Monday 10th February 2014

Stainless steel offset shaft couplings

Shaft Couplings used within determined industries sometime calls for customised materials to be compliant with special regulations and requirements. Examples of this include packaging machines for the food and pharmaceutical industries well as coating machinery under vacuum conditions. In such industries, the choice of high grade steel is adapted to the respective customer requirements. Many industries require the use of Stainless steel and the Schmidt-Kupplung product portfolio can meet this challenge across the majority of its product range.

Schmidt Products = Precision, high displacement and compact designs

For example, within the food-processing industry it is common to see shaft couplings being utilised in many areas of the driven part of the machine. The working axial area available for installation can often be very minimal. There can also be the case where the driven shaft coupling comes into direct contact with the food substrate. Mechanically, the shaft coupling must deliver reliable precision torque transmission, high torsional stiffness, axial shaft displacement and ease of fitting, these are typical application demands.

In this scenario the Schmidt-Kupplung range can offer a stainless steel solution called the Semiflex Compact Plus Type C320 with split clamp hubs. By using a split clamp hub solution there is no need to axially shift any bordering components of the machine during installation.  Additionally, the specific hygiene requirements can be met by using a high grade 1.4301 stainless steel for its construction.The torsionally stiff coupling, with an outer diameter of 120 mm, has a nominal torque of 316 Nm (maximum torque 330 Nm) and a radial displacement capacity of 3 mm, according to torque and displacement requirements.

What makes the shaft coupling unique is the transmission of the rotary motion and torque takes place in the coupling through two pairs of parallel links arranged at 90° to each other. They connect the driving side and the power take-off with the centre disc. The lateral displacement compensation takes place through a swivelling movement of the needle bearing parallel link rods on the connecting bolts that are located in the internal discs.

Innovatively, synchronisation between driver and driven ends is therefore guaranteed despite the high displacement. Installation of the coupling, which is already designed to be very compact, is made easy with an overall length of only 88 mm.
To meet the stringent regulations for machines that come into contact with food fit for human consumption, the needle bearings are equipped with food-grade grease. In other cases food legislation compliant slide bearings can be used. Similar coupling solutions are also applicable to packaging machines for the pharmaceutical sector and bottling plants. To some extent it was these industries that pioneered the use of 1.4501 stainless steel. Likewise other Schmidt couplings or indeed coupling components such as coupling links are made out of 1.4541 and 1.4571 premium steel.