What Is the


Gate Removal and Cleaning?


True Costof


Eagle Alloy recently challenged the traditional notions of evaluating cleaning costs to determine the best way to remove gating systems in its steel casting plant.


JOHN WORKMAN, EAGLE GROUP, MUSKEGON, MICHIGAN


However, engineers at Eagle Alloy, a steel shell molding facil- ity, recently decided to determine the benefit of reducing the size of the gate area, challenging traditional methods. Eagle Alloy is part of the Eagle Group of companies,


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which includes Eagle Alloy, Eagle Precision Cast Parts (an investment casting facility primarily pouring steel) and Eagle Aluminum Cast Products (a permanent mold and green sand aluminum plant). With experiments centered at the steel shell molding plant, the ultimate question was: what gating removal and cleaning method yields the best routing value (with value being defined as quality divided by price)? While the facility could not determine a standard cost per


square inch of gating material removed because of the differ- ent methodologies used and operator variability, it was able to rank each of its cutoff methods by economic effectiveness.


CUTOFF OPTIONS CONSIDERED


Oxy-Fuel Torch Eagle Alloy first considered the oxy-fuel torch cutoff method in its in-house experiment. Initially, the facility used this


34 | MODERN CASTING March 2011


hat does it cost to remove the gates from and clean a carbon steel casting? For years, the focus has been on yield versus gate size.


method with acetylene and oxygen for cutoff. It then began using MAPP gas, lowering costs considerably. About 20 years ago, a gas compressor was made available that would increase the pressure of the natural gas traditionally held in a plant from 3 psi to 12 psi so it could be used with a torch system. Eagle Alloy negotiated with the gas company and was able to install a separate natural gas line from the meter to the cutoff area at 12 psi, enabling torching with natural gas and again lowering costs.


Chop Saw


Eagle Alloy traditionally uses the chop saw gate cutoff method, when the gate configuration allows it. Te company uses a 20- or 22-in. abrasive cutoff saw and has experimented with many minerals, as well as a hot press vs. cold press wheel. Fig. 1 shows a coolant system that was added recently for cutting crack-sensitive materials. Te system has dramatically reduced cracking.


Friction Band Saw


Eagle Alloy used a friction band saw for many years, and the company’s investment casting facility, which produces primarily stainless steel castings, still uses it today. Te saw cuts stainless more easily than carbon steel, but with the gate


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