The best of aluminum melt shops: Modern Casting asked aluminum melting experts to tell us what it takes to be a "prize" aluminum melt shop. Is it technology? is it engineering? This article reveals what we were told and profiles facilities that have earned the title of "Best Aluminum Meltshop" from their peers.
To be the best in a given field, a firm must separate itself from the crowd. To determine the best in aluminum melting, MODERN CASTING asked experts to nominate plants that have implemented cutting-edge technology, engineering or business philosophies to make their firm the model for which all others are judged.
But how can an aluminum metalcasting facility be targeted as one of the best? Numerous characteristics must be taken into account to define an ideal aluminum melt shop.
Dan Groteke, Q.C. Designs Inc. maintains that a good operation starts with good planning. He said the melt facility must be matched to serve the existing molding lines or match plans tot expansion in the near future. A large, impressive melt department may not reach its full potential if the rest of the metalcasting facility is not equipped to handle it. Becoming too ambitious with melt department designs could result in large losses in the future.
"You will normally want enough capacity to serve the anticipated maximum demand, but excess capacity is costly in more ways than you can imagine," Groteke said. "Beyond the initial capital cost, excess capacity costs money in inventory costs, energy costs, melt losses and maintenance costs."
Groteke pointed out that matching the melt department to a metalcasting facility's needs and capabilities is important for small- to medium-size shops, although larger plants can benefit from it as well.
"Careful planning is required for all sizes because those considerations are primary to any operation," he said, "There is nothing more expensive than to operate a melter at 10% of its rated capacity or to have excess capacity sitting in an idle furnace."
Once the size of the melt department has been matched to fit the rest of the operation, it is time to focus on process flow and philosophy.
"There is probably a best way to melt aluminum, but there are other considerations that go into that as well, including how many alloys you are pouring, what the alloys are and what the production requirements are coming out of the melt shop," said David Weiss, Eck Industries. "But the key characteristics of any melt shop, regardless of volume, is that it has to produce good metal before you pour."
The foundation for building an ideal melt department is making sure to start with quality material and making sure it maintains its integrity throughout the process. To do that, Weiss said a firm must have the tools necessary to analyze the melt as well as properly clean and degas it. Then, a metalcaster must find an efficient way to transport the molten aluminum to the mold without adding gas or inclusions back in, thus negating the work already performed.
"One of the things we do for premium castings is we melt and move the metal into a homing crucible, which also is the crucible that we pour out of," he said. "Make the alloy additions and clean and degas in the holding crucible so you can pour directly into the molds with out having to move it again." Weiss also offered some key points to ponder:
* are you doing fine final processing (grain refining and silicon modification) as close to the molding station as possible? Are you pouring soon thereafter?
* what's your starting mix of ingot and scrap? Are you alloying your own material?
* are you assessing the economics of your melting methods depending on your product mixture?
* how many different alloys are you reeking? If you melt more than one, are you taking more precautions to control your chemistry. All of the above points are important to consider when developing an ideal aluminum melt shop. But to reach the next level, many experts agree that a change in philosophy also is necessary.
"Frankly, the company should be quality certified, either through ISO 9000 or 14000 or QS," said David Neff, Metaullics Systems Co. I.P. "In principle, that would say it all. That means you have control over the sources, quality and chemistry of your raw materials. It means you have specific process standards and you continually educate and train your melt room people in the process standards."
According to Neff, that philosophy has to come from the attitude of top management, and he believes it should be focused on three areas--cleanliness, orderliness and education.
"Another subtlety that often goes ignored is emphasizing that safety and cleanliness goes hand-in-hand with quality," he said. "And that's attitude. If management's attitude instills in the operators the need for following procedures, safety and cleanliness, it will result in better quality. You need to have constant surveillance, preventative maintenance, process auditing, education/training and a feedback system instead of a top down managerial dictate in terms of what gets done."
A feedback system can provide other benefits. When employees feel free to share their ideas, an effective problem solving network is in place.
