Piston seals

Introduction

Seals are often the weakest and most sensitive machine element in components that make up various sorts of machinery. It is mostly the seals that set the limits, both of the components and the entire machine ́s length of life, their function their servicing requirements. The sealing function in general is characterized of the seals themselves making up a very small part of the total cost. However, with the seal ́s demand for dimensional accuracy and surface finish of the cylinder bore, it will force high costs that will take a big share of the total value of the finished product. As an addition, the functioning and the life for the total product and therefore the total economy is generally settled and limited by the seal. The total cost for tightness is thus not only a highly dominating cost, apart from material cost, but also the cost where you have greatest change to get a good economical improvement as a result of altered and improved sealing technique.

Metseal is a patented totally new seal technique for applications within hydraulics, pneumatics and control engineering and for piston machinery of varying kinds, e.g. in compressors, pumps, motor etc. The sealing system consists normally of a primary seal ring of metal with a hard and smooth contact surface and usually an O-ring, providing secondary sealing between the ring and the piston ́s sealing groove. In example within the area of hydraulics, the seal is made of quenched and tempered high-alloyed special steel. For pneumatic cylinders with the cylinder tubes in aluminum, the seal is also manufactured in aluminum but with a very hard surface. By choosing material with the same thermal expansion coefficient in the cylinder and in the sealing ring the influence of temperature can be minimized.