The future in automation is here at Ahlstrom Pumps.
It has been called a plant of the future, a foundry for the year 2020. Veteran foundrymen say they can't believe their eyes as they enter the facility."From the environment to the technology to the visual appeal, it is a benchmark for foundries to follow," said one foundryman. "It looks and feels unlike any foundry I have ever seen."
Although Ahlstrom Pumps shies away from calling its greenfield foundry and manufacturing facility in Easley, South Carolina, a benchmark for the industry, it doesn't deny that the plant showcases the company's manufacturing abilities.
"The technology and environment in our operation are critical to our production success as well as our visual appeal," said Plant Manager Alan Crawford. "But they are just two parts of the equation that helps us achieve the one-piece flow manufacturing and just-in-time delivery that are critical to our success."
From automatic guided vehicles to automatic pattern, corebox and casting retrieval systems and programmable "thinking" nobake molding lines, Ahlstrom Pumps invested $40 million to build its North American stainless steel and gray iron foundry and manufacturing facility (which ramped up in 1991) to service its growing North and South American customers. The one-piece flow philosophy has Ahlstrom producing one pump - from casting to assembly - at a time, limiting production runs of individual components to less than five pieces and eliminating inventory for mass assembly. When a pump order arrives, the plant starts production on it.
"Our foundry technology aims to produce the engineered pump casting at the lowest cost and highest flexibility," said Dale Libby, president, Ahlstrom Pumps, L.L.C. (North America). "We invested heavily in rapid throughput, as opposed to heavy inventory investments, to gain good customer service."
Although the 22-employee foundry produced only 540 tons of castings in 1997, which was down 20% from the previous year because of the Asian and South American economic crises, the manufacturing facility has continued to reduce throughput and lead times to a company benchmark of one week from order to casting and six weeks from order to finished pump.
Made in America
Ahlstrom Pumps is part of the worldwide A. Ahlstrom Corp., a 147-year-old privately-held Finnish firm ($2.6 billion in sales in 1998) that supplies systems and equipment to the pulp and paper industry worldwide and manufacturers specialty papers and converted products. In the late '80s and early '90s, the Ahlstrom Pumps division (with sales of $139 million in 1998), which serves process industries where difficult fluids and slurries are handled, "was growing rapidly in its targeted industry segments and saw a need to improve delivery and service capability," said Libby. In addition, the company wanted to broaden its customer base beyond the pulp and paper industry to food processing, metal and fertilizer industries. With 20% of its customer base already in the U.S., it became a logical place to expand manufacturing.
Although the firm has had success with its foundry-only operation in Karhula, Finland, it realized it had to reduce lead times and "wow" potential customers with just-in-time delivery to expand manufacturing to the U.S. and aggressively pursue new opportunities for growth.
"A technologically advanced foundry integrated with machining and assembly was going to provide us with reduced throughput and delivery times allowing us to rise above the competition," said Crawford.
Once the decision had been made to build a manufacturing facility to produce finished pumps, Ahlstrom headed to the Southeast U.S. and Easley, South Carolina, for a number of reasons.
"Easley offers a good labor force and competitive costs," said Libby. "Its location also allows us to be near our growing customer base." In addition, Easley provides easy access to the Port of Charleston for shipping, and the State of South Carolina provides tax breaks and incentives for companies building new facilities. In 1990, ground was broke, and in July 1991, production began.
Technology in Action
Ahlstrom's Easley plant is divided into two facilities - the 50,000-sq-ft foundry and the 80,000-sq-ft post-casting operation.
Within the foundry, two distinct molding lines - one nobake and one Replicast (a derivative of lost foam and investment casting, see sidebar titled "Replicast Molding") - operate side-by-side. Both lines produce stainless steel and gray iron castings, but the Replicast line is limited to smaller components (due to manual handling), while the nobake line produces castings up to 1300 lb. Typical stainless steel pump castings are volute casings and backwalls, and typical gray iron pump castings are bearing housings.
