Romac Industries Foundry Div., Sultan, Washington.
Metal Cast: Ductile Iron
Markets Served: Water Works Industry (couplings, rings, flanges, etc.)
Melt Tonnage: 625/month
Meltshop Employees: 15
Now in its 29th year, the foundry division of Romac Industries is in the process of completing a massive foundry modernization and expansion project. In the course of the project, the meltshop, which makes strictly 65-45-12 ductile iron for Romac's olivine sand molds, has expanded in total space from 3000 to 9500 sq ft. According to General Manager Bart Walker, the shop previously held a 1-ton/hr coreless induction furnace running four days a week in two 10-hr shifts. "It served us well," he said, "but we needed more metal." Demand was ramping up, and modernization was necessary to keep pace.
Although the modernization is continuing, the $2 million meltshop (designed by Venetta Engineering and Romac project engineer Bill Brown) was completed in January 1997. All charge material is stored indoors and is serviced by a 7.5-ton bridge crane. The crane brings the metal to either of two 12,000-lb VibraPro vibratory hoppers on the trim deck. The hoppers are on load cells to provide a digital readout of weight as the charge is built. When the charge is complete, the PLC-controlled hoppers advance on rails to the furnaces, where the charge is deposited.
The new furnaces are two 6-ton ABB IFM4 coreless induction units run on a 4000 kW Twin Power shared-power supply. This arrangement allows Romac to batch melt, since the power can be shared between the furnaces in any desired amount. Thus, meltshop employees can charge one empty furnace while holding and tapping from the other.
Walker said that batch melting has two main advantages for Romac. "First, we get increased electrical conversion efficiency," he said, explaining that for a coreless induction furnace, the greatest electrical efficiency is achieved when the unit is melting, not when it is holding. "Second, we no longer need to preheat our charge because we're adding it to a dry furnace." By the time the metal begins to liquify in the furnace, any moisture in the scrap has been evaporated.
"The power-sharing ability of our furnaces now allows us to pour continually," Walker said. "Previously, we had to wait for the single furnace to come up to temperature. This is like the difference between hopping and walking." In addition, the furnaces themselves are more energy-efficient than the old melter, and Walker said that kWh consumption per lb of metal melted has improved about 15%. They are also flexible: "Our local power company called and requested that we change the ramp-up time for full furnace power from 2 sec to 20 sec, and all that was required was a simple program change to the furnace PLCs," Walker said.
Hot metal is tapped from the furnaces into 1500-lb tundish ladles for treatment and moved on a monorail loop. The metal is then transferred to pouring ladles and post inoculant is added manually (although this step will soon be automated). The pouring ladles then go either to the new Disamatic Mark V-B vertical flaskless molding line or to the cope and drag/Beardley & Piper Matchblowmatic flaskless mold pouring area. At the Disa line, a unique pouring arrangement has been adopted using two ladles pouring at intervals along the line, helping to maximize efficiency. However, the final step in the melthop modernization will be the September addition of an ABB Press Pour automatic pouring furnace with a Selcom laser control system.
Melting operations are controlled from an office above the melt deck housing an ABB melt processor, which provides graphic and digital data on charge weight, furnace temperature and power levels. The furnace power supply is located in a vault beneath the melt deck. Romac has also invested more than $100,000 in its metal and sand labs for quality control.
Though only operating at 40% of its total 17,500 ton/year melting capacity, Romac's productivity has improved so much that the foundry now runs only one shift, and is considering expanding into more jobbing markets with its free shift. Walker also noted a paradigm shift at the foundry. "Previously, the metal had to come to the molds; if the molds weren't ready, the metal would wait," he said. "Now, the molds have to come to the metal, and the metal must be ready." And it is. 'The furnaces are so reliable that we get to concentrate on the more elusive aspects of making good castings."
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|Title Annotation:||iron foundry; America's Best Induction Meltshops|
|Comment:||Romac Industries Foundry Div., Sultan, Washington.(America's Best Induction Meltshops)(iron foundry)|
|Date:||Jul 1, 1997|
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