All axial tests (tension, compression, bending, fatigue) benefit from proper alignment, but it’s especially crucial for:

• Tensile tests of high-strength or brittle materials: Brittle metals, ceramics, or composites have almost no tolerance for bending. Even a small misalignment can cause them to shatter at the grips. The alignment device ensures these materials are tested fairly, often preventing grip fractures and capturing the true tensile strength.
  
• Low-cycle fatigue tests: When applying cyclical loads, misalignment can initiate unintended bending fatigue, causing early failure not due to axial fatigue but due to the bending component. Proper alignment is required by standards (like ISO 23788) for fatigue testing to get valid life data.
  
• Compression tests on slender specimens: If you compress a column or rod, any misalignment can cause it to buckle to the side. The device helps ensure the platens are perfectly parallel and centered, so you measure compressive strength rather than bending or buckling.
• Bend fixture setups: For 3-point or 4-point bending, alignment of supports and loading noses is key to uniform stress. While this device is primarily for aligning the load train of the machine itself, the philosophy extends to fixture alignment. Using the machine alignment device ensures the overall frame is plumb and level, which in turn makes setting up bend fixtures easier and more accurate.

In short, any test where off-axis loading could alter the outcome will see an improvement. Most standardized test methods assume ideal alignment, so using this device helps make that assumption true in practice.