Accounting for in-process metal loss: when quoting new work or re-pricing jobs with existing tooling, it is important to take your in-process metal loss into account and apply surcharges accordingly.How many pounds of metal does your customer buy when you sell him or her a 100-lb. casting? The most obvious answer would be 100 lbs., as shown on the invoice. But. in reality, the metalcasting process consumes considerably more metal. Considering the current cost of scrap, all metalcasters must be aware of the impact of process losses. This is particularly important for high alloy steel facilities. For others with lower metal costs, it may be a lesser factor but still an area to be researched from a cost viewpoint. The customer should pay for all the metal consumed in producing castings. In-process metal loss (IML See Simputer. IML - Initial Microprogram Load ) is the metal lost in the metalcasting process that cannot be re-melted for use as part of the charge for a casting in another heat. In applying alloy surcharges, it is particularly important that there be an accurate IML weight attributed to each casting, as world demand for high alloy materials, particularly in the developing nations, is projected to keep metal costs at their elevated levels for the foreseeable future. So, how much is that extra weight? According to according to prep. 1. As stated or indicated by; on the authority of: according to historians. 2. In keeping with: according to instructions. 3. recent studies, IML runs from 13% to 200%, depending on a number of factors. The basic equation says that the sold weight equals the finished casting weight a weight that turns a balance when exactly poised. - B. Trumbull. See also: Casting plus the IML weight. go find IML, you must add the losses incurred in melting, cut-off cut-off Anesthesiology The point at which elongation of the carbon chain of the 1-alkanol family of anesthetics results in a precipitous drop in the anesthetic potential of these agents–eg, at > 12 carbons in length, there is little anesthetic activity, and grinding. Melting Away There are five ways in which metal is lost during the melt process. 1. Oxidation--This can be seen in the fumes fumes odorous gases and other volatile materials; inhalation of irritating fumes causes coughing and, if sufficiently severe, irreversible pulmonary edema. coming off the furnace. It is dependent on how readily an element in the heat combines with oxygen at high temperatures. For instance, it is not uncommon to lose about 7% of the chromium chromium (krō`mēəm) [Gr.,=color], metallic chemical element; symbol Cr; at. no. 24; at. wt. 51.996; m.p. about 1,857°C;; b.p. 2,672°C;; sp. gr. about 7.2 at 20°C;; valence +2, +3, +6. contained in an initial charge. Other elements in the heat can be very stable with little or no loss, such as nickel. 2. Slag Entrainment--Slag is a complex manganese-aluminum silicate silicate, chemical compound containing silicon, oxygen, and one or more metals, e.g., aluminum, barium, beryllium, calcium, iron, magnesium, manganese, potassium, sodium, or zirconium. Silicates may be considered chemically as salts of the various silicic acids. . It can contain oxides, carbonates and other nonmetallic non·me·tal·lic adj. 1. Not metallic. 2. Chemistry Of, relating to, or being a nonmetal. Adj. 1. compounds that float to the surface of the heat When the slag is barred or raked off the top of the furnace or ladle, good metal can be entrained in the slag. 3. Skulls and Heels--Certain alloys have a tendency to adhere to adhere to verb 1. follow, keep, maintain, respect, observe, be true, fulfil, obey, heed, keep to, abide by, be loyal, mind, be constant, be faithful 2. the refractory refractory Material that is not deformed or damaged by high temperatures, used to make crucibles, incinerators, insulation, and furnaces, particularly metallurgical furnaces. walls of the furnace or ladle. At times, this metal can be recovered for re-melt. Other times. It ends up as trace elements Trace elements A group of elements that are present in the human body in very small amounts but are nonetheless important to good health. They include chromium, copper, cobalt, iodine, iron, selenium, and zinc. Trace elements are also called micronutrients. in the next heat. This is particularly a problem for high alloy stainless and nickel-base materials. 4. Spills and Splatters. 