Blisk machining on an EMAG PO 900 BF.

Regulatory legislation is getting stricter about aircraft CO2 emissions at the same time the market expects rapid sector growth. Therefore, aero engines must reduce fuel consumption while increasing thrust.

As aero engine temperatures increase, so does efficiency. Higher temperatures demand extremely hardwearing materials that perform better under stress.

But that is only half of the matter – many components are becoming more complex and must be machined with high precision to achieve the targets set more than a decade ago for 20% reductions in CO2 emissions and fuel consumption.

EMAG ECM machine for the multi-station machining of turbine disks.

How can one process these materials with speed, precision, and process integrity? EMAG experts believe precise electrochemical machining (PECM) technology could be an answer.

The solution

PECM, electrochemical machining (ECM) technology, narrows the gap through which the electrolyte solution flows and optimizes the flow using mechanical oscillation. PECM allows complex components to be produced in demanding materials, machining high-tensile alloys and similar materials with minimal tool wear. Surfaces have no burrs, and the process does not change material microstructure. In contrast, the temperatures generated by cutting processes can generate heat-affected zones that alter material microstructures, and tool life is short in machining high-tensile materials. The high feed rates required to make machining economical also make machining filigree geometries difficult.

Machining area of an EMAG PO 900 BF for the machining of blisks using PECM (Precise Electro-Chemical Machining) technology.

Selective material removal

The electrochemical process ensures soft removal of material. The workpiece acts as anode (positive) and the tool as cathode (negative). Electrolyte solution flows between the two, dissolving metal ions on the workpiece. The cathode and workpiece, with their active, current-conducting sectors, are matched to ensure material removal from the workpiece produces the desired component contour. Contours, channels, grooves, and cavities are generated without touching the component for precise material removal. Also, ECM tools have a high life expectancy, reducing production costs compared to cutting tools.

Aero engine manufacturers are using EMAG PECM to rapidly machine central components such as nickel alloy blisks, disks, and individual blades with great precision.

For machining blisks, EMAG specialists developed a PECM system with 11 machining stations that drill, contour, radius-machine, and polish workpieces. High-tensile Inconel material is machined at a feed rate of 5mm per minute, achieving tolerances between 0.1mm and 0.3mm.

Modular PECM machines can be tailored to suit individual component requirements.

IMTS 2018 Booth #339436