Reciprocating power grinder reduces finishing time at Kovatch Castings. (Product Innovations).

Kovatch Castings, Inc., a 130-employee firm in Uniontown, Ohio, is a producer of ferrous and nonferrous investment castings from more than 150 alloys, ranging in weight from two ounces to 15 lb. It primarily serves the aerospace and military markets from its 40,000-sq-ft facility.

Similar to many foundries, Kovatch used hand labor to grind the gates of its investment castings using an old automatic grinder. The problem was that the firms productivity in cleaning and finishing was far behind and it needed to reduce set-up time for each job. According to Plant Manager Larry Moore, "The fixture costs were quite expensive, and the changeovers took too long."

To improve productivity, Kovatch recently added a Model PG-30 Reciprocating Power Grind programmable belt grinder by Grinding & Polishing Machinery Corp., Indianapolis. The 30 horsepower machine includes a twoaxis reciprocating table that makes it possible to grind contours as well as flat surfaces. Table motions include 12-in. vertical infeed and 30-in, reciprocating (horizontal) movement. Another feature is abrasive belt oscillation via a third wheel added between the contact wheel and drive pulley.

Both of the grinder's axes are servo-driven and dosed-loop controlled, and its memory includes data storage for 400 different parts. A radiused contour can be programmed by touching a finished part with the contact wheel at three X-Y points.

According to Moore, "Most of the grinding we have done so far has been with a simple mill vise. Even then, we're seeing productivity increases of 30 to 40%." Moore expects considerably more improvement with the expected addition of a hydraulically operated vise, as well as special fixtures for longer production runs. Compared to hand grinding, he adds, productivity increases of five to 10 times are common.

According to Moore, production quantities can run from 10 pieces to 3000 pieces. In addition, said Moore, "A lot of our parts are curved with a gate on the curve. With the new grinder, we can program it for either a convex or concave surface, as well as for a flat grind."

The new grinder is horizontal and grinds on top of the part, whereas the previous vertical grinder ground on the front. This requires a different type of fixturing but allows the use of the vise for small quantity production.

Tolerances are excellent with the new grinder and enable Kovatch to leave the exact amount of gate specified by the customer for finish machining. Moore states that some customers want 0.010-0.030-in. of gate left, while others want the area flush ground.

Typical alloys ground by the new system include carbon steel, 300-series stainless steel and tool steel, as well as nickel-and cobalt-base alloys.

Select No. 151 at www.moderncasting.com/info