Better cast iron milling

Manufacturing Engineering, Jul 2000

QC system from Vale(nite (Troy, MI) is des fined to effectively mill gray, ductile, malleable, and compactedgraphite cast irons. It is said to combine the best concepts in milling cutter design, insert geometry, and two complementary coated-carbide grades: SM838 and SM318. The first was developed for maximum wear-resistance at high speed and the second to provide greater toughness on roughing applications.

The QC system has two face-milling cutter styles, both with a 0 lead for square shoulder and limited-clearance milling. The first style, VFQS 90SE, is a generalpurpose cutter that uses screw-held square inserts with eight cutting edges. Negative pocket geometry in the milling cutter body enhances rigidity and strength. Body styles range from a 3" (76mm) OD with five inserts to a 12" (305 mm) diameter cutter with 18 inserts. Lock screws applied with 65 lb-in (7 N*m) of torque hold the inserts in place.

The second version, VFQS 90SD has adjustable wedge-held inserts. A cam adjustment simplifies setup and helps ensure fine adjustment. The fine pitch design.means less frequent cutter indexes are needed. Cutters range in size from a 3" diameter unit with 12 inserts to a 12" diameter version with 48 inserts.

Both crown and top-form wiper insert designs are available for this version. The first has a negative insert geometry and eight cutting edges. It is used when the milling operation does not need to wipe a shoulder. The top-form wiper has a positive insert geometry with four cutting edges to permit wiping to a shoulder.

The SM838 carbide designed for this system has a titanium-aluminumnitride PVD coating with a hard, smooth, dense surface. It provides a balance of wear resistance, toughness, and thermal crack resistance, and is intended for speed, of 700-1200 sfm (213-366 m/min) and feed rates of 0.004-0.010 ipm (0.10-0.25 mm/min).

The SM318 grade uses a mulitlayer CVD coating technology with 62 alternating layers of titanium nitride and titanium carbonitride. This material resists microcrack propagation and gives more consistent tool life. It is intended for rough cutting, works well with nonrigid spindles and unstable fixturing, and operates at 600-1000 sfm (183-305 m/min) and feed rates of 0.004-0.010 ipm.

Circle 320.