Tis method is particularly effective for higher volume work. CLEAN UP OPTIONS CONSIDERED
The Abrasive Wheel
For the size of castings produced at Eagle Alloy, the abrasive grinding wheel is the traditional cleaning implement. Te facility uses a 30-in. snag grinding wheel with a bar grind. With this tool, operators can use their body to create more pressure against the wheel (Fig. 2). Eagle Alloy also has used a swing frame grinder, as well as cup grinders using the abra- sive wheel methodologies.
Arc Smooth Depending on the size of the rod, as well as operator
The auto-band saw cutoff method has shown an ability to save Eagle Alloy money primarily because the operator can leave the operation and perform other duties.
sensitivity, Eagle Alloy cleaning room operators also use arc welding to smooth gate areas. Te method consumes more energy but can be equivalent to a snag grinder in some cases and maintains a high level of quality.
Belt Grind
sizes used at Eagle Alloy, the group deemed it unsafe and eliminated the operation.
Auto Band Saw
Eagle Alloy has experimented with a traditional band saw on several carbon steel parts. Te saw allows an operator to per- form different tasks while it is in operation. Also, the consum- able costs associated with the saw are significantly less than other traditional methods. Te downside is the product must be normalized before cutting in order to optimize the use of the consumables. Te shell molding
facility also has experi- mented with a feeder band saw, generally used to cut tubing in fabrica- tion shops. In this appli- cation, the part’s gating is cut off from one side, and if the cut is parallel, the saw automatically moves to the next cut on the other side of the gate.
Eagle Alloy also has had success with belt grinding gate con- tacts. Te facility currently uses a belt grinder that is safe and requires an acceptable amount of pressure (the grinder puts 400 psi against the belt). However, the method is compatible with only certain gate configurations. In Fig. 3, a three-on fixture that is compatible with the belt grinding method is shown.
TWO WHEEL TESTS
In order to determine how much it costs per part (and square inch) to remove gates and clean contact areas, Eagle Alloy first used a cold wheel test. Te wheels at the time of the experiment cost $19.87 (note: prices in this arti- cle represent an adjusted value and should be used for comparison purposes only) and offered 235 sq. in. of usable wheel, making them $0.08 per usable square inch.
Fig. 1. Eagle Alloy recently added a coolant system for cutting the gates from crack sensitive materials.
March 2011 MODERN CASTING | 35
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