The end covers, fuel nozzles, ,bearing housings and associated components at the heart of a gas turbine are some of the hardest parts of any kind to manufacture. Forged and cast from high strength alloys, it takes precision machining of their complex geometries to ensure fitness for purpose in one of the most challenging environments imaginable.

Following our acquisition of M-Tech in August 2022, Impro now has the expertise and resources needed to produce gas turbine nozzle assemblies. Here’s a look at the capabilities available.

The Materials Challenge

Temperatures inside a gas turbine can reach the melting point of steel. What’s more, combustion gasses create ideal conditions for oxidation, exacerbated by the high pressures. In short, this is not an environment where conventional ferrous alloys can survive.

This is why the core components of gas turbines are produced from superalloys. These resist oxidation better than steel, and retain more strength at high temperatures. Interestingly though, their melting point is, in general, slightly lower than that of steel.

The answer to the question of how they survive comes down to gas flow and cooling. These parts are engineered so gasses flowing over their surfaces and through integral cooling channels take away enough heat to keep the alloy below its melting point. The challenge for manufacturers like Impro is, how to produce these geometries?

Investment Casting Expertise

The investment casting process is capable of reproducing fine detail, thin walls and smooth surfaces. By incorporating cores into the wax pattern it’s possible to form small internal features like cavities and cooling channels.

Investment casting excels with superalloys. These require precise control over casting parameters but the ceramic shells formed around the wax patterns are more than capable of handling the high temperatures.

Precision Machining Capabilities

The precision and repeatability of investment casting, coupled with the absence of draft angles and parting lines, reduces the amount of machining needed to arrive at the required geometry. Grinding is often preferred to milling and turning, and for particularly intricate features electro-discharge machining (EDM) may be necessary.

Heat Treatment

Optimizing the properties of investment cast and precision machined superalloy components often requires heat treatment. This ensures constituent elements are uniformly distributed throughout the matrix and required levels of toughness and ductility are achieved.

NDT and Inspection

Should a gas turbine engine component fail in service, the results are almost always devastatingly destructive. High speeds and pressures can cause a cascading series of component failures that destroy the entire assembly in milliseconds.

Such failures are avoided by subjecting every component to careful inspection, often including X-ray analysis to look for internal cracks and other defects. Non-destructive testing is often included in the inspection regimen to further assure quality of the finished parts.

Impro Has the Complete Manufacturing Solution

With extensive resources and expertise, Impro has long been a leader in investment casting of superalloys as well as ferrous and nonferrous metals.

Impro also has extensive precision machining, heat treatment and inspection resources. These range from milling, turning and grinding to X-ray inspection. Collectively, our casting and machining capabilities, coupled with close attention to detail and finely-honed QA systems, mean we can produce complex, highly engineered components and assemblies in a wide range of alloys.

These capabilities took a step forward in 2022 with the acquisition of Foshan Ameriforge Manufacturing Technology Co., Ltd. (“M-Tech”). Now operating under the Impro Aerotek banner, this adds gas turbine expertise, plus EDM and NADCAP-certified welding to our already wide range of skills and services.

More Than Gas Turbine Components

The ability to produce parts for gas turbines, from casting, precision machining, welding, assembly to finished item inspection, shows the depth and breadth of Impro’s metal part manufacturing capabilities. It would be a mistake though to think these capabilities are only for aerospace-grade applications. The total manufacturing solutions Impro can offer gas turbine engine builders and repairers extends into many other sectors.

Industries as diverse as medical devices, hydraulics, machine tools and automotive all stand to benefit from this vertical integration and in-depth expertise. Contact us to learn more.