MARKETING MATTERS CAST TIP
Optimizing Cleaning Room Abrasives B
STEVE ROBISON, AFS SENIOR TECHNICAL DIRECTOR
onded abrasive products are important elements of a metalcasting facility’s clean-
ing room. Te traditional “grinding wheel” has become more advanced as manufacturing technologies and new materials have led to abrasive products that last longer and cut faster. As a result, foundry customers have the op- tion of using specialized products for nearly every casting application.
Abrasive Materials Te most commonly used
abrasive materials are silicon carbide, aluminum oxide, zir- conia, ceramics or a blend of the above. (Diamond abrasive bonded to steel wheels can be used as an alternative to these products, especially in high volume applications.) Te typical bonded abrasive can be made in different densities and grit sizes. Each metalcasting facility should work with its supplier to fit abrasives to the individual needs of each application. For gate and riser removal
ized for the cast material.
• Equipment: Is the equipment manual or automated? What are the speed, horse power and RPM of the grinding machine or tool? For optimum productivity, it’s important all equipment is properly maintained and oper- ated at maximum capability. Each abrasive component must be matched carefully to the speed of the equipment to ensure proper product safety. Additional consid-
Each metalcasting
facility should work with its supplier to fit abrasives to the individual needs of each application.
and grinding, there is no universal abrasive—that is, a single abrasive material cannot handle all grinding needs. Each metalcaster should ex- periment to find the best option for each application. The typical iron or steel facility may use several differ- ent abrasives, such as cup wheels, discs, cutting wheels, grinding wheels and mounted points, and may require a different abrasive material or hardness for each cleaning room stage. The choice of which abrasive to use depends on several factors: • Metal: The many grades of cast iron and various steel alloys all grind differently and might re- quire different grinding materials. Hardness and grit can be custom-
eration should include auxiliary equipment used in the grinding and cutting process, such as pres- sure assist, fixtures, etc.
• Operator: How much pressure will the operator apply? Is a hydraulic power assisting? Some ceramic abrasives thrive in high pressure ap- plications but might not be utilized fully in lower pressure operations.
• Gating and Riser Design: How much metal must be removed? Are the riser cuts close to the casting or does the casting geometry limit access and require larger riser pads to remain?
• Life Expectancy: How long do you want the abrasive to last and how fast do you want to grind or cut?
If the cut speed and reduced man hours are important, these consid- erations will affect the choice of abrasive. “Softer” wheels will grind faster but wear out more quickly. “Harder” wheels will grind more slowly but last longer.
• Cost: Calculate the total cost of use, not just the purchase price, when com- paring abrasive products. “Premium” products such as ceramics or diamonds may be more costly to purchase, but longer life and/or safer operation can offset the initial investment.
Safety Bonded abrasive cutting
wheels, grinding wheels and specialty products such as cup wheels, discs and points are abrasive grains, bonded together and reinforced to meet federal safety standards. Each product has a maxi- mum operating speed, and it is critical the wheel speed and equipment speed are matched. Placing a wheel on a piece of equipment that is turning faster than the wheel
was manufactured to go is danger- ous and can lead to wheel failure and worker injury. All equipment also must have
appropriate guarding and work tool stands. For best productivity and safety, training is critical for all clean- ing room personnel. All workers are recommended to go through both regular in-house training and profes- sional training, which often is pro- vided through the abrasive manufac- turer. In addition to all those working regularly in the grinding operation, those who are cross-trained and oc- casionally serve in this area should be included. Clear, written procedures on mounting the wheel and safe opera- tion are essential.
January 2014 MODERN CASTING | 55
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