The heart of the nobake line is its computer-controlled production center and the automatic storage and retrieval system (AS/RS) for patterns [ILLUSTRATION FOR FIGURE 1 OMITTED]. The nobake team programs the molding line's control system for the patterns that must be pulled for production that day. When production begins, the AS/RS locates the patterns within its ceiling-high storage facility and sends them on a conveyor (properly spaced) for sand fill and compaction. One operator then controls the nobake mixer for mold filling, and the system automatically conveys the molds to the point that the second operator uses an automated clamp to extract the molds from the pattern box, coat them and send them through the curing oven. The molds then are conveyed to the storage area where a stacker crane brings them to the melt deck for pouring. The "thinking" nobake line controls the flow and patterns to ensure the correct production runs and also stores unpoured molds and cores for future production.
The nobake mold line's coremaking operation is strictly nobake (60% of its molds are cored). The coreboxes also are retrieved by an AS/RS that is connected to the production computer on which the orders for each day are input. Following automatic retrieval, the coremaker loads the day's boxes into the coreshooter for production.
On the nobake line, the foundry produces an average of 475 molds/month.
The Replicast molding line produces castings with thin walls (3 mm) and surface finishes between nobake and lost foam casting. This molding process, which is licensed by the Casting Development Centre, Sheffield, England, uses a polystyrene pattern (similar to those used in lost foam) and gating system that is coated with a refractory and invested in four layers of slurry and zircon and molochite sand (similar to investment casting). Unlike investment casting, Ahlstrom's molds consist of a single pattern, which is then transported (after being invested) to an oven for burnout of the polystyrene pattern. Invested molds are transferred to a lost foam flask line where each is placed in a flask and backed with loose sand prior to pouring.
On the Replicast line, Ahlstrom reaches 100 molds/month. Although these numbers appear low for a foundry of its size, Ahlstrom never sees a casting run greater than five pieces (because of one-piece flow manufacturing) and produces more than 2000 variations of its pumps. Even with one-piece flow manufacturing, the foundry still maintains a scrap rate under 4% without performing any casting rework.
Ahlstrom's pouring operation consists of four 1500-lb induction melting furnaces. The foundry uses a single 1-ton ladle to bottom-pour for both molding lines. The foundry melts up to 40 tons of stainless steel/month and up to 15 tons of gray iron/month. Its primary alloys in stainless steel are ASTM A890 3A, 1B, 4A and 5A and ASTM A744 CF-8M, CG-8M and CN-7M. The only gray iron grade it melts is ASTM A48 CL30B.
Keeping in line with its once-through manufacturing philosophy, Ahlstrom has simplified its shakeout system. To control airborne silica and emissions during cooling, the foundry developed two entirely enclosed shakeout systems - one for each line. The flasks from the Replicast pouring line empty directly into its shakeout, while the nobake molds are carried by stacker crane and transporter from the pouring deck to its shakeout. One hundred percent of the sand from the Replicast molding line is recycled. On the nobake line, Ahlstrom recycles 60% of its sand through its in-house mechanical reclamation.
After shakeout, the steel castings (70% of production and weighing up to 1300 lb) are collected by a monorail manipulator (a large mechanical arm), shotblasted and brought to heat treat before being sent to machining and assembly. The gray iron castings also are shotblasted, but proceed directly to machining and assembly. The melt, shakeout and heat-treat areas of the foundry are the only parts of the facility not air-conditioned.
"Once-through manufacturing has been very positive for our foundry and our product mix," said Crawford. "We are able to maintain a one-week production cycle from order to casting and a six-week lead time from order to finished pump."
To provide the finished pumps, Ahlstrom built an 80,000-sq-ft machining, painting, assembly and testing facility adjacent to the foundry. The firm believed that to maintain minimal lead times for finished products and just-in-time delivery, the waste involved in storage and shipping of components from plant to plant had to be eliminated. Once the castings have been shotblasted and/or heat treated, they are placed on pallets for transport to the machine shop.
At this point, the facility's automatic guided vehicle (AGV) takes control, which has eliminated the majority of forklifts from the operation. The AGV has been programmed with thousands of jobs, so that when the job number is entered into its system, it knows where in the facility to go to pick up its load (whether it be a motor, casting or finished component) and where to deliver it. The AGV uses laser sensors to guide itself around the plant floor and has sensors on its bumpers to avoid collisions.
The machine shop is composed of 25 vertical and horizontal CNC lathes and two machining centers from Burkhardt + Weber BW. Ahlstrom installed the machining centers in 1991 at a cost of $2 million, and these fully-automatic systems operate in conjunction with the plant's second AS/RS that houses the cast components waiting to be machined.
