Dafu

A pressure-sensor diaphragm must flex repeatedly while separating the sensing element from the measured environment. Its thickness and mechanical response influence sensitivity, while temperature, moisture, chemicals, and long-term stress can shift performance. The film therefore has to be selected as part of the sensor design—not as a generic plastic membrane.

Dafu lists pressure-exchanger and sensor diaphragms among the applications for its PEEK film range. The available grades and surfaces allow engineers to begin with a material configuration that matches the intended environment and converting route.

Why diaphragm material selection is difficult

The diaphragm may see pressure cycling, bending strain, assembly preload, cleaning agents, process fluids, and elevated or changing temperatures. A small change in gauge or stiffness can alter displacement. Surface scratches, die-cut defects, or stress around a clamped edge may also become the starting point for failure.

Define the pressure range, pressure-cycle profile, operating temperature, chemical exposure, diaphragm diameter, unsupported area, clamping method, and required sensor output before choosing a film.

Select crystallinity for the complete design

Dafu’s brochure separates PEEK film into semi-crystalline, amorphous, and mineral-filled semi-crystalline categories. Crystallinity affects thermal and mechanical behavior, so the correct choice depends on the intended process and service conditions.

For projects considering a more amorphous option, Dafu’s information on low-crystallinity PEEK film offers a useful starting point. Engineers should not assume that one category is universally more flexible or more stable; they should compare candidate grades in the actual diaphragm geometry.

Control thickness because it changes sensor response

The brochure lists PEEK film from 0.006 to 0.1 mm at widths up to 950 mm, and 0.1 to 0.50 mm at widths up to 1,060 mm. This broad range supports different parts, but a diaphragm requires a tightly defined nominal thickness and tolerance.

Thinner film may increase deflection under a given pressure, but can become more sensitive to handling damage, particles, local gauge variation, and edge defects. Thicker film may provide more mechanical margin while reducing displacement. Finite-element analysis can guide initial geometry, but physical testing remains necessary because clamping and residual stress affect the real response.

Review mechanical data carefully

For the represented 100 μm samples, Dafu reports different tensile and elongation values by PEEK type and direction. These are typical laboratory values, not automatic diaphragm guarantees. A sensor membrane experiences biaxial stress and repeated cycles, which a simple strip tensile test does not reproduce.

The approval program should measure pressure-deflection response, zero shift, hysteresis, repeatability, burst margin, creep, and fatigue after environmental exposure. Record film direction if anisotropy can affect the result.

Include temperature and dimensional stability

The brochure lists a melting point of 341°C for the represented types and provides shrinkage values under defined high-temperature tests. Those figures help screen PEEK for demanding environments, but a sensor’s usable range will also depend on the housing, seal, adhesive, conductor, and calibration method.

Test the complete assembly across the intended thermal cycle. Watch for permanent offset, clamp relaxation, leakage, wrinkling, or changes in sensitivity after dwell at temperature.

Check chemicals, moisture, and surface condition

Dafu describes PEEK film as resistant to chemical solvents, low in water absorption, and resistant to hydrolysis. Compatibility still needs to be tested with the exact fluid, concentration, temperature, pressure, and exposure duration. A material can retain appearance while its mechanical response or interface changes.

Surface finish also matters. Available polished/polished, polished/matte, and matte/matte combinations may influence sealing, bonding, friction, inspection, and coating. Select the surface together with the assembly process.

Build the qualification around the converted diaphragm

Inspect incoming film for thickness, surface defects, and contamination. Then validate cutting, forming if used, cleaning, bonding or clamping, and the final pressure cycle. Sharp die-cut edges, burrs in metal parts, trapped particles, and uneven clamp pressure can defeat an otherwise suitable film.

Dafu’s broader PEEK and PEI engineering-film overview can support early material screening. Final approval should use the exact PEEK grade, thickness, surface, and production conversion route.

FAQ

What PEEK film thickness is best for a sensor diaphragm?

There is no universal thickness. It depends on diaphragm diameter, pressure range, required displacement, clamping, fatigue margin, and processing capability.

Does a tensile data sheet predict diaphragm fatigue?

No. Tensile data supports screening, but a diaphragm needs pressure cycling and environmental testing in its real geometry.

Why does crystallinity matter?

Crystallinity influences thermal, mechanical, and processing behavior. Compare candidate grades under the sensor’s temperature, chemical, and cycling conditions.

Should chemical resistance be tested again?

Yes. Test the exact fluid, concentration, temperature, pressure, duration, and any interaction with seals or adhesives.

What converting defects are most important?

Scratches, particles, local gauge variation, rough cut edges, residual stress, wrinkles, and uneven clamping can affect response or durability.

Evaluate PEEK film in your sensor geometry

Share the diaphragm dimensions, pressure range, temperature, chemical exposure, thickness target, surface, and assembly method with Dafu to plan sample trials.