TB wood's simplifies gating, pouring.Lean manufacturing Lean manufacturing is the production of goods using less of everything compared to mass production: less human effort, less manufacturing space, less investment in tools, and less engineering time to develop a new product. is a customer-driven, continuous quality improvement activity designed to maximize customer value. Its goal is to create the shortest end-to-end value stream with the highest quality, lowest cost and shortest delivery, ultimately leading to maximum utilization of available capital and capacity. Implementation of lean in the aggressive iron metalcasting facility requires a perspective of the entire operation, particularly casting engineering, since decisions made here directly affect molding, melting, pouring, cleaning and all other casting operations. TB Wood's, Chambersburg, Pa., is a gray and ductile iron Ductile iron, also called ductile cast iron or nodular cast iron, is a type of cast iron invented in 1943 by Keith Millis[1]. While most varieties of cast iron are brittle, ductile iron is much more ductile, as the name implies. metalcasting facility that produces castings for power transmission equipment on automatic horizontal molding machinery. It has been engaged in the implementation of lean manufacturing throughout all metalcasting operations since 2001. An integral part of this program has been the reengineering of a large number of gray iron castings that has led to substantial yield increases (casting weight a weight that turns a balance when exactly poised. - B. Trumbull. See also: Casting divided by pour weight), quality improvements and reductions in cleaning costs and scrap. To increase tonnage TONNAGE, mar. law. The capacity of a ship or vessel. 2. The act of congress of March 2, 1799, s. 64, 1 Story's L. U. S. 630, directs that to ascertain the tonnage of any ship or vessel, the surveyor, &c. and reduce customer lead times without added capital investment, it was necessary for the metalcasting facility to produce more saleable sale·a·ble adj. Variant of salable. saleable or US salable Adjective fit for selling or capable of being sold saleability or US castings with its existing equipment by reducing scrap associated with sand and slag inclusions and better utilizing available pattern plate real estate. TB Wood's investigated a pouring technique that eliminates the need for conventional molded runners, down sprues, filter prints, risers and other gating system elements, which frees up pattern plate room for additional castings. The process incorporates a tapered ta·per n. 1. A small or very slender candle. 2. A long wax-coated wick used to light candles or gas lamps. 3. A source of feeble light. 4. a. refractory refractory Material that is not deformed or damaged by high temperatures, used to make crucibles, incinerators, insulation, and furnaces, particularly metallurgical furnaces. insulating sleeve with a ceramic foam Ceramic foam is a tough, plastic-like foam made from ceramics. It is similar to Kevlar.The foam is made of aluminum oxide, a common high-temperature ceramic, but gets its extraordinary insulating powers from the many tiny air bubbles within the material. filter insert. The insulated in·su·late tr.v. in·su·lat·ed, in·su·lat·ing, in·su·lates 1. To cause to be in a detached or isolated position. See Synonyms at isolate. 2. sleeve can function both as a pouring cup and as a feeder feeder abbreviation for self-feeders. Used in feeding groups of animals at intervals of several days. Feed has to be dry and comminuted so that it will run down the spouts from the hopper into the troughs. during solidification so·lid·i·fy v. so·lid·i·fied, so·lid·i·fy·ing, so·lid·i·fies v.tr. 1. To make solid, compact, or hard. 2. To make strong or united. v.intr. . The filter traps furnace furnace, enclosed space for the burning of fuel. There are many kinds of furnaces, the type depending upon the fuel and the use to which the heat produced within it is put. Most familiar are the furnaces used in the heating of buildings. and ladle slags and other inclusions and controls the flow of metal into the cavity. Incorporating this direct pouring method into its operations led to greater pattern utilization at TB Wood's, resulting in the need for half as many molds to make the same number of castings. Casting Reengineering Program TB Wood's produces castings that range in weight from 3-10,000 lbs. (1.36-4,536 kg) with an annual tonnage of finished castings in excess of 12,000 tons. Its automatic molding equipment includes a 20 x 24-in. mold (51 x 61-cm) (Fig. 1) with a 10 x 10-in. (25.4 x 25.4-cm) flask flask (flask) 1. a laboratory vessel, usually of glass and with a constricted neck. 2. a metal case in which materials used