How are seal rings made?

The manufacturing process of seal rings is like a combination of making gummy candy and metalworking. The process varies depending on the material. Here are the steps:

I. Rubber Seal Rings (O-rings, Oil Seals) Manufacturing

1. Material Preparation: Preparing the "Rubber Dough"

Chop raw rubber blocks (such as nitrile rubber or fluororubber), add pigments, antioxidants, and other additives, and mix well like kneading dough.
Key Point: The formula is a secret! The performance differences between manufacturers lie in this "secret ingredient."

2. Molding: Pressing Out "Rubber Strips"

The mixed rubber compound is fed into an extruder (like a giant noodle machine), producing continuous rubber strips (thickness = seal ring cross-sectional diameter).
Example: Making O-rings is like squeezing toothpaste, but you're squeezing out hot rubber strips.

3. Shaping: Cutting and Vulcanizing

Cut the rubber strips into sections according to size, and cut beveled ends at the joints (Figure 1). Press the rubber into a mold and bake at high temperature (150℃~200℃) – this step, commonly known as "vulcanization," is crucial for the rubber to become elastic.
Note: The shape of the mold cavity determines whether the final product is an O-ring, oil seal, or a custom-shaped seal.

II. Manufacturing of Plastic Sealing Rings (e.g., PTFE)

1. Blank Formation: Pressing a "Plastic Pancake"

White PTFE powder is poured into a mold and pressed under high pressure into a cylindrical blank (like a compressed milk powder block).

2. Sintering: High-Temperature "Ceramicization"

The blank is fired in a furnace at 360℃, melting the powder into a solid plastic rod (Figure 2).
Characteristics: This step gives PTFE a smooth, non-stick surface.

3. Turning: Rotary Cutting of Thin Sheets

The plastic rod is rotated on a machine tool, and a spiral cutter is used to cut a strip-shaped thin sheet (Figure 3). This strip is the prototype of the sealing ring.
Advantages: 10 times faster than mold production, suitable for small-batch customization.

III. Manufacturing of Metal Composite Sealing Rings (e.g., Skeleton Oil Seals)

1. Building the "Iron Skeleton":

A stamping machine cuts a metal sheet (stainless steel/carbon steel) into a circular skeleton (Figure 4), and the surface is sandblasted.

2. Rubber "Inlay":

The skeleton is fitted into a mold, liquid rubber is injected, and the rubber bonds with the metal under high temperature and pressure (Figure 5).
Challenge: The rubber and metal must adhere firmly, otherwise the seal will "detach."

3. Fine-tuning the Lip:

After cooling, the seal is removed and the sealing lip is trimmed with a knife (Figure 6) to ensure uniform thickness.
Quality Inspection: Check with a magnifying glass for air bubbles and missing adhesive—one pinhole equals scrap.

IV. Special Process Finishing Touches

Spring Support: A small spring is embedded inside the oil seal lip (Figure 7), automatically wound and fastened by the machine.
Surface Coating: Food-grade sealing rings are coated with Teflon for a smoother, more wear-resistant finish.
Laser Marking: The model and brand are engraved on the ring using a laser (Figure 8) to prevent counterfeiting.