Hydraulic cylinders play a critical role for motion control within a wide range of industrial applications, and are invaluable for tasks such as lifting, pushing and pulling of plant and machinery.
Although the basic principles behind the construction and operation of hydraulic cylinders are similar to those used many decades ago, as with other types of industrial equipment – things move on.
Standardising dimensions
The dimensions of parts used on today’s hydraulic cylinders have been largely standardised to allow more flexible and convenient interchangeability regardless of the supplier. Over recent years, the British Fluid Power Association (BFPA), the British Standards Institution (BSI) and the International Standards Organisation (ISO) have all helped establish a more level playing field for sizes and specifications relating to hydraulic cylinders.
Material advances
While the main metal parts of a hydraulic cylinder usually operate efficiently with very little maintenance over many years, some parts may need replacing more frequently – the seals, for example. Originally seals were made of leather, however materials used today include rubber, polyurethane, PTFE, fabric reinforced elastomers and plastics. For applications where a high level of wear resistance is required, thermoplastic seals could fit the bill.
Higher levels of corrosion resistance
Traditional materials used to plate piston rods in hydraulic cylinders include nitride, chrome, chrome over nickel or other multi-layer/multi-process rod plating technologies, however recent developments have focused on alternative coatings that offer considerably greater corrosion resistance in more demanding environments.
Lighter weight
Traditionally, high strength steels have been used for typical mobile and industrial applications, while more expensive lower density alloys were used where reduced weight was critical. However, carbon fibre composite materials offer new possibilities for the design of lightweight, high-strength components. Lighter-weight, composite, corrosion resistant cylinders can improve performance in a wide range of applications such as mobile concrete pumps, aerospace, industrial robotics, sub-sea drilling rigs, wind turbines and military applications.
RFID
A recent development supporting Industry 4.0 is that of RFID (radio frequency identification). RFID chips placed onto seals can facilitate more accurate identification and traceability.
About the author and BFPA
This is an extract from an article by Trevor Hornsby, Chairman of the BFPA Technical Committee 3 (TC3) Cylinders. For the full article please visit the news pages of the BFPA website www.bfpa.co.uk
