New Machine Creates Complex Parts

Montreal’s Alta Precision added a new deep-hole drilling machine with a drop-bed design, engineered specifically for the company’s parts. Photo courtesy of UNISIG.

Situation

When commercial aircraft landing gear manufacturer Alta Precision, Montreal, recently expanded its production facility to introduce a new landing gear product, it was seen by the company as an opportunity to invest in updated capabilities.

Alta was faced with sourcing equipment to handle the complexities of manufacturing landing gear struts for the aerospace industry. By nature, its components are highly stressed, complex, with thin walls, and made from metals such as 300M alloy steel. Many parts require a profiled, deep-hole to be drilled and machined down the center.

At 9 in. in diameter and more than 7 ft. deep, the hole only can be performed on a dedicated deep-hole drilling machine, not a conventional machining center. In addition to having the capability to machine these bores to strict tolerances, the company was seeking a system that provided ergonomic setup and operation, with the versatility and power to handle a variety of complex parts in different lengths, on the same machine.

The landing gear struts also had additional challenges, such as an asymmetrical feature that required a swing of 54 in. and also acted as an off-center weight on a workpiece that is counter-rotated during the drilling process. All of these challenges exist in a single type of component that is essential to Alta’s business.

“In our industry, this is what’s known as a sole source contract. We’re the only supplier that makes this, so we have to deliver,” explained Alta Precision President Guillermo Alonso, “Our customer has no backup, so we have no room to fail. Having an unreliable machine that can’t perform isn’t an option.”

Resolution

Alta decided on adding a UNISIG B700 deep-hole drilling machine to meet the specific demands of this application.

This deep-hole drilling machine uses counter-rotating part and tool to maximize accuracy for solid drilling of holes up to 8 in. in diameter, and counterbored holes up to 12 in. in diameter, powered by automatically shifting headstocks.

The tool headstock is rated at 124 HP, while the work headstock is 90 HP, allowing Alonso’s team to utilize the power needed to cut tough alloys. High-performance spindle drivers deliver this power while monitoring the spindle motor speed, to automatically adjust output characteristics, regulating speed control to extremely close tolerances, regardless of spindle loading.

This machine is capable of performing the BTA deep-hole drilling process, along with alternative methods such as counterboring and forming, which are used on Alta’s landing gear struts for hole profiling.

The machine feed thrust is generated by 4-in-dia. servo-driven ballscrews, preloaded for high rigidity and zero endplay, improving tool life, depth control, and surface finish across multiple processes, especially bottom forming, states the manufacturer.

The machine was developed for Alta with additional features to reach specific design and performance goals, most notably being the drop-bed design to accommodate the extreme swing of the strut workpieces. The drop is specifically engineered for the range of parts that Alta was anticipating, but does so without sacrificing machine ergonomics or having major foundation requirements.

Workpiece spindle orientation and lock function simplifies part loading and unloading by starting and ending cycles in the most convenient orientation to the operator. Spindle orientation is also in effect on the tool side, ensuring the tool exits the workpiece at cycle end without risk of impacting the finish surface.

“UNISIG had the flexibility to listen to my needs, to take the time to understand, and to work with the design requirements,” said Alonso. “They really sat down and were active in the conversation, and brought the confidence of the design to the table. The machine is working perfectly.”

The drop-bed machine allows operators to program part length through the CNC, which automatically positions the workpiece headstock relative to the pressure head. Operators can set up and run parts quickly and easily, no matter what variations come their way.

Alonso also said that the ease of operation is notable, and the entire machine is accessible for operators – setup, indicators, controls, everything they need to run the highest precision parts.

“Everything came together and our UNISIG machine is an integral part of the cell for this component. We have a reliable machine and a reliable process,” said Alonso.