Essential Guide to Protective Films for Stainless Steel Sheets: Stretching, Cutting & Surface Protection

1) Standard Protective Film – Basic Surface Protection

This type is used for commonly processed finishes such as:

• Hairline/Brushed surfaces

• Satin/Matte surfaces

• BA mirror surfaces

Different finishes require different levels of adhesion:

• Brushed / matte surfaces → typically need higher adhesion (around 70g or above)

• Mirror BA surfaces → require low adhesion (below 40g) to avoid leaving residue

Matching adhesion to the material and surface smoothness ensures the film stays firmly in place without damaging the steel.

2) Laser-Cutting Protective Film

Stainless steel used for laser cutting must be covered with specialized laser films.
Standard protective films cannot withstand the heat and precision required in laser processing.

There are two primary categories:

• CO₂ laser films

• Fiber-laser-specific films

Why this matters:
Different laser types—and even different wattages within the same category—affect the film’s behavior during cutting. As modern fiber machines become increasingly powerful, both film thickness and adhesion must be adjusted to suit the equipment and the surface finish.

Failing to choose the correct film can cause burn marks, melting, poor cutting quality, or adhesive residue.

3) Stretching/Deep-Drawing Protective Film

For parts requiring forming, stretching, or stamping, the film must provide:

• High elasticity and toughness

• Suitable adhesion (not too low, not too high)

• Adequate thickness to prevent tearing

Low adhesion causes the film to lift during forming, offering incomplete protection.
High adhesion makes the film difficult to remove after deep drawing—often consuming excessive labor.

A balanced choice ensures smooth processing and clean removal.

4) Specialized Application Methods

Depending on the production process, the film may be applied in several ways:

• Single-sided film

• Double-sided film

• Double-layer film

• Striped or segmented application

These variations help accommodate CNC machining, bending, polishing, and multi-step processing.

Before mass production, it is strongly recommended to perform:

• Peel tests

• Trial stretching

• Trial laser-cutting

Even a high-quality stainless steel batch can be compromised by improper film selection or application—leading to rework, delays, or in severe cases, material scrap. A few minutes of testing can save hours of trouble later.