The following text is the English translation from Defelsko, which mainly presents the common problems when purchasing the PosiTest AT series adhesion Tester. If you need an accurate understanding, it is recommended to read the English version.
Does your instrument require any formal training to use it? Do you offer 'demo' models?
Can't. Our instruments are designed simply, with easy-to-use menus, full and quick instruction manuals, and helpful videos. In lieu of a demo model, we offer unlimited technical support by phone and/or email with a limited 30-day money-back guarantee.
Is the PosiTest AT factory calibrated?
The PosiTest AT arrives fully calibrated and ready to measure. Includes a long-term calibration certificate traceable to NIST or PTB that documents the actual readings of your instrument recorded in our calibration laboratory against standards traceable to national metrology institutes. Watch out for "certificates" or "attestations of conformity" offered by competitors. These usually do not include actual instrument readings and are often insufficient for common quality requirements.
Is the PosiTest AT portable for use in the field?
absolute. Both manual and automatic PosiTest ATs are designed for long-lasting use through the use of environmentally sealed metal housings, heavy-duty hydraulic pumps, and high-grade industrial pressure transducers. Weatherproof, dustproof and shockproof, it can be used indoors, outdoors and all kinds of weather (meets or exceeds IP 65).
For added practicality and convenience, the PosiTest AT-A automatic model also includes a convenient shoulder strap and rubberized handle.
Does the PosiTest AT include a steel loading device (cart)?
The PosiTest AT is equipped with a self-adjusting trolley, precision manufactured from strong and lightweight aluminum alloy (6061-T6). A low-cost alternative to steel loading fixtures, DeFelsko Aluminum Carts are single-use/consumable items ideal for long-term visual records of testing.
Do you have a suggested adhesive for my particular application?
The ResinLab EP11HT Epoxy Adhesive supplied with the PosiTest AT is easy to use and suitable for testing a wide variety of coating types. In some cases, specialty coatings require more specialized adhesives.
Is the PosiTest AT-A more accurate than the PosiTest AT-M?
The certified accuracy is the same for both PosiTest AT models. However, the fully automated design of the PosiTest AT-A improves measurement consistency by eliminating operator influence on the testing process.
What is the difference between 20mm and 50mm loading fixtures?
A 50 mm dolly is generally recommended for concrete, wood and composite substrates and measured for coatings with expected adhesion values between 50 psi and 560 psi (50-500 psi for AT-M models). A 20 mm dolly is recommended for testing coatings applied to metal or coatings with expected adhesion values greater than 500 psi.
Can I use the PosiTest AT-A on curved surfaces?
yes. Feedback from our customers is that the PosiTest AT gage is suitable for testing most internal or external piping applications greater than 200 mm in diameter. In this case, the maximum glue gap between the surface of the 20 mm trolley and the coating is 0.5 mm. For smaller pipe diameters, a 10 mm or 14 mm dolly can be used, depending on the expected pull-off strength of the coating. For 10mm and 14mm trolleys, the outer diameter can be reduced to 50mm and 100mm respectively.
DeFelsko did not provide or support the use of a curved cart for adhesion testing. In addition to affecting the surface area used to calculate pullout strength and the direction of force lines (generating unwanted shear forces), most adhesion testing standards specifically call for the use of flat pads.
How many measurements can be made on a single battery charge with the PosiTest AT-A?
The rechargeable battery pack (user replaceable) in the PosiTest AT-A can perform over 200 tests on a single charge. As the battery charges, continue testing using the included AC adapter.
What is the lowest adhesion strength that the PosiTest AT-A can measure?
When used with a 50mm dolly, the PosiTest AT is activated until a 50 psi activation pressure is reached. The instrument starts to calculate and display the pull rate only after the start pressure is reached.
While the AT-M models can get readings below this initial pressure, the AT-A automatic does not allow the operator to build up cracking pressure very slowly, so it is not suitable for cranking pressures below 50 psi.
Please note that all reported adhesion values (including adhesion values obtained below actuation pressure) are subject to PosiTest AT standard gauge full scale accuracy ±1% (±30 psi, AT-M; ±35 psi, AT-A) Impact.
Is there a faster curing adhesive than the epoxy offered by PosiTest AT?
The versatile epoxy adhesive supplied with PosiTest AT fully cures in 24-48 hours. Operators requiring faster cure times should evaluate other adhesives for compatibility with the coating under test and our aluminum test rig. Cyanoacrylate ('superglue') type adhesives are usually sufficient to reduce peel strength.
Can I use PosiTest AT on soft or brittle substrates?
PosiTest AT is designed for rigid structural substrates. Flexible substrates can adversely affect test accuracy and repeatability. Additionally, using the PosiTest AT to measure the adhesion of coatings applied to brittle substrates often results in substrate failure, making it difficult to quantify coating-substrate bond strength.