"You can get an incredible amount of information from the guys who are doing the work and are free to speak," Neff-said. "There is and can be a managerial dictum that is fairly dogmatic and says you will do it my way, but it shouldn't thwart individualism."
And above all, Neff suggests to start with the basics.
"It's paying attention to detail and basics and having an open mind without ruling out any possibility," Neff said. "Safety, education, training, princess control and understanding melting and handling are vital. A lot of people don't want to pay attention. But it's the basics, its common sense and it's fostering an atmosphere where there is a tree interchange of ideas.
The following pages feature two aluminum metalcasting facilities that have earned the distinction of being the "Best Aluminum Meltshops" from their peers. They are recognized because they have been able to incorporate many of the above characteristics into their operation and have taken the extra step to reach the next level.
Ryobi Die Casting USA, Shelbyville, Indiana
Over the past five years, Ryobi Die Casting USA, Shelbyville, Ind., has been making a push for increased efficiency. In the late 1990s, the firm added a second facility adjacent to the existing one to help accommodate the six reverbatory furnaces, 42 holding furnaces and 42 diecasting machines it had at the time. The new facility was patterned after the existing one, which had proven successful for Ryobi. Everything, from the building lay outs to a return conveyor system to furnace modifications, was carefully planned out. Once ready, half of the melt department's equipment was moved to the new' building.
"Our plants are laid out in a rectangular shape," said Lynn Funk. Ryobi's melt operations manager. 'The melt shops are on the for end of the building, and it flows from left to right. We start with melt operations and then go down the corridor to the diecasting area."
Ryobi has a total of 650 employees, 27 of which are needed to run the six gas-fired reverbatory furnaces from Lindberg/MPH, Riverside, Mich., and the 42 holding furnaces ranging in size from 4,000-7,000 lbs in both plants. Five reverbs are equipped with recirculation and discharge pumps and plans are under review for the purchase of a new furnace by the end of the year to further increase efficiencies.
In Ryobi's two plants, automation is used to eliminate the human element from the melting operations. Scrap and returns are pushed by a conveyor system into the hearth, where they are melted and checked for chemistry. The conveyor system collects returns and feeds them onto a main conveyor, which then feeds into a pump well, eliminating the need for manual handling. Other returns are added through the back of the furnace and fed into the bath as quickly as possible.
In the furnace, one pump removes molten aluminum and places it into ladles, while another is located in the open wells at the back to circulate an air current throughout to homogenize the bath and create an undertow to draw scrap castings into the hath sooner.
Ryobi has been operating a lean philosophy for the last 3 1/2 years that Funk said dictates, "you put into the furnace what you take out."
"It has been fabulous," he said. "It has helped us reduce our cost of" gas and helped our furnace efficiency."
After the molten aluminum has been pumped into a ladle, a fork lift truck picks it up and delivers it to one of the 42 holding furnaces that feed the 42 diecasting machines. Three furnaces and ladles are used in each plant with two forklift trucks making continuous loops between the furnace and diecasting machines.
Funk said when business is good, six reverbs are running at the same time. Ryobi hit its peak production in 2002 when it melted 230 million lbs. of aluminum, in 2003, it melted 220 million lbs. To produce its A380 aluminum, Ryobi uses the "little bit of this, little bit of that" philosophy by mixing together various types of purchased aluminum sows with its returns and blends this with silicon and copper "on the fly."
"That's something that not many other facilities have the ability to do," Funk said.
Ryobi's planned addition to the melt department is a 150,000-lb. melter equipped with a regenerative combustion system. The firm is considering the purchase after a modification to an existing furnace proved successful.
In 1998, Ryobi added a 120,000-1b. conventional cold air melting furnace. The unit is equipped with two wall-fired burners and a gross input of 21.57MM BTU/hr., a preheat hearth for sows and alloy elements, and side scrap and recirculation wells. To increase efficiency in natural gas usage, Ryobi modified the furnace by removing most of the combustion system and replaced it with a regenerative combustion system, which utilizes a pair of burners that cycle to alternatively heat the combustion air or recover and store the heat from the furnace exhaust gasses. While one burner is firing, the other is exhausting the furnace gases. Exhaust gases pass through the furnace body and into a media case that contains refractory material.
