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 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 ship propellers and propulsion systems all around the world. The company uses precision manufacturing techniques and the highest quality materials and parts.
“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.”
“Stainless steel fasteners offer significant benefits to counter corrosion, from product and asset infrastructure maintenance to total lifecycle costs.”
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.
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 additional 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.
Klüss adds: “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. We have a number of projects in the pipeline that promise to realize more fuel savings for shipping companies around the world.”
