, surface thermometers, stovepipes, adaptors, stove gloves, trivets, mitten racks, andirons, chimneys, and heat shields. New England Foundry also publishes a newsletter and several paperback books on stove installation, stove operation, stove maintenance, and wood sources. It is George’s belief that the company’s wide assortment of products is a major contributor to the sales increases.
The Warmglo III outsells all the other stoves by a wide margin. The heat output and available accessories are ideal for the typical home. The Warmglo III also has a number of outstanding features that make it one of the most attractive and heat-efficient stoves on the market. Each Warmglo III also has a thermostatically controlled primary air intake valve that allows the stove to adjust itself automatically to produce the correct heat output for varying weather conditions. A secondary air opening is used to increase the heat output in case of very cold weather. The internal stove parts produce a horizontal flame path for more efficient burning, and the output gases are forced to take an S-shaped path through the stove. The S-shaped path allows more complete combustion of the gases and better heat transfer from the fire and gases through the cast iron to the area to be heated. These features, along with the accessories, resulted in expanding sales and prompted George to build a new factory to manufacture Warmglo III stoves. An overview diagram of the factory is shown in Figure 5 .
The new foundry uses the latest equipment, including a new Disamatic that helps in manufacturing stove parts. Regardless of new equipment or procedures, casting operations have remained basically unchanged for hundreds of years. To begin with, a wooden pattern is made for every cast iron piece in the stove. The wooden pattern is an exact duplication of the cast iron piece that is to be manufactured. New England Foundry has all its patterns made by Precision Patterns, Inc., and these patterns are stored in the pattern shop and maintenance room. Then a specially formulated sand is molded around the wooden pattern. There can be two or more sand molds for each pattern. Mixing the sand and making the molds are done in the molding room. When the wooden pattern is removed, the resulting sand molds form a negative image of the desired casting. Next, the molds are transported to the casting room, where molten iron is poured into the molds and allowed to cool. When the iron has solidified, the molds are moved into the cleaning, grinding,
and preparation room. The molds are dumped into large vibrators that shake most of the sand from the casting. The rough castings are then subjected to both sandblasting to remove the rest of the sand and grinding to finish some of the surfaces of the castings. The castings are then painted with a special heat-resistant paint, assembled into workable stoves, and inspected for manufacturing defects that may have gone undetected thus far. Finally, the finished stoves are moved to storage and shipping, where they are packaged and shipped to the appropriate locations.
At present, the pattern shop and the maintenance department are located in the same room. One large counter is used both by maintenance personnel to get tools and parts and by sand molders who need various patterns for the molding operation. Pete Nawler and Bob Bryan, who work behind the counter, are able to service a total of 10 people per hour (or about 5 per hour each). On average, 4 people from maintenance and 3 people from the molding department arrive at the counter per hour. People from the molding department and from maintenance arrive randomly, and to be served, they form a single line. Pete and Bob have always had a first-come, first-served policy. Because of the location of the pattern shop and maintenance department, it takes about three minutes for a person from the maintenance department to walk to the pattern and maintenance room, and it takes about one minute for a person to walk from the molding department to the pattern and maintenance room. After observing the operation of the pattern shop and maintenance room for several weeks, George decided to make some changes to the layout of the factory. An overview of these changes is shown in Figure 6 . Separating the maintenance shop from the pattern shop had a number of advantages. It would take people from the maintenance department only one minute instead of three to get to the new maintenance department. Using time and motion studies, George was also able to determine that improving the layout of the maintenance department would allow Bob to serve 6 people from the maintenance department per hour, and improving the layout of the pattern department would allow Pete to serve 7 people from the molding shop per hour.
1. How much time would the new layout save?
2. If maintenance personnel were paid $9.50 per hour and molding personnel were paid $11.75 per hour, how much could be saved per hour with the new factory layout?