in making artificial dentures are placed for processing. , horizontal, high-pressure green sand molding machine (Woodworking) A planing machine for making moldings (Founding) A machine to assist in making molds for castings. See also: Molding Molding with maximum casting weight of 150 lbs. (68 kg). Other automatic molding equipment and a flask molding line also are employed. A group of similar gray iron castings was identified to be reengineered for TB Wood's new pouring technique. Each of these castings was produced with conventional molded runner systems on the automatic 20 x 24-in. (51 x 61-cm) high-pressure green sand molding machine. In-line pressed parts were used for filtration. Because of the limits of the sand delivery and molding and pouring systems, efforts to produce additional or larger conventionally molded castings on this equipment without risking run outs had not been met with success, and scrap rates for this group of castings were unacceptable. Initially, the firm examined ways to improve the conventional runner system and sand risers, and pressed parts were replaced with ceramic foam filters without further modification of the runner system. In 2002, a pouring method using filters and refractory sleeves was evaluated to determine if additional sound (slag-free) castings could be produced without run outs on the existing 20 x 24-in. (51 x 61-cm) pattern plates. Original Casting Design Previously, this method for pouring had been restricted in automatic molding because ram-up or insertion of the pouring unit from the top of the core is normally impractical im·prac·ti·cal adj. 1. Unwise to implement or maintain in practice: Refloating the sunken ship proved impractical because of the great expense. 2. or not possible. But incorporating a reverse-taper pouring unit that can be inserted through the bottom of the cope made the technique an option for TB Wood's automatic molding operations. A 25-1b. (11.3-kg) gray iron hydraulic gear pump A Gear pump uses the meshing of gears to pump fluid by displacement. They are one of the most common types of pumps for hydraulic fluid power applications. Gear pumps however are also widely used in chemical installations to pump fluid with a certain viscosity. housing was a typical casting for this program (Fig. 2). Originally, with conventional gating and sand risers, only two castings could be produced in each mold without excessive run outs as a result of cope lift. The system was non-pressurized, with a sprue sprue, chronic disorder of the small intestine caused by impaired absorption of fat and other nutrients. Two forms of the disease exist. Tropical sprue occurs in central and northern South America, Asia, Africa, and other specific locations. choke (jargon) choke - To fail to process input or, more generally, to fail at any endeavor. E.g. "NULs make System V's "lpr(1)" choke." See barf, gag. that included an inline pressed part horizontally placed in the runner bar for filtration and two sand risers. The gating ratio was 1:3.5:1.2:2 (sprue area: runner area: ingate area: riser contact area). Produced two-on, the total casting weight was 50 lbs. (22.7 kg), the total pour weight was 97 lbs. (44 kg), and the yield was 51.5% (50/97 = 51.55). Scrap from all causes with this design was 13.5%. Pouring Redesign The hydraulic gear pump casting was redesigned to incorporate reverse-taper pouring units. A single unit capable of containing 5.9 lbs. (2.67 kg) of molten metal and incorporating a 20 PPI (1) (Pixels Per Inch) The measurement of the resolution of a monitor or scanner. For example, a monitor that is 16 inches wide and displays 1600 pixels across its width would have a resolution of 100 ppi (1600 divided by 16). foam filter was used to pour and feed four castings on one pattern plate (Fig. 3). Produced 4-on, the total redesigned casting weight was 100 lbs. (45.4 kg) and the total pour weight was 117 lbs. (53.1 kg). The yield increased to 85.4% (100/117 = 85.47), and scrap from all causes was reduced to 5% (Table 1). Flow simulation of the modified layout confirmed that the new technique had not adversely affected turbulence turbulence, state of violent or agitated behavior in a fluid. Turbulent behavior is characteristic of systems of large numbers of particles, and its unpredictability and randomness has long thwarted attempts to fully understand it, even with such powerful tools as within the mold (Fig. 4). Although 20 lbs. (9.1 kg) of additional metal was now poured into the same-size flask, 30 lbs. (13.6kg) less was poured into the feeding system--the portion of the casting that contributes most to the ferrostatic forces that cause cope lift. The facility now can produce twice as many castings in the same flask without run out. Cost Savings