Canadian Machinery and Metalworking Magazine
by Kim Laudrum, Editor
Issue: Volume 99, Number 5 - July 2004
For more than a century, Siemens Westinghouse has helped Canadians power their
homes and businesses. Recently, the company invested $4 million to machine gas-turbine
engine rotor components as large as 12 meters in length. Now, thatıs one powerhouse
lathe.
At the beginning of the 20th century, George Westinghouse accurately predicted
Hamilton, Ont. would be a good place to locate a company dedicated to manufacturing
products related to electrical power. Close access to both major train routes
and steel supply must have motivated his decision. As did the then-recently-installed
power generation plant at Niagara Falls, for which the Hamilton plant produced
water wheels. So, in 1903 the Canadian Westinghouse Company Limited was incorporated.
Soon, consumers all around the area would be demanding lamps for reading, and
other household electrical appliances; things made at the then-expanding Hamilton
plant, of course.
The company, along with the Canadian economy, boomed. In the 1950s, Westinghouseıs
turbine power generation business became a distinct division. By the late 1960s
the company focused primarily on power generation and household appliances, with
a research and development arm in electronics. By the end of the 1980s and into
the 1990s the company focused on gas and steam turbine manufacturing where markets
were picking up. In 1998, CBS, which had bought Westinghouse years earlier, sold
the Power Generation Unit, including Hamiltonıs Sandford Avenue and Beach Road
plants, to Siemens AG of Germany. Since then, the company has been known as Siemens
Westinghouse, Inc.
Itıs this history that intrigues me when I am invited to visit the plant to check
out the installation of what is probably the largest capacity turning centre of
its kind in Canada. What prompted this investment in a $4-million lathe?
D'Arcy Wilson, Manager, Manufacturing Technology, Facilities and Maintenance,
at Siemens Westinghouse (SW) explains that when the company looked at a reinvestment
strategy between 2000 and 2002, the electricity program at SW was at its height.
Most of the demand for their gas turbine rotors was in the United States. The
companyıs 501 F and 501 G the worldıs largest conventional gas turbinewere
selling well on a regular basis around the world.
Gas turbine engine
The beauty of the gas turbine engine, explains Plant Manager Allan Ingram, is
that you can bring it "up to speed quickly maybe within an hour. If you
combine them with steam turbine engines, to preheat water, for example, you can
get much higher efficiencies."
The 501 G turbine engine weighs 265 tons, and generates 235 megawatts of power,
"or 390,000 horse power in laymanıs terms," laughs Ingram, but he says
it can go even higher. "The inlet airflow is 1,200 lb/sec or 72,000 lb/min.
Itıs staggering."
The power generation engine plant reached its peak capacity making 61 of the 501
F engines in one year. "But that was before Enron," notes Ingram. The
market has since collapsed. Currently, the plant is working at a pace of about
11 engines per year.
"We were producing an engine a week and we needed a machine capable of doing
all these functions on the rotor," Ingram recalls. So the decision was made
to invest in a Safop lathe and two Tacchi machines, which are used primarily for
grinding. However, following the market collapse, the order for the second Tacchi
machine was postponed. One Tacchi has been installed at the plant as part of the
rotor cell.
The Safop model Leonard 80/400/CNC is a turning and milling machine with the capability
of machining shafts 3.2 m in dia. and 12 m in length, weighing as much as 110
tons, according to Ed Cahsens of Cahmac Machinery,
the Canadian distributor of Italian machine-tool builder Safop.
The size is important. Ingram points out that the combustion power engines, when
fully bladed, are very large and weigh 66 tons.
Unique production process
The production process is unique. "We have a different philosophy. We do
a total rotor stack," Ingram explains. A cell next to the lathe is where
the rotor blades are vertically stacked. "Itıs about 85 per cent complete
by the time we put it on the Safop lathe."
From the stacking cell, the rotor is moved by crane onto the Safopıs bed. And
because the rotor is so large, the machinery has to be. The Safop lathe is a "twin-bed
machine, fully hydrostatic. The left-hand side has a carriage, fully indexable
with milling and turning capability, Ingram explains. The other carriage has milling
capability only. Each carriage has a C-axis headstock that is fully controllable,
making this a seven-axis machine. The Safop also has a 3.3 m swing over the carriage
and a distance of 14 m between centres. It has a Siemens Sinumerik control, ("obviously,"
notes Ingram, this is Siemens Westinghouse, after all").
When the rotor disks are assembled and the rotor is placed on the Safop, two large
radial holes are drilled where the disks meet. After that, a radial pin is put
in place. Accuracy is important. Thatıs one of the reasons why the company selected
the Safop lathe; it can hold an accuracy on the total travel bed, which is 13.5
m long, within 14 µm.
Ingram notes that combustion power turbines have evolved over the years. "Theyıve
gotten bigger and must withstand higher temperatures," he said. Increasing
the efficiency of the turbines has meant putting together tighter tolerances on
the machine.
"There is not a lot of room for error," Ingram notes, "when tolerances
are about one-tenth of a thousandth." The materials used for the high-heat
tolerant parts of the compressor are not easy to machine either. Ingram says they
machine mostly 4140, or stainless, but they also use a lot of Inconel. He says
they have found ceramic cutting tools good for milling, especially materials at
62 or 63 RC. "The Inconel is more sticky than hard so you canıt run with
high speed machining."
The Safop also comes with a teleservice back-up from Italy. "Thatıs worked
a treat," Ingram says.
Although the lathe was not yet in production when I visited, Ingram was optimistic.
"The work so far has been meticulous and the geometry is the best of the
lathes weıve seen."
