Metalcaster of the Year: Dotson Iron Castings: Dotson's commitment to capital improvements and integration of new technology in a jobbing environment made it this year's choice for Foundry of the Year.

In order for Dotson Iron Castings, Mankato, Minn., to come closer to its goal of becoming the world's most automated jobbing metalcasting facility, it had to walk away.

In one recent automation project, the iron casting firm wanted to upgrade its pouring operation on a new green sand molding line to reduce variation and labor requirements. The answer was a "walk-away" pouring system with an automated pouring ladle--a bit unconventional for a low-volume casting facility. Incorporating the automated equipment into the facility's production took some work, ingenuity and significant capital investment, but the end result was a system that stabilized pouring, reduced physical labor and could be taught easily to a new operator.

The automated pouring system is one of several investments that have led MODERN CASTING to name Dotson Iron Castings as this year's Metalcaster of the Year. Other investments--many the first of their kind in North America--include the replacement of a third automatic molding line and mold handling system, and the addition of four automated grinding machines.

Walk-Away Pouring

The 130-employee gray and ductile iron shop has evolved its business philosophy as industry trends have evolved. For instance, in the mid-1980s, it streamlined its operations to keep a focused attention on casting design and manufacturing. With this design philosophy and good customer relationships in hand, the firm set its attention inward toward capital investment in the 1990s and 2000s.

One such investment is a Roberts Sinto Econopour automated pouring ladle. At first, an automated pouring system seemed like a long shot for the jobbing shop. The company wanted to reduce variation and physical labor in the pouring department, but automated pouring ladles had only been used efficiently in high-volume facilities. As far as Dotson knew, this type of tool did not exist for low-volume production.

The firm initially tried to work through the problems that existed with bottom-pour ladles, but couldn't achieve the operational standards it wanted. Eventually, through its partnership with its supplier, Dotson was introduced to automated pouring equipment that, with slight modifications, was a natural fit to meet the production requirements at the metalcasting facility.

The pouring ladle employs a virtual nozzle that makes sure the metal is poured at the same distance from the mold at all times. The ladle is mounted on a carriage with a fixed arm and is controlled on multiple axes, which allows it to rotate, move up and down, move toward and away from the mold, and move between molds on the line.

"So much of the variation is now taken out of our process," said Dennis Dotson, Dotson's president. "We now can pour mold-to-mold within 0.5-0.75 lbs. (227-340 g), which eliminates almost all over and under pours."

Operators of the $2 million pour system are needed only to program new pouring sequences and oversee the operation. The operator fills the ladle every eight minutes, completes required quality assurance testing, watches the first couple of molds being poured and then walks away to help out around the rest of the shop. What was once a highly-skilled job that required significant experience is now a job that can be operated by newly-hired personnel. Yield improved nearly 5% with the new molding line and 2.5% over the entire plant.

Keeping Track of Molding

Dotson's new automatic pouring ladle caps off a molding line that features a new molding machine, mold conveyor and turntable, which were installed in 2004. The new line can make 120 molds/hour on core jobs and increased Dotson's capacity by more than 15%. When the firm went to three shifts, capacity was increased by 40%.

Dotson's newest molding line is fully integrated with several PLCs coordinating all of the activities from molding to shakeout. For instance, if the molding machine operator notices that a mold was formed incorrectly, he or she can tag the mold on a computer screen and the automatic pouring will skip it as it comes down the line. This communication throughout the line, along with production data collection and retention, helps eliminate unnecessary scrap.

Daily Grind 

While grinding is typically an integral part of a job shop's material flow, Dotson had outsourced it since 1983 for economic reasons. In the early 1990s, the company decided to look at automatic grinding in an effort to take as much back-breaking, accident-prone labor out of the process and possibly open the door for bringing it back in-house.

In 2002, the firm purchased and installed two Roberts Sinto Barinder automated grinding machines--the first of their kind to be installed in the U.S. Two additional machines have been purchased since. Programming for each grinding job is performed by the operators on the shop floor.

"When we started looking for an automation solution, we realized it was becoming much more difficult for our subcontractor to recruit employees to grind," said Jed Falgren, vice president of manufacturing. "Fortunately, in addition to a more employee-friendly grinding process, we have better consistency and quality and have been able to bring the operation back into our company. We've also resolved a few customer issues with the new machines."

Over the last four years, grinding production has increased more than 60% at Dotson Iron Castings. Changeover time with the new grinding machines is just five minutes, and tooling can be created for as low as $300.