Analysis A conservative cost analysis shows that the metalcasting facility obtained a substantial return on their pouring investment. To protect the confidentiality of the firm's cost structure, industry average cost figures for molten metal in the mold and for molding costs were used in the trial cost savings analysis in Table 2. All other figures are actual values from the trial described above. While the cost of the pouring units increased the cost of the feeding system by $0.42 in this application, the resulting $3.17 savings per casting resulting from scrap reduction and yield improvement returned the increased feeding system cost several times over. In total, TB Wood's converted approximately 30 castings to its new pouring method and achieved significant yield improvements while continuing to produce sound castings. One casting of particular interest was originally configured con·fig·ure tr.v. con·fig·ured, con·fig·ur·ing, con·fig·ures To design, arrange, set up, or shape with a view to specific applications or uses: 4-on. Through the use of the technique and a 4 x 2 splitter core, it was configured 8-on, which increased the yield to 84% from the original 47%. (Fig. 5). Table 3 summarizes the yield improvements attained on five additional castings. Svetlana Dodik-Pelja is a foundry process engineer with TB Wood's Inc., Chambersburg, Pa. Andy Adams Andy Adams (May 3, 1859 – September 26, 1935) was an American writer of western fiction. Andy Adams was born in Indiana. His parents, Andrew and Elizabeth (Elliott) Adams, were pioneers. As a boy he helped with the cattle and horses on the family farm. is a product application manager for ferrous ferrous (fĕr`əs), iron in the +2 valence state. Containing or having to do with iron. The difference between ferrous and ferric is the number of valence electrons they contain (ferrous contains two and ferric contains three), which filtration products with Foseco Metallurgical met·al·lur·gy n. 1. The science that deals with procedures used in extracting metals from their ores, purifying and alloying metals, and creating useful objects from metals. 2. Inc., Cleveland. For More Information "Pressure Drop Characteristics ef Iron Filters," A.C. Midea, 2001 AFS A distributed file system for large, widely dispersed Unix and Windows networks from Transarc Corporation, now part of IBM. It is noted for its ease of administration and expandability and stems from Carnegie-Mellon's Andrew File System. AFS - Andrew File System Transactions (01-042). Svetlana Dodik-Pelja, TB Wood's Inc., Chambersburg, Pennsylvania Andy Adams, Foseco Metallurgical Inc., Cleveland About the Authors Svetlana Dodik-Pelja is a foundry process engineer with TB Wood's Inc., Chambersburg, Pa. Andy Adams is a product application manager for ferrous filtration products with Foseco Metallurgical Inc., Cleveland.
Table 1. Scrap from All Causes With and Without Direct Pouring
Internal Scrap External Scrap Total Scrap
Before direct pouring 7.5% 6.0% 13.5%
After direct pouring 3.5% 1.5% 5.0%
Table 2. Metalcasting Facility Trail Cost Savings Analysis
Original Filtered
Runner System Direct Pouring
Metal Costs
Weight of casting
($0.10/lb. in mold) 25 lbs. 25 lbs.
Weight of runners
($0.05/lb. of returns) 6.6 lbs. 2.78 lbs.
Weight of feeders
($0.05/lb. of returns) 16.9 lbs. 1.47 lbs.
Total pour weight 48.5 lbs. x 2 = 29.25 x 4 =
97 lbs. 117 lbs.
Yield 51.55% 85.47%
Total metal costs $3.68 $2.71
Mold Costs
Sand-to-metal ratio 24.74:1 20.34:1
Cost of sand ($0.005/lb.) $1.25 $0.62
Cost of molding ($4.50/mold) $2.25 $1.13
Total mold costs $3.50 $1.75
Cost Summary
Cost of metal $3.68 $2.71
Cost of mold $3.5 $1.75
Cost of feeding systems 0.08 ($0.16/part) 0.50 ($2/unit)
Subtotal $7.26 $4.96
Scrap rate 13.5% 5%
Total cost per lb.
of cast metal $0.336 $0.209
Total cost $8.39 $5.22
Difference
Metal Costs
Weight of casting
($0.10/lb. in mold) (Same)
Weight of runners
($0.05/lb. of returns) 3.82 lbs. less
Weight of feeders
($0.05/lb. of returns) 15.43 lb. less
Total pour weight 20 lbs. more
Yield 33.92%
improvement
Total metal costs $0.97 less
Mold Costs
Sand-to-metal ratio 4.40:1 reduction
Cost of sand ($0.005/lb.) $0.63 less
Cost of molding ($4.50/mold) $1.12 less
Total mold costs $1.75 less
Cost Summary
Cost of metal $0.97 less
Cost of mold $1.75 less
Cost of feeding systems 0.42 more
Subtotal $2.30 less
Scrap rate 8.5% reduction
Total cost per lb.
of cast metal $0.127 savings
Total cost $3.17 savings
Table 3. Yield Improvement Summary on
Castings Re-Configured for Direct Pouring
Old New
Casting Configuration Old Yield Configuration New Yield
Gearing 4-on 47% 6-on 68%
Hub 1 2-on 44% 4-on 80%
Valve 1 2-on 48% 4-on 82%
Valve 2 2-on 47% 4-on 83%
Valve 3 2-on 47% 4-on 79%
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