The refractory media is heated by the exhaust basses, thus recovering and storing energy from the flue products. When the media bed is fully heated, the burner currently firing is turned off and begins to exhaust the flue products and the burner with the hot media bed begins firing. Combustion air passes through the media bed and is heated by the hot refractory. Air preheat temperatures within 300-500F of the furnaces are achieved, resulting in high thermal efficiency.
With the modifications, the BTUs required to melt and hold a pound of aluminum was cut in half (dropping from 2,356 BTUs/hr. to 1,150 BTUs/hr.). Gross input dropped from 21.57 MM BTU/hr. to 15 MM BTU/hr. and the inch rate increased from 11,000 lbs./hr, to 12,250 lbs./hr.
Bremer Manufacturing Co., Elkhart Lake, Wisconsin
When Bremer Manufacturing Co., Elkhart Lake, Wis., made the decision to switch completely to electric furnaces 15 years ago, it made a strategic decision to reconfigure its melting area as well.
The decision was to move the melting furnaces from the end of the molding line to a location closer to the pouring line. The result was tighter process controls.
The firm originally made the decision to go electric so it could minimize the gas absorption in the melt that is inherent with gas or oil furnaces. But as long as new equipment was being added, Bremer decided to move the furnaces so the molten aluminum would spend less time being exposed to air while transporting it to the pouring line.
"Before, when we were melting at the end of the molding lines, we would tap the metal and bring it over in large ladles. As a result, we had to superheat the metal," said Glen Laehn, Bremer's president. "With having the molten metal adjacent to the molding line, we now have very good control over the metal. We are able to pour at a consistent temperature and maintain it."
The firm started the conversion by adding a 1,200-lb. electric furnace from Thermtronix Corp., Adelanto, Calif. Since that time, Bremer has steadily been adding equipment and now has 16 2,300-lb. capacity melting furnaces (from Thermtronix), the newest of which is three years old.
"We started out with smaller furnaces," Laehn said. "This has been an evolution for us, and the 2,300-lb. has become the staple now. We are sort of compact and limited by size, but our design puts the furnaces adjacent to the molding line."
Bremer's furnaces feed five green sand molding lines used to produce castings for combustion engine components and for use in the architectural lighting industry. Bremer runs two shifts each day, reloading the furnaces at the end of the second shift and recharging when they are 2/3 empty. The facility remelts all of its metalcasting facility scrap, but none of the machine scrap, with ingot and scrap mixed 60/40 into the melt.
The furnaces are brought up to temperature an hour before pouring starts for the first shift and are recharged throughout the day to keep enough molten metal in supply for second shift. Bremer, which is primarily a Tier 2 supplier but does some work as a Tier 1, has 120 employees, 30 of which are dedicated to the melting and molding. Four molding lines are typically run during a shift with one molder for each line as well as two employees pouring for each line and two more in shakeout.
The metalcasting facility melts about 375,000 lbs. of aluminum a month.
As part of the tight process controls that Bremer keeps, degassing is done with argon by a manual lance, although Laehn said that future plans may include investing in a mechanical degassing system.
Following degassing, the molten metal has a short trip to the pouring lines, which are no more than 15 ft. away. As the molds come off the molding machine, they are placed on a rolling conveyor system that snakes through to the shakeout area.
Year Founded: 1984 Metals Cast: A380 aluminum. Employees: 650. Monthly Throughput: 20 million lbs. Casting Weights: 4-55 lbs. Markets Served: Automotive. Melting/Holding Furnaces: Six gas-fired reverbatory furnaces and 42 electric holding furnaces ranging from 4,000-7.000 lbs. Year Founded: 1937 Metals Cast: 319, 356, A356 and 535 Employees: 120 Monthly Throughput: 375,000 lbs. Casting Weights: Less than 30 lbs. Markets Served: Commercial lighting and combustion engine. Melting Furnaces: Sixteen 2,300-lb. capacity melting furnaces.
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|Date:||Sep 1, 2004|
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