What improvements can additive manufacturing bring in compressor manufacturing?

1. Breakthrough in design freedom: building complicated structures with engineering
The main problem that traditional compressor manufacturers face is the conflict between the need to improve aerodynamic performance and the difficulty of processing complicated structures. As an example, the adjustable diffuser of a centrifugal compressor needs to be able to bend at multiple angles in a span of a few millimetres. Traditional five-axis machining needs to clamp the workpiece several times, which causes surface defects to build up and makes it impossible to create the best flow channel since the tools get in the way.
The Institute of Engineering Thermophysics of the Chinese Academy of Sciences made a big step forward by using selective laser melting (SLM) technology and 1.2709 die steel to print an adjustable diffuser with 12 separate pressure channels all at once. The component reveals by surface error detection that the deviation of all inlet holes is regulated within 0.3mm, which is 40% greater than the usual process accuracy. Additive printing also lets the design team turn the best flow path curve in aerodynamic simulation into a solid structure. This makes the diffuser 8% more efficient and increases the operating flow range by 15%.
In the area of rotary screw compressors, this freedom to design is also clear. Meltio's robot-integrated cladding technology gets rid of the boring process of traditional forging machining by directly printing 316L stainless steel screws on the tops of bars that have been accurately calibrated. The screw part it printed is 75 × 75 × 230mm and has a surface roughness of Ra0.8 μm. The screw clearance is kept to within 0.05mm, which is three times more accurate than traditional methods, thanks to five-axis precision machining.
2. Big jump in manufacturing efficiency: from monthly cycles to weekly deliveries
The traditional way of making compressors has a lot of "time barriers." For example, making the adjustable diffuser for the core compressor of a 100MW compressed air energy storage system takes 12 steps, including forging procurement (2 weeks), rough machining (3 days), heat treatment (5 days), precision machining (1 week), assembly and commissioning (3 days), and a total cycle of 6–8 weeks. The "printing post-processing" method of additive manufacturing technology shortens the cycle time to less than 10 days.
The Institute of Engineering Thermophysics has real-world data that indicates SLM printing of diffuser substrates only takes 36 hours. With automation to help with hot isostatic pressing (HIP) and surface cleaning after printing, the whole delivery cycle is cut by 75%. This increase in efficiency is more useful in emergency maintenance situations. For example, a chemical company once had to shut down a production because a compressor impeller broke suddenly. Using additive manufacturing technology, it only took 72 hours to go from CAD design to replacing spare components, saving the economy tens of millions of dollars.
The economics of additive manufacturing is even stronger because it uses a lot more materials. In the past, making screw compressors meant that the weight of the forging blanks was frequently 3 to 5 times that of the finished products. However, Meltio's cladding method keeps material loss to less than 5%. If a compressor company makes 5,000 units a year, it can save about 200 tonnes of stainless steel materials per year, which lowers the cost of raw materials by 4 million yuan.
3. Expanding the Performance Boundary: Working together to create new materials and structures
Additive manufacturing not only affects how things are made, but it also encourages the development of new compressor material systems. When the pressure ratio and temperature difference are quite high, typical nickel-based alloys are getting close to their performance limits. The electron beam additive manufacturing technology created by the Oak Ridge National Laboratory in the US has successfully printed tungsten parts that are free of defects and have a high-temperature strength of 420MPa (1000 °C). This is 60% stronger than traditional nickel-based alloys and is a key material solution for supercritical carbon dioxide compressors.
The combination of topology optimisation and additive manufacturing has led to innovative designs in the field of structural innovation. A particular company has produced an aviation compressor turbine disc with a biomimetic lattice structure. This makes it 45% lighter while keeping its strength, which increases the engine's thrust-to-weight ratio by 12%. It is even more important that additive manufacturing has made functional integration design possible: A certain kind of compressor housing combines the cooling channel, the sensor mounting seat, and the structural body for printing. This cuts the number of pieces by 37% and the time it takes to put them together by 65%.
4. Lifecycle Management: A shift in thinking from making things to providing services
The service model for compressors is changing because of additive manufacturing. General Electric's "On Site Manufacturing" programme has sent out 200 mobile additive manufacturing machines across the world. These devices provide real-time manufacturing services for compressor spare parts in places like oil and gas platforms and mines that are hard to get to. This dispersed production methodology cuts the time it takes to get spare parts from weeks to less than 48 hours and lowers inventory expenses by 80%.
When it comes to maintenance, combining additive manufacturing and digital twin technologies makes it possible to do predictive maintenance. Siemens' compressor health management system can precisely anticipate how much longer parts will last. It does this by putting sensors in important parts to capture real-time data on stress, temperature, and other factors, and then combining that data with a database of additive manufacturing processes. When the wear on a given screw compressor rotor gets close to the limit, the system automatically makes an additive repair plan. This plan just needs to cover the worn area, which cuts the total cost of replacement by 90%.