Fig. 2. The abrasive wheel is one of several cleanup options employed by Eagle Alloy after the gates have been removed.
Te facility cut 1,604 sq. in. of the first part in the experi-
ment (part A) with 1,125 sq. in. of usable wheel: (1,125 * $0.08)/1,604 = $0.06/sq. in. = $0.24 per part (4 sq. in.) Industry standards indicate hot
wheels are more durable than cold wheels, so the facility next per- formed the test using a hot wheel at $36.25 for 235 sq. in. of usable wheel, or $0.15 per usable square inch. Eagle Alloy cut 2,055 sq. in. of part A, with 1,202 sq. in. used: (1,202 * $0.15)/2,055 = $0.9/sq. in. = $0.36/part (4 sq. in.)
Trough this calculation, Eagle
Alloy determined hot wheels at the given price were 33% more expen- sive than cold wheels.
OXY-FUEL TORCH TEST Eagle Alloy compared the cost
of consumables with the oxy-fuel torch using a #6 torch tip. Many variables come into play when using this method. In addition to cut costs, at-rest costs are introduced, as the gas remains constant in both states. Te oxygen, however, changes. At rest, oxygen flows at 55 cu. ft. per hour. While cutting, it flows at 350 cu. ft. per hour. At the time of the experiment,
the price of oxygen was $0.004 cu. ft., and gas was $0.00347 cu. ft. Following is a calculation of the cut cost for 100 pieces per hour with 20% cut time and 80% rest time: Cut gas: O² = 350 CFH at $0.004/ cu. ft.
CH4 = 20 CFH at $0.00347/cu. ft. At rest gas: O² = 55 CFH CH4 = 20 CFH
Cut: O² = 0.2 hour * 350 CFH * $0.004 = $0.28/100 CH4 = 0.2 hour * 20 CFH * $0.00347 = $0.014/100
Rest: O² = 0.8 hour * 55 CFH * $.004 = $0.176/100
ONLINE RESOURCE
Visit
www.moderncasting.com for an article on cleaning room automation.
36 | MODERN CASTING March 2011
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