5. Run-Outs and Overfills. Metalcasters must develop a percent metal loss for their in-house melting processes, The specific number will vary between facilities, depending on alloy and melting and pouring practices The middle of the range of possibilities for percent metal loss is 7-8%. The number can be higher or lower in any given metalcasting facility; therefore, a conservative 8% loss factor can be used as a starting point Noun 1. starting point - earliest limiting point terminus a quo commencement, get-go, offset, outset, showtime, starting time, beginning, start, kickoff, first - the time at which something is supposed to begin; "they got an early start"; "she knew from the . However, you also can use 9 or 10% to err on the side of caution. Over time, you will want to develop costing methods that will enable you to establish the melt loss factor for your specific heats and casting types. In many cases, more pounds of metal are lost in melting than any other process. Because the loss is applied against the pour weight rather than the casting weight, yield is a major variable in determining the metalcasting process loss. If it is assumed that the melt loss is 8%, a yield of 50% means a total loss of 16% when compared to the shipping weight of the casting. Lower yield means greater IML. At 33% yield, the total loss becomes 24% of the casting weight. This sizeable loss is one more reason to work on improving yield by optimizing rigging rigging, the wires, ropes, and chains employed to support and operate the masts, yards, booms, and sails of a vessel. Standing rigging is semipermanent, consisting mainly of mast supports, the fore-and-aft stays, and the stays running from the masthead to each side . To calculate pour weight, the casting is weighed with the rigging on after shakeout Shakeout A situation in which many investors exit their positions, often at a loss, because of uncertainty or recent bad news circulating around a particular security or industry. Notes: During the dotcom boom and bust, numerous shakeouts occurred. and blast. Most metalcasters carefully record the pour weight because it gives the melt department the information needed to plan heats and not run out of metal or short-pour. It also allows planners to determine the yield. Frequently, the yield is used in evaluating the melting cost for the casting. It is a common element in establishing the sale price. What is overlooked is the impact it has on IML and the actual amount of metal sold on each job. Cutting Away Metal also is lost when you cut off gates, riser heads, bases and padding Bits or characters that fill up unused portions of a data structure, such as a field, packet or frame. Typically, padding is done at the end of the structure to fill it up with data, with the padding usually consisting of 1 bits, blank characters or null characters. See null and bit stuffing. . The percentage of loss is influenced by the complexity of the rigging and is usually the second largest, The IML for cut-off varies greatly from job to job, depending significantly on the method of cut off. * Arc-Air--The most common method of cut-off used in high alloy metalcasting facilities is arc-air. The metal at the riser contact area is melted with an electric carbon arc and blown off with a compressed air compressed air, air whose volume has been decreased by the application of pressure. Air is compressed by various devices, including the simple hand pump and the reciprocating, rotary, centrifugal, and axial-flow compressors. nozzle An orifice in an inkjet print head through which ink is sprayed onto the paper. Print heads with six thousand or more nozzles are common in today's printers. Nozzle integral to the rod holder. The resulting splatter is contaminated contaminated, v 1. made radioactive by the addition of small quantities of radioactive material. 2. made contaminated by adding infective or radiographic materials. 3. an infective surface or object. with carbon and to some degree copper and slag. Splatter cannot be used as re melt without extra refining. It is usually sold as scrap to dealers with access to argon argon (är`gŏn) [Gr.,=inert], gaseous chemical element; symbol Ar; at. no. 18; at. wt. 39.948; m.p. −189.2°C;; b.p. −185.7°C;; density 1.784 grams per liter at STP; valence 0. oxygen decarbonization de·car·bon·ize tr.v. de·car·bon·ized, de·car·bon·iz·ing, de·car·bon·iz·es To remove carbon from; decarburize. de·car refining and toll melting. However, arc-air is fast and it can cut along contours Contours may mean:
* Saw Cuts--Straight cuts that can be made with a 24-in. swing-flame Diction saw consume less metal than arc-air. The trade off is the difficulty of holding the part in a fixture for cut-off and the relatively high cost of the abrasion abrasion /abra·sion/ (ah-bra´zhun) 1. a rubbing or scraping off through unusual or abnormal action; see also planing. 