4+2 Machining Cuts Cycle Times From Days to Minutes

Machining bores with 0.0005-inch tolerances in 63-inch-diameter parts demands a rigid machine setup. For years, Highland Manufacturing achieved this through multiple setups on jig bores equipped with tilt tables. But setting up these jobs and running them was a time-consuming affair, often taking several days for complex jobs. As the jig bores aged and required increasing effort to meet the necessary tolerances, Highland and its president, Christian Queen, began looking for new machines that could simplify the process. It would soon cut its cycle times from days to under an hour with Soraluce’s TAD25 six-axis milling and boring machine.

The Soraluce TAD25 is the smallest of the company’s boring/milling machines, but its travels were still enough to match Highland’s jig boring capabilities. The machine’s full enclosure also helps keep the shop environment clean of chips and mist. Images courtesy of The Robert E Morris Company.

Meeting the Challenge

Highland Manufacturing is a Manchester, Connecticut-based 32,000-square-foot job shop working on prototype parts and tooling for the aerospace, defense and commercial space industries. Queen, the shop’s second-generation president, says Highland is best known for holding tight tolerances on large-scale tooling across materials from aluminum to alloy steels to plastics to nickel alloys. While large parts are the shop’s specialty, its work encompasses tools of many diameters and sizes. For these tools, it bores circular interpolated holes from a half-inch diameter and up.

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For much of the shop’s life, it relied on jig borers with travels up to 60 inches by 36 inches by 70 inches. The open construction of these machines enabled Highland to tackle parts larger than the machines’ tables, with the edges of the parts hanging out the end of the machine. But completing these parts often took days of setup and machining, and as the jig bores aged, they had a harder time meeting the shop’s ±0.0005-inch tolerances. When the shop looked at options for refurbishing its machines, costs proved high enough to convince Queen it was time to consider a new machine. Although the shop initially searched for a boring mill, most that it found did not match the shop’s travel needs. Eventually, the shop got in contact with The Robert E Morris Company, a distributor that pitched a six-axis Soraluce TAD25 mill.

The TAD25 is a six-axis machining center with a universal head and a built-in rotary table — Queen says it works like a boring mill and a jig bore in one machine. The machine’s 98-inch by 47-inch by 59-inch travels are the smallest of Soraluce’s lineup, but are large enough to meet Highland’s needs without overcrowding its shop floor. The shop considered the machine and decided to purchase it in early 2022.

The double-knuckle universal head on the TAD25 enables Highland to bore holes on any side of a part. While Queen says the shop does not perform simultaneous five-axis work with the machine, the machine has vastly simplified machining compound-angle holes.

Fast Results

From the outset, the TAD25’s double-knuckle universal head appealed to Highland. The head can index in two planes to an accuracy of 0.001 degree, enabling the machine to perform tricky work on compound-angle holes, complex contours and the undersides of parts. Queen says this massively cuts setup times and cycle times by itself, as the machine can complete jobs in one operation that would have previously required multiple setups, tilt tables or multiple machines. The six-axis access has also proved very useful for large aerospace tooling, as it helps the shop meet tight positional relationships between bores and features on different planes.

The machine also provides additional stability compared to the older jig bores, enabling the shop to perform light cuts like finish profiling and heavy machining like hogging on the same machine with only a change of cutting tool. Highland also makes use of Soraluce’s dynamic active stabilization technology, which has enabled the machine to hit true position and profiles with tolerances near 0.001-inch with the ram fully extended.

These features have made significant improvements to Highland’s ability to machine parts. Queen points to a job that had two-inch-diameter clearance holes going through a four-inch wall of plate as one example. On the jig bore, this job required five hours of setup, with a two-day runtime. Even then, the leadscrews on the X-, Y- and Z-axes (as well as the leadscrews for the horizontal rotary table) were prone to overtravel, complicating production of smooth, round features. While Queen says programming time on the Soraluce machine is the same, setup now only takes one hour, the cycle time is 45 minutes instead of multiple days and concentricity is much improved.

Highland’s Soraluce machine has also opened up new ways to machine complex parts. For one part with a 0.118-inch-wide groove, a +0.0005 and -0.0000-inch tolerance on the groove’s snap diameter, an interrupted cut and windows, the shop had difficulty producing it on a vertical turning lathe without snapping tools, and a partner grinding shop didn’t have a wheel small enough to make the groove. Eventually, the shop put it on the center of the Soraluce machine’s rotary table and attempted to make the groove with a seven-fluted endmill. By creeping up on size, the shop was able to machine the part with concentricity within 0.00015 inch.

The TAD25 uses Soraluce’s dynamic active stabilization technology, which minimizes vibrations and chatter when the machine ram is extended.

Careful Control

Because most of Highland Manufacturing’s jobs are for order sizes of one or two parts, Queen says the shop is extremely cautious to ensure success. But where caution may have required slower machining parameters in the past, now the shop relies on simulation software. Highland uses the simulation software within its Soraluce machine’s Heidenhain 640D control, which Queen says is as powerful as the machine. He emphasizes its ability to simulate operations even where the spindle is inverted to machine the underside of the part. While clearance issues have been Queen’s greatest concern with these programs, after three years he says the simulation has prevented any crashes.

The shop has also found the machine’s large swing arm console improves usability. The touchscreen can swing from the front to the back through the enclosure, letting machinists get close to the action and stop the program quickly if necessary.

The control and swing arm for the TAD25 can move through the machine enclosure to operate on either side of the machine. This helps machinists keep an eye on difficult cuts and intervene if necessary.

Highland has also made use of the “Virtual C-axis” feature on the Soraluce machine, which was critical in machining the grooved part. The feature enables interpolation of two linear axes in coordination with the C-axis of the spindle to emulate turning operations, despite the machine being known as a milling and boring center.

These features have made significant impacts on Highland’s throughput and enabled it to be more competitive on jobs. Even with order quantities of one or two parts, the shop has seen a sales increase of 10% since adopting the Soraluce machine, just from the new work the shop can take on. “It’s not just replacing a jig bore,” in Queen’s words, “it’s brought us new work that hits the bottom line.”