SE254HPC, SE255HPC and SE256HPC carbide drills are said to reduce cast iron machining costs by offering higher machining speeds. According to the company, the key is a high positive rake angle that reduces cutting forces and a sculptured edge drill geometry that increases centering at the top of the hole, which improves overall hole quality. The drills also feature an advanced PVD coating with a high hot hardness, shielding the cutting edge from the heat generated at high speeds. According to the company, savings are possible through reduced cycle time, higher part throughput, increased tool life and reduced cost per hole.
For example, on a ductile cast iron application, the new drills made it possible to increase cutting speed from 245 sfm to 600 sfm and a feed rate from 0.0064 ipr to 0.0080 ipr, providing a 67 percent reduction in cycle time. The new drills increased tool life on a gray cast iron workpiece from 3,256 linear inches with a solid carbide drill to 9,623 linear inches, providing a 195 percent improvement and saving $3,008 per year, the company says. They saved $42,000 per year machining 100,000 psi ductile iron at 350 sfm and 0.012 ipr through tool life and tool change downtime improvements.
The drills have design enhancements to address the challenges of machining cast iron. They feature a 135-degree point with a 45-degree corner chamfer that reduces tool pressure upon hole exit and prevents breakout in gray cast iron. Their new double-margin design provides four-margin contact over the entire hole cross-section, raising margin contact from 25 percent to 46 percent. This is said to improve drill stability in applications with irregular exits, angled entrances, inclusions and interrupted cuts such as crossholes. The drills are offered in a new grade, KC7315, that features a multilayer advanced physical vapor deposition coating with high hot hardness and surface smoothness, enabling higher speeds in cast iron machining. The grade also features a 9.5 percent cobalt submicron substrate.
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