coexistence of lubrication and sealing

Advancing Low-Friction Sealing with Polymer Brushes

Pursuing higher performance with advanced surface treatment technology. The company’s core sealing products, including oil seals and O-rings, are expected to deliver both airtight performance that prevents leaks and low friction that improves energy efficiency in machinery. These two qualities are often in tension, but NOK continues to refine both through ongoing R&D focused on surface functionality, materials, and component design, centered at its Shonan R&D Center in Fujisawa, Kanagawa. In recent years, this work has expanded to include polymer brushes, a surface treatment technology gaining attention worldwide. Rather than focus solely on short-term gains, NOK is pursuing mid to long-term research to improve the performance of its sealing products.

The Foundation of Oil Seals: Dual Mechanisms for Lubrication and Sealing

Oil seals are designed to prevent leakage of oils, liquids and gases while also providing lubrication that ensures the smooth motion of components like rotating shafts and pistons, as well as low friction. Oil seals used in automobile engines and motors are also built to last for 10 years or 100,000 kilometers without replacement. But how do they maintain seal integrity, preventing the leakage of oil and ther fluids through the gap between roating or reciprocating components and the seal, while also sustaining low friction over time? It might seem almost too convenient, but the secret lies in the coexistence of two mechanisms: lubrication, which enables low friction, and sealing, which prevents leakage. This article will explain these mechanisms in detail.

Handling Opposing Functions: Oil Seals and Surface Design

A major independent automotive parts manufacturer highly regarded for its technical capabilities. NOK is a key supplier to all Japanese automakers. Its particular strength lies in oil seals, the product the company was founded to manufacture. Used in engines, gearboxes and hydraulic equipment, oil seals must prevent the leakage of oil, water and gases while simultaneously circulating fluids on the sealing surface to enable lubrication. This low level of friction saves energy. Although they may appear to be simple rubber rings, NOK is constantly upgrading these oil seals through improvements in surface functionality, material selection and structural enhancement when in contact with rotating shafts.

Evolving Beyond Engine Applications: Oil Seals and Shape Design Technology

Oil seals — one of NOK's core products — vary significantly in shape, materials and structure depending on what is being sealed, the size of the shaft they are mounted on, and the type of movement involved. NOK produces around 60,000 types of oil seals, most of which are specifically designed for particular applications. While oil seals are widely used in automobiles, those used for engines and those installed in drivetrain components require entirely different properties. Despite all being referred to as "oil seals," they are fundamentally distinct products. For example, oil seals used in hub bearings near the wheels have undergone their own unique evolution.