BUMAX supplies MMG with high strength fasteners for energy saving ship propellers

BUMAX for Mecklenburger © BUMAX

Swedish specialist fastener manufacturer BUMAX has supplied premium stainless steel fasteners for German propeller manufacturer Mecklenburger Metalguss (MMG) and the company's innovative energy saving propeller cap, escap.

BUMAX models BUMAX 88 and BUMAX 109 in various dimensions have been purchased by MMG for their high tensile strength and corrosion resistance properties. This makes them perfectly suitable to fasten the MMG escap, a propeller cap with fins that can reduce fuel consumption by up to 3% by smoothing out the propeller swirl. The escap can be mounted onto existing propellers and the fuel savings typically provide a return on investment within three months.

MMG is a German leading manufacturer of next generation ship propellers and propulsion systems all around the world. The company uses precision manufacturing techniques and the highest quality materials and parts.

"Sustainability is key"

"Sustainability is essential for everything we do since our premium stainless steel products prolongs the life of all devices and constructions they are used for, and thus reduces the need for wasteful repairs and replacements," said Lars Holm, Managing Director, BUMAX. "In this particular case, fuel savings also equate to reduced environmental impact."

"Just looking at corrosion, the global cost of rust exceeds US$2.5 trillion annually, or three percent of global GDP, and the environmental consequences are enormous. Stainless steel fasteners offer significant benefits to counter corrosion, from product and asset infrastructure maintenance to total lifecycle costs." (Read more on this subject here)

MMG annually produces around 100 propellers at its foundry in Waren, northeast Germany. MMG propellers are used for various large container vessels, tanker, bulker and cruise ships and can be up to 12 meters in diameter.

"We have had very good cooperation with BUMAX as they have supported us with the design process and are always quick to respond to our queries," said Jörn Klüss, Head of Design and Construction at MMG.

High tensile strength bolting solution

MMG uses BUMAX for its escap solution since it needs high tensile strength bolts for safely transmitting the torque in existing propeller applications. Using standard stainless steel bolts would require expensive re-machining additional and/or larger holes in a dry dock to deal with the required torque. With BUMAX, MMG can install the escap while ships are in the water with diver installation teams as no addition holes are needed with high strength BUMAX bolts."

In addition, the good corrosion resistance properties of BUMAX 88 and BUMAX 109 bolts are essential as the fin caps are permanently submerged in seawater. The fin caps also play an important role in covering and protecting the shafting parts that are typically made of carbon steel and are susceptible to corrosion.The escap is fastened by up to 24 bolts depending on the cap size and uses bolt dimensions up to M36.

Larger dimensions for larger ships

"A number of container vessels and bulk carriers are already in operation around the world with an escap secured by BUMAX bolts," says Klüss. "The BUMAX bolts have performed very well and avoided the need for ship owners to undergo costly dry dock re-machining."

"We are currently working together with BUMAX to use larger dimensions of bolts to fit larger ships with escaps," concludes Klüss. "We have a number of projects in the pipeline that promise to realize more fuel savings for shipping companies around the world."