2. a rubbed or scraped area on skin or mucous membrane. wheels. Smaller castings can be cut off with band saws when they can be held against the table surface. * Torch Cut-Off--Gas cut-off methods have restricted use in a high alloy metalcasting facility. However. losses are still prevalent with these methods. Individual metalcasters using torch cut-off can develop data for calculating IML. When determining cut-off losses, the operator should be careful to retain all the rigging that goes into the returns barrel. These re-melt items include riser heads and bases, sprues, padding, and runners and in-gates. It is a good idea to have supervision on hand to be sure all of the returns are carefully collected and weighed. The rough, un-ground casting also is weighed at this time. The difference between the pour weight and the rough casting weight plus returns equals the cut-off losses. On jobs where there are a lot of risers with large necks, numerous in-gates, heavy padding and risers mounted on curved contours, the losses can be huge. A typical example would be a pump casing. Grinding Away Losses in the grinding and finishing processes also must be taken into account. The amount of metal lost is dependent to some extent on how close the cut-off comes to the finished shape. This process usually has the least impact on the IML. If the castings are sold in the rough machined or finished part condition, the metal removed by machining also must be taken into account. After grinding, touch-up welding welding, process for joining separate pieces of metal in a continuous metallic bond. Cold-pressure welding is accomplished by the application of high pressure at room temperature; forge welding (forging) is done by means of hammering, with the addition of heat. , heat treat and blast, the finished casting is weighed prior to shipment. The difference between the rough casting weight and the finished casting weight is the loss attributed to the finishing process. This amount can range from negligible to sizable. There are minimal losses in heat treat and blast cleaning blast cleaning: see sandblast. that do not require any specific reference. By weighing the finished casting after all processing, these losses are accounted for. Considering the Variables Although IML calculations can show a wide variation, some general observations and guidelines are useful in applying the concepts to costing. The most important factors are the complexity of the rigging scheme required by the casting design and the resulting yield. Casting weight also is a major item. * The lower the yield, the higher the IML. * The more complex the rigging, the higher the IML. * Larger riser necks and bases produce higher IML. * Contoured riser contacts result in higher IML. * Padding that has to be removed equals higher IML. * Over-finishing (i.e. doing more than the specification requires) results in higher IML. * Arc-air cut-off means higher IML than saw cut-off. * Smaller castings generally have higher IML. * Similar types of castings often fall into the same IML percentage range. * Higher alloy content can result in higher IML. The above items are not highlighted as a methodology to reduce IML. Most of these factors are a function of casting design, specifications and established metalcasting procedures necessary to supplying the best product. These items are intended as a check-list to be sure they are included in your analysis of IML as a costing tool. For More Information Visit www.metalprices.com to view current alloy costs on the London Metal Exchange London Metal Exchange (LME) A market for trading base metals, where traded options contracts are available against the underlying futures contract. . James F. Cooke, Ancast Inc., Sodus, Michigan RELATED ARTICLE: Plugging in the numbers. The following equations are used to find a metalcasting facility's in-process metal loss (IML) for three castings. Each shows the percentage of the casting's weight that is lost every time the component is made. In the equations, [W.sub.P] = pouring weight, [L.sub.M] = melt loss, [W.sub.RC] = rough casting weight, [W.sub.R] = returns weight, [W.sub.CO] = cut-off weight, [L.sub.CO] = cut-off loss, [W.sub.FC] = finished casting weight, [L.sub.F] = finishing loss, and [L.sub.IM] = in-process metal loss. [W.sub.P] x %[L.sub.M] = [L.sub.M] [W.sub.RC] + [W.sub.R] = [W.sub.CO] [W.sub.P] - [W.sub.CO] = [L.sub.CO] [W.sub.RC] - [W.sub.FC] = [L.sub.F] [L.sub.IM] = [L.sub.M] + [L.sub.CO] + [L.sub.F] Ancast Inc., Sodus, Mich. determined the percentage of metal lost in the following three castings--an impeller housing, feeder housing and stuffing box. (All weights are given in pounds.) 1) Impeller Housing (CF-8M) [L.sub.M] = 488 x 0.08 = 39 [W.sub.CO] = 240 + 212 = 452 [L.sub.CO] = 488 - 452 = 36 [L.sub.F] = 240 - 226 = 14 [L.sub.IM] = 39 + 36 + 14 = 89 39% = Percentage of casting weight lost = 100([L.sub.IM]/[W.sub.FC]) 2) Feeder Housing (CF-8) [L.sub.M] = 112 x 0.08 = 9 [W.sub.CO] = 48 + 51 = 99 [L.sub.CO] = 112 - 99 = 13 [L.sub.F] = 48 - 45 = 3 [L.sub.IM] = 9 + 13 + 3 = 25 55% = Percentage of casting weight lost = 100([L.sub.IM]/[W.sub.FC]) 3) Stuffing Box (CD4MCu) [L.sub.M] = 214 x 0.08 = 17 [W.sub.CO] = 113 + 87 = 200 [L.sub.CO] = 214 - 200 = 14 [L.sub.F] = 113 - 113 = 0 [L.sub.IM] = 17 + 14 + 0 = 31 27% = Percentage of casting weight lost = 100([L.sub.IM]/[W.sub.FC]) James Cooke is the retired president of Ancast Inc., Sodus, Mich. |
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