Before machining, multiple castings (depending on size) are assembled on a machining fixture and stored in the AS/RS. The machining center is preprogrammed for the day's jobs (it can run an entire weekend without supervision) and communicates with the AS/RS to bring the correct fixtures of castings to the machining system. The machining system then loads each fixture of castings and loads the job description from its memory to automatically retrieve the correct machine tool from the 276 tools it has available. These systems are responsible for 30% of the castings machined at Ahlstrom.
Once the cast components are machined, the plant paints, assembles and then tests the finished pumps for porosity via hydrostatic pressure, for functionality by running the pump, and for consistent wall thickness with ultrasonic equipment.
Pump Up the Volume
Currently, the foundry facility is only at 40% capacity because worldwide pump shipments have decreased due to the economic crises. However, as shipments increase and the foundry brings in good-fitting non-captive work, the unused capacity will lessen.
"If a long-term customer that fits into our product mix is interested in our capabilities, we will consider it," said Crawford. "Our technology gives us flexibility and the ability to increase capacity with a push of a button, so to speak."
Ahlstrom Pumps, L.L.C. North American Foundry
Easley, South Carolina
1998 Production: 540 tons.
Casting Data: Stainless steel and gray iron.
Markets Served: Pumps and pump components for the pulp and paper, food processing and machinery industries (95% captive and 5% jobbing).
Processes: Induction melting, Replicast and nobake molding, nobake coremaking, heat treat, machining, painting, assembly and testing.
Total Manufacturing Space: 130,000 sq ft.
Employees: 70 (22 in foundry and 48 in post-casting operations).
Staff Officials: Dale Libby, president; Alan Crawford, plant manager; Mike Kincaid, production manager; and Bill Nixon, metallurgist.
This molding process was developed by the Castings Development Centre (CDC), Sheffield, England, in the mid-1980s to provide steel foundries with the opportunity to garner the benefits of the lost foam casting process without the danger of carbon pick-up from the polystyrene patterns. Seven foundries in the U.S. and an additional 13 worldwide license the process in which polystyrene patterns are invested in refractory, slurry and stucco similar to the investment casting process. The process is utilized at both Ahlstrom foundries.
RELATED ARTICLE: Team-Based, Self-Management Provides Results
Besides implementing technology of the future at its Easley foundry, Ahlstrom has instituted a forward-thinking management system to run its plant.
The foundry and machine shop only have two supervisory personnel - one for each shift - resulting in a flat organizational structure with a lean management approach. Self-management is performed by employee process improvement teams that are formulated from the disciplines on the plant floor - molding, melting, cutoff/heat treat, machining, assembly, etc. This approach was developed by the Easley factory but is being adopted, in some ways, by other facilities in the Ahlstrom family.
Each team solves its own department's problems, makes decisions about technology, quality, productivity and process improvements, reviews team member performance, interviews new employees, and makes decisions on overtime and vacation time proposals. Each team has a $5000/year fund at their discretion to use within its department.
"We believe the best person to solve a problem is the person who works with it every day," said Alan Crawford, plant manager. "This creates job-enrichment by providing workers with the authority to say how things are done, and the problems are solved quicker."
Salaries at the Easley plant are based on a "pay for knowledge" approach to promote cross-training among workers. All the workers start at the same wage level and are expected to learn two jobs within their discipline, and raises are earned following an oral/performance test that examines the workers' proficiency in job knowledge, quality and safety. As a result, employees are encouraged to cross-train within their discipline and other disciplines within their department (foundry, machining and assembly). This allows Ahlstrom's employees to operate on a 4-day work week (Monday to Thursday or Tuesday to Friday) with two 10-hr shifts.
"The greatest benefit is that 'pay for knowledge' helps the employee learn the processes both before and after their current job," said Crawford. "As a result, these workers have a greater sense of awareness of what happens before a part reaches them and how their actions influence the manufacturing later in the process."
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|Title Annotation:||includes related articles|
|Comment:||The future in automation is here at Ahlstrom Pumps.(includes related articles)|
|Author:||Spada, Alfred T.|
|Date:||Aug 1, 1999|
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