Propeller Manufacturing: Bronze Casting to ABB Robots

A big ship propeller is cast in one piece, can weigh more than 30 tonnes and still has to match its design closely. Propeller manufacturing has always mixed foundry work with slow hand finishing, and that finishing is where robots are starting to help. This post follows the job from the first screw propellers of the 1830s and the brick moulds of early foundries to today's CNC milling, robot grinding and 3D printed propellers. It also looks at where ABB robots could fit, and at the cost, safety and skills problems that keep much of the work manual.

An MMG ship propeller displayed outside the SMM fair halls in Hamburg, 2010. Photo: Dr. Karl-Heinz Hochhaus / Wikimedia Commons (CC BY 3.0)

How screw propellers were cast and ground by hand

An inscription of the Assyrian king Sennacherib, who ruled from 704 to 681 BC, describes casting water screws in bronze. The ship propeller is far younger. Francis Pettit Smith demonstrated a wooden screw propeller on a six ton canal boat on the Paddington Canal from November 1836, and SS Archimedes, built in 1838 in London, was the first steamship driven by a screw. In 1845 the screw steamer HMS Rattler pulled the paddle steamer HMS Alecto backwards in a tug of war, and Brunel's SS Great Britain crossed the Atlantic under screw power the same year.

The propeller under the hull of the SS Great Britain in its dry dock in Bristol. Photo: Nortix08 / Wikimedia Commons (CC BY-SA 4.0)

Over the following decades large propellers moved from iron to bronze alloys, which stand up better to seawater. Making one was foundry craft. Moulders built the mould from brick and loam on a heavy base, shaped the blade surfaces by hand and left a cavity for the hub and blades, and the whole propeller was poured in one go. Getting the blade shape right depended on the moulders' skill and on templates, because any error in the casting had to be removed later with grinders and files.

Moulders preparing a brick and loam propeller mould for casting, from a World War I era US Army Signal Corps series. Photo: US National Archives via Wikimedia Commons (public domain)

The finishing that followed was dusty, noisy work. A US Army Signal Corps photo from December 1917 shows three men finishing a propeller with handheld pneumatic grinding wheels, wearing simple respirators against the bronze dust. Workers checked pitch and thickness with gauges and templates and kept grinding until the blades matched. Machine tools later took over much of the shaping, but the final surface on many propellers is still ground and polished by hand. Our post on grinding and deburring covers why that kind of finishing is so hard to automate.

Workers finishing a propeller with pneumatic grinding wheels, December 1917. Photo: US Army Signal Corps / US National Archives via Wikimedia Commons (public domain)

Propeller factories, robot grinding and the news in 2026

Today the large propellers for container ships and tankers are still cast in one piece from propeller bronze, then machined on large multi axis CNC milling machines and measured against the tolerance classes in ISO 484. One of the best known makers is Mecklenburger Metallguss (MMG) in Waren, Germany. Its propeller has become a landmark of the SMM maritime fair in Hamburg, and the one installed for SMM 2026, held from 1 to 4 September, weighs about 35.5 tonnes, measures 7.8 metres across and has five blades. MMG built it for the 4,300 TEU container ship KMTC Nhava Sheva, and it will go to sea after the show.

The Mecklenburger Metallguss propeller works in Waren, Germany, 2014. Photo: Wolkenkratzer / Wikimedia Commons (CC BY-SA 4.0)

Robots are taking on the finishing. Mirka offers a propeller finishing system built from one large payload robot with force control and a precise rotary table, aimed at fixed and controllable pitch propellers. Researchers have tested robotic belt grinding of whole blades; one study in the journal Robot reported deviations below 0.1 mm. Printing is the other trend. In 2017 the WAAMpeller, built by RAMLAB in Rotterdam from 298 layers of nickel aluminium bronze, became the first class approved 3D printed ship propeller, and on 1 October 2026 3D Printing Industry reported that Mencast Marine's wire arc printed propeller had earned dual class certification.

A finished MMG propeller on display in Waren, 2017, its blades ground and polished. Photo: Frank Liebig / Wikimedia Commons (CC BY-SA 3.0 de)

We found no published ABB project for propeller grinding, so the following is a possibility. A heavy arm such as the ABB IRB 6700 already grinds steel parts in cells like the Teqram EasyGrinder, and ABB builds Foundry Plus versions of its robots for dusty, wet cells. With force control, such a robot can keep steady pressure on a curved blade while a rotary table turns the propeller. ABB also has its own link to propellers through Azipod, its electric podded propulsion, and its robots already weld in shipyards, as our post on shipbuilding welding shows.

An ABB IRB 6700 grinding a steel part in Teqram's EasyGrinder cell at Ancofer. Photo: ABB

Where propeller manufacturing goes next

In factories, the likely next step is a closed loop: scan the casting, compare it with the CAD model, let the robot grind only where metal is left, then scan again. That would cut the long manual hours between casting and delivery and keep workers out of the bronze dust. Path planning is the hard part, because every casting differs slightly and the blade surfaces twist. Offline tools such as RobotStudio and its Machining PowerPac let engineers generate grinding paths from CAD and check reach before a robot touches a real blade.

A white ABB foundry robot works in steam at a Buhler die casting cell. Photo: ABB

For ships in service, propellers also need polishing and repair, usually in dry dock or by divers. Wire arc printing may change repairs first, since a damaged blade tip could be rebuilt layer by layer instead of recast. For smaller boats and yachts, the same printing and robot finishing methods could make one off or replacement propellers easier to get. Owners of small boats will probably still buy standard cast propellers, but larger and custom propellers are where the new methods are most likely to appear.

Workers on a lift beside the propeller of the ferry Stena Superfast VII in dry dock in Belfast, 2017. Photo: Rossographer / Wikimedia Commons (CC BY-SA 2.0)

Propellers are made in small batches, often one at a time, so a robot cell must handle many shapes and sizes without long reprogramming. The parts are heavy, which means large fixtures, cranes and safe zones around robots, where tools like SafeMove help. Skills may be the biggest gap. Experienced propeller grinders know by eye and feel when a blade is right, and that knowledge has to be turned into measurements and robot programs before it retires with them.

An ABB IRB 1300 with Foundry Plus 2 protection, built to handle water and dust. Photo: ABB

Innovation

AI solutions for effortless ABB robot control.

Automation

Robotics

ceojohntran@chatwithrobot.net

+84905311611

© 2025. All rights reserved.

qtran1215@gmail.com