Major Differences Between Lip Seals and CinchSeal Rotary Shaft Seals

Manufacturers Prefer CinchSeal Rotary Shaft Seals Over Lip Seals

Major Differences Between A Lip Seal And CinchSeal

It can be hard to understand what people are talking about when it comes to shaft seals. Not only are there quite of few kinds—O-rings, braided packing, mechanical face seals and so on—but it’s sometimes difficult to know which kind is under discussion. For example, lip seals have been called mechanical seals, which causes them to get confused with mechanical face seals. If you’re not an expert, it can get messy. But don’t worry, in this blog post, we will discuss two kinds of shaft seals — the lip seal and CinchSeal.

What’s the Difference Between a Rotary Shaft Lip Seal and CinchSeal?

Lip seals and CinchSeal have at least one thing in common. They serve the same purpose: preventing leakage and excluding contamination of the product being mixed or conveyed. However, there are major differences in the way these seals do their job and how well they do it.

Lip seals and Mechanical Packing

Rotary lip seals maintain a thin layer of lubricant between the “lip” and the shaft. The hydrodynamic action created by the turning shaft causes a pump action that helps hold the seal. The lip makes point contact with the shaft that forms two angles, and it is this contact with the rotating shaft that wears and damages the shaft. That is the major difference between a lip seal and CinchSeal.  

Lip Seal Advantages:

  • The biggest advantage of lip seals and mechanical packing used in stuffing boxes is their low cost, making replacements relatively inexpensive (but keep in mind that replacing these and product loss will take away from the initial savings).

Lip Seal Disadvantages:

  • Lip seals have a comparatively small surface they can grab the rotating shaft with. This design increases the risk of contamination and leakage in all applications of lip seals. Eventually, contamination creates a groove in a shaft and destroys bearings and gearboxes due to particle contamination.
  • The small surface area of the lip also makes lip seals wear out more quickly, especially in harsh operating environments. This requires lip seals to be replaced more frequently, eliminating much of their initial cost-saving benefit.
  • Lip seals have limited applications as their stationary design causes friction and heat generation. The viscosity of the sealed fluid will directly influence the friction generated in the lubrication film. For low viscosity fluids this can be a serious problem as the lubricant film becomes too thin to maintain the separation of the seal and the shaft.
  • Lip seals don’t withstand high pressure well, limiting their usefulness.
  • The non-rotating lip seal design can also cause shaft damage in a short period of time.
  • Finally, lip seals lack government certification necessary in meat, poultry and dairy processing industries. 
  • Mechanical packing is square braided rope packing that is compressed around the diameter of the shaft in a stuffing box. Packing wears with normal equipment operation and needs to be replaced often, which can be costly.
  • When abrasive bulk material is conveyed, it migrates into the seal area and becomes impregnated into the rope packing. The abrasive material starts to wear down the outside diameter of the shaft. The smaller shaft diameter reduces the strength and torque rating of the shaft and makes the sealing surface uneven and difficult to seal.

CinchSeal’s Rotary Shaft Seals

CinchSeal, on the other hand, represents a relatively new innovation designed mainly for mixersscrew conveyorsribbon blenders, and all kinds of bulk-handling equipment. The rotary shaft seals provide a high ROI, protect bearings and gearboxes, eliminate shaft wear and product leakage. Compared to lip seals and packing, CinchSeals eliminate unscheduled maintenance and downtime.

The self-adjusting design is made possible because the elastomer sealing element provides constant pressure against the sealing surfaces. Most shaft seals require periodic adjustment to prevent leakage. The CinchSeal is repairable and designed to disassemble so the sealing element can be replaced. Its replacement is much more cost effective than replacing the complete seal unit. Since the CinchSeal is self-adjusting, little or “near zero” maintenance is required.

CinchSeal Advantages:

 The CinchSeal has advantages over lip seals and mechanical packing in virtually every rotary seal application:

  • The CinchSeal unique rotating design eliminates the risk of shaft damage, inherent with lip seals and mechanical packing.
  • CinchSeal can tolerate shaft misalignment of up to ¼ inch, common in bulk-handling equipment, without losing its seal. This prevents leaks and material loss.
  • CinchSeal has a larger surface area than a lip seal, reducing the chance of contamination and leakage.
  • The seal’s self-lubricating design enables a dry-running seal operation, decreasing its wear and tear.
  • CinchSeal is USDA certified for meat and poultry, and dairy applications. In such hygiene-sensitive environments, it is vital to quickly disassemble and clean equipment on a daily basis.


Lower price does not translate to ROI value when it comes to deciding between rotary shaft lip seals and Cinchseal. Frequent repair and replacement of lip seals quickly eat into initial savings. It’s important to consider all costs related to your shaft seal choice when selecting the best solution for your application.

For over 25 years, CinchSeal has been a global leader in manufacturing innovative rotary shaft seals that serve as replacements for existing lip seals and mechanical packing, making machine replacements much less likely. We offer a variety of rotary shaft seals by size and design, so that you can find the right ones for you. If you would like a quote for our industrial seal solutions, contact us now. Quotes and drawings are guaranteed to be available in 24 hours, and custom engineering usually takes 10 days.

Share This Article

You Might Also Like

Site Search

Simply type in a search term to
find relative information on what you are looking for.

Schedule an In-Plant Assessment

Schedule an In-Plant Assessment

Request a Quote
Rotary Shaft Seals