Introduction

LW pressure measurement film is designed for 2.5–10 MPa contact pressure testing and medium-pressure distribution evaluation. It adopts a two-sheet structure and produces a visible red image under load, allowing users to assess pressure distribution, contact uniformity, and localized pressure behavior in practical testing environments.

This pressure indicating film is suitable for applications where low-pressure film cannot provide sufficient density differentiation and where higher-pressure film would exceed the required measurement range.

Application Background

In medium-pressure industrial assemblies, it is often necessary to verify not only the applied load but also how that load is distributed across the contact interface.

Typical applications include:

  • sealing surface pressure verification
  • clamping and fastening interface evaluation
  • component assembly pressure checks
  • compression contact validation

In these scenarios, uneven pressure distribution may lead to leakage, deformation, or inconsistent mechanical performance. LW pressure measurement film provides a direct method to visualize these conditions.

Testing Challenge

Medium-pressure contact testing can be affected by several factors, including:

  • surface flatness variation
  • material deformation under load
  • assembly misalignment
  • localized stress concentration

Even when the applied force is controlled, the actual pressure distribution at the interface may vary significantly. Without a visual reference, it is difficult to identify high-pressure zones, weak contact areas, or incomplete contact regions.

LW pressure film converts these hidden conditions into a visible pressure map through color density changes.

Solution Method

LW uses a two-sheet film system consisting of a microcapsule layer and a developer layer.

During testing:

  • the two sheets are placed together with coated sides facing each other
  • applied pressure causes microcapsules to rupture
  • a red color forms where pressure is present
  • color density increases with pressure level

Recommended testing steps:

  1. Place the film between the target contact surfaces
  2. Apply load gradually to the required pressure level
  3. Maintain pressure:
    • approximately 2 minutes for continuous loading
    • approximately 5 seconds for instantaneous loading
  4. Remove the film and evaluate the developed image

This process provides both visual pressure distribution analysis and approximate pressure estimation using density reference curves under matched conditions.

Recommended Film Type

For applications where the expected pressure falls within 2.5–10 MPa, LW is the appropriate selection.

Key characteristics:

  • medium pressure measurement range
  • two-sheet pressure film structure
  • suitable for contact pressure testing and distribution evaluation
  • intended for single-use measurement

This range is widely used in general industrial pressure verification where accurate visualization of medium contact pressure is required.

Result Interpretation

After testing, the developed film serves as a pressure distribution map:

  • darker areas indicate higher pressure
  • lighter areas indicate lower pressure
  • blank areas indicate little or no effective contact

For more precise evaluation, the color density can be compared with standard reference charts under controlled environmental and loading conditions.

Practical Notes

To improve measurement reliability:

  • avoid applying any pre-pressure to the film before testing
  • handle the film carefully to prevent unintended activation
  • maintain environmental conditions within recommended temperature and humidity ranges
  • ensure contact surfaces are clean and free from oil or moisture
  • do not reuse the film after testing
  • evaluate results after 30–60 minutes for stable color development
  • scan or record the result promptly for documentation

Proper handling and environmental control are important to ensure consistent and interpretable results.