cylinder bed walking foot sewing machine

ERIKS type GV (type C according to DIN) is equivalent to type M, but is a heavy-duty version with a double metal casing. This can be a useful solution with larger diameters in more demanding applications. There is also a version of this type with a dust lip; the GVST (type CS according to DIN).

Oil seals are available in an immense range of sizes, for shafts from a few millimetres to several metres. Once the shaft diameter, groove diameter (housing diameter) and groove width are known, selecting an appropriate oil seal is a simple task. An oil seal or its product description is usually associated with three dimensions, for example 6x15x4. These refer to the sizes of the hardware for which the oil seal is designed. In this example, this oil seal is suitable for: 6-mm shaft diameter x 15-mm groove diameter x 4-mm minimum groove width.

PTFE Oil Seals - A relatively new and exciting oil seal, the use of polytetrafluoroethylene means that they can withstand dry or unlubricated operations. With a massive thermal range of  -130ºC to +200ºC and a strong resistance to chemicals, they are considered to be the future of rotary shaft seals.

In recent research, MWCNTs and carbon black were mixed with the butadiene/natural rubber to form a hybrid composite which gives very strong filler links by partial replacement of carbon black based on the m₁:m₂:X (m₁—MWCNT; m₂—reduction amount of carbon black; X-varies from 1 to 6) [40,64]. An internal blending mixer and two-roll milling were used to formulate the composites. The synergistic effect plays a major role in improving the abrasion resistance property due to the partial replacement of carbon black by adding MWCNTs in different ratios. The optimal ratio value of MWCNTs is 5 (parts per hundred of rubber) and 27.5 (parts per hundred of rubber) for carbon black with better resistant to abrasion compared to the matrix material [64]. The vulcanized hybrid composite material reinforced with MWCNT/carbon black at the ratio of 1:1 shows better mechanical properties, curing characteristics, and thermal conductivity. This shows a better tyre thread with an improved endurance life, less curing time, and improved thermal conductivity [42,64]. Fig. 4.4 shows the SEM and TEM images of uncured and cured rubber and Figs. 4.5 and 4.6 show the application of rubber nanocomposites in a tyre application.

• Super helix seal (seal with one-way two-step screw)

Nitrile Butadiene Rubber (NBR, nitrile)

Both sealing types are popularly used in different mechanical engineering applications. How are they different? The article explains the fundamental working mechanism of both categories of seals.

Leather is probably the oldest of the lip materials still in common use, but the move towards mass production methods has seen a massive increase in the development of synthetic rubbers which lend themselves to accurate and repeatable injection and compression moulding. Nitrile (NBR) is still by far the most common elastomer for “normal” use, whilst Viton® (FKM/FPM) is rapidly replacing Polyacrylate (ACM) and Silicone (VMQ) for high-temperature applications. Viton® also has high resistance to abrasion and chemical attack making it a preferred elastomer. Recent developments in the use of PTFE for Rotary shaft seals has caused widespread interest particularly for high-speed shaft rotation or poor lubrication applications.