Precision Ground Propeller Shafts

Stainless steel long bars supplied by Bird Stainless are a core component for many different industries and applications. One product area where we have recently become established as a high performance, quality supplier is marine propeller shafting, with our ground bars being used on both leisure craft and commercial work-boats. In this blog we’ll look at the reasons why we have become a key supplier to marine propeller manufacturers worldwide.


What boat owners are ultimately looking for is minimal noise and vibrations, coupled with efficiency in fuel consumption and longevity of the craft and its parts. High performance shafts are key to this, given that they create the torque required to turn the propeller blades. Precision grinding and straightening of the shafts to high tolerances is therefore key and at Bird Stainless we both precision-grind and straighten stainless steel bars in-house. This gives us full ownership of the production process, and we can ultimately ensure the high quality of the finished bars.  We can precision grind diameters from 2mm right up to 240mm in lengths from 2.5m to 12m.  We can also supply to a tolerance of 0.0005” and a surface finish of Ra 35 or better, depending on diameter and grade. The machined and straightened shafts are supplied with 3.1 test certificates and where required, 3rd party inspections by outside agencies such as Lloyds; DNV.GL; ABS; BV; RINA etc.

Technical Know How

We have a very experienced metallurgist within our Sales team, who if needed can provide assistance with technical specifications and help determine which grade will best suit the application for which it is to be used.  He is available by phone or email to advise on the properties of the various grades and, if necessary, will revert to the original steel mill for further confirmation.

Extensive Range of Specialist Stainless Steel Grades

Bird Stainless are specialists in stainless steels – that’s what we do! We know the sector inside out and often find that a lot of large general metal stockists buy from us because we have the depth of stock required in the specialist grades.  For the marine sector (shafts, rams and cylinders) the high performance stainless alloys used most frequently are:

  • F51 Duplex (1.4462) – a higher strength stainless alloy known for toughness & resistance to corrosion and stress corrosion cracking, which helps to prevent shaft failure. Especially good for high speed / high power applications.
  • 316L (1.4404) –an austenitic stainless grade with good resistance to corrosion & wear, plus good formability.
  • 630 H1150D (1.4542) – a precipitation hardening stainless steel with properties including high strength & with a moderate level of corrosion resistance & a high fatigue resistance.
  • 431 (1.4057) – a martensitic stainless steel with moderate resistance to corrosion. It also has good strength, hardness & toughness, but poor weldability.
  • 1.4418 – seen as ‘the up and coming’ grade, 1.4418 provides excellent fatigue resistance, high tensile strength & toughness even after welding. Good in slightly corrosive environments.

Speed of service and delivery

We understand how critical timing can be, both at the costing / quotation stage and also when sourcing components ‘just-in-time’ in a manufacturing programme.  We work hard to turn quotes around as soon as possible which, except for very complex requests, we usually do within the day, often within a couple of hours.  Having processing facilities and experienced, skilled staff on-site means we can turn around precision grinding, straightening and polishing processes swiftly as we don’t have to send bars out to an outsourced facility.


Bird Stainless has always been a family owned business, entirely independent of any larger stockholding company or steel mill.  As a result, we are in control of our own purchasing relationships and buy where quality is known to be excellent and where prices are favourable. This ensures that we can remain competitive and provide you with cost saving solutions.

We have built up a reputation for quality, sheer range of specialist grades, know-how, speed of service and competitiveness and are very proud to have been supplying stainless steel shafts to propeller manufacturers worldwide for many years. To see a case study of one of these, please click the link below: