Structure and Working Principle of Wiper Seal

一、Product Structure Classification

Single-lip Wiper Seal（WA/WD）

It features a single dust-scraping lip with simple structure, low friction resistance and good versatility. Suitable for normal indoor applications with light dust conditions, it focuses on basic dust prevention with high cost performance.

Double-lip Wiper Seal（WDI/DKBI）

It has an outer heavyduty scraping lip and an inner oil-retaining secondary lip. The outer lip scrapes off silt, dust and water stains; the inner lip preserves the lubricating oil film on the piston rod surface to prevent oil streaking, dust accumulation and scaling. It is suitable for severe outdoor working conditions with mud, water and heavy dust.

Metal-cased Wiper Seal（DW）

It is reinforced with an internal metal skeleton for rigid support. It resists deformation, impact and dislodgement, and is suitable for largebore cylinders, highvibration and heavyduty construction machinery.

二、Working Principle

The wiper seal provides dynamic protection through interference contact of its lip against the piston rod surface.：

• When the piston rod extends outward, the lip closely fitted to the rod surface forms a precise scraping edge, which thoroughly removes contaminants such as dust, silt, metal chips and mud adhering to the piston rod, and prevents impurities from entering the cylinder.

• When the piston rod retracts, the lip has flexible compliance. It will not scrape off the essential lubricating oil film of the cylinder, maintaining a stable oil film between the main seal and the piston rod to prevent dry friction, ring burning and surface scoring.
• The inner secondary lip of the doublelip design can retain a small amount of oil to reduce external oil stains, achieving both dust exclusion and a clean, neat appearance.

Core principle: The wiper seal does not withstand or contain pressure; it serves only for protection. It protects the main seal and prevents premature wear failure.