Angle head for atypical prototype

Antron Engineering and Machine Co. Inc. is a contract manufacturer that employs about 100 people and has a machine shop that includes 50 CNC machine tools. The Bellingham, Mass., company produces parts from “so tiny you almost can’t see them in your hand up to single pieces that are 24″ in diameter,” said Anthony Denietolis, president of Antron.

Lot sizes range from one to 100,000 pieces, Denietolis added, and Antron frequently designs prototypes and tooling and builds inspection and testing equipment for its customers. “Our prototypes usually go directly into production as designed,” he said. “We design them to fit our equipment.”

One prototype, however, required Antron to purchase tooling to efficiently and consistently machine features in a cylinder housing made of 7075 aluminum. The component is part of a pump unit that runs the hydraulics for the controls and engines in a plane. “If something happens with the pump, you lose the plane,” Denietolis said.

The job required Antron to produce 10 each of the left and right housings. Denietolis explained that the challenge was milling a slot in a small-diameter bore, and the slot had an interruption and a large depth-to-diameter ratio. The specified bore diameter was from 2.6505″ to 2.6510″ (67.3227mm to 67.3354mm), the bore depth was 10.000″ (254mm), and the slot width was 0.160″ (4.06mm). The first slot started 2.050″ (52.1mm) into the bore and was 1.750″ (44.45mm) long, the second slot was 5.150″ (130.81mm) and a 0.500″ (12.7mm) space separates the two slots.

Antron Engineering and Machine applied a Titespot angle head from Eltool to mill an interrupted slot in a small-diameter bore. Image courtesy Antron Engineering and Machine.

The customer used to have a machine shop and produced similar features with a planing-type technique, where a nonrotating cutter shaped like an ice cream scoop scraped the surface to remove metal. “It is old technology, not quite as accurate as you’d like and extremely slow,” Denietolis said. “You’re not going to get any type of conventional tool in there.”

Initially, Antron wasn’t aware of an alternative method and considered planing or building a motorized head that powered a gear-driven tool and fit into the machine tool spindle. Denietolis soon realized, though, this strategy would be cost-prohibitive and not function effectively.