Employee Input

Dotson's recent molding/pouring line and grinding investments are examples of investments the company makes on a continual basis. In the 1990s, Dotson made a commitment to continually invest in its facility with a program referred to as "$10,000 projects." Through a management/ employee-driven process, the firm constantly seeks and identifies ways to increase the efficiency of its manufacturing process. Dotson involves employees in choosing any equipment that costs more than $10,000 to ensure the money is well spent and results in the purchase of equipment compatible with current metalcasting processes. To date, more than 100 of these projects have been generated, with some in the initial discussion stages and many more implemented throughout the company.

"It's hard to put a dollar sign on the pride people have in their work, but eventually it's going to pay off. You know it's there and you know it helps," said Jim Headington, process quality manager.

In 2000, Dotson used a $10,000 project to re-examine its furnace charging system. Previously, the charge system consisted of two people moving scrap with wheelbarrows to preheating and charge buckets. From there, the scrap entered two induction furnaces to produce 70 tons of iron a day. Determined to eliminate this punishing, inefficient labor, the firm chose to implement a robotic arm to perform the heavy work.

The new furnace charging system, which consists of a manipulator with a large magnet on the end, is operated by one person in an air-conditioned booth.

The magnet picks up charging material and feeds it into a vibratory weight conveyor. Then the material is dumped into preheating and charging buckets on a rotating turntable. Today, the system easily supports more than 100 tons a day.

Employees fit the new charging system into both the plant operations and the physical layout of the plant. Their input produced a maximized layout that allowed one person to perform the job, with extra time to help on the melt deck.

For More Information

"The Dotson Co.: Simplified Manufacturing and Casting Design," L. Swenson, MODERN CASTING, Oct. 2001, p. 32-35.

Dotson Iron Castings Mankato, Minnesota 

Year Founded: 1876.

Metals Cast: Austempered ductile iron, ductile iron, gray iron.

Casting Process: Green sand--horizontally parted molding.

Size: 110,000 sq. ft.

Monthly Melt: 1,800 tons.

Casting Size Range: 1-75 lbs.

Value-added: Engineering and design, painting, pattern shop, machining, finishing and material testing.

Employees: 100.

Dotson iron Castings Named Metalcaster of Year

MODERN CASTING selects its Metalcaster of the Year based on the recipient of the annual American Foundry Society Plant Engineering Committee's Plant Engineering Award. This award is presented annually to a North American metalcasting facility that has demonstrated engineering expertise to advance the capabilities of the metalcasting industry. Dotson Iron Castings, Mankato, Minn., was chosen for its commitment to automation, which is evident in its replacement of a third automatic molding line and mold handling system and four new automated grinding machines.

Past winners of this award have included Hayes Lemmerz Montague, Montague, Mich.; John Deere Foundry, Waterloo, Iowa; International Truck and Engine Corp.'s Waukesha Manufacturing Facility, Waukesha, Wis.; Neenah Foundry Co., Neenah, Wis.; Mercury Marine-Mercury Castings Div., Fond du Lac, Wis.; and American Cast Iron Pipe Co., Birmingham, Ala.

Qualifying a customer

When casting purchasers choose a metalcasting facility to supply cast components, they have certain requirements that they expect the casting facility to meet in order to be awarded a contract. This helps the purchaser find the best fit for its own company's business agenda.

Dotson Iron Castings feels that perfect fit should be a two-way street. Just as Dotson must meet certain guidelines set out by its customers, it seeks out customers that fit its own guidelines with the purpose of establishing long-standing, valuable customer relationships.

In order to keep long-term strength through loyal customers, Dotson has made a goal that the new customers found in 2006 are still customers in 2010. When casting purchasers are shopping for bids, Dotson keeps several questions in mind in order to determine if the job and customer are a good fit for a long-term relationship.

Things to consider include whether there are value-added opportunities with the prospect, whether the prospect is currently purchasing offshore castings or might in the future, or whether the prospective customer's market is growing Dotson also considers the organization of the customer itself. Does the customer have lean manufacturing, six sigma or other programs? Does it regularly visit its suppliers? Is it a company that's growing?

We know that customers will have high expectations of their suppliers," said Todd Nelson, vice president of sales. "It is equally important that we set a high expectation of the relationship. With a strong positive relationship, win/win solutions become the standard."

Shannon Kruse, Associate Editor