In high-speed production environments even the smallest components, like doctor blades, can have a significant impact
on overall performance. One often overlooked issue is doctor blade fatigue, also referred to as “mechanical creep”. Understanding fatigue and how to spot signals that it is occurring will improve print quality, press efficiency, and blade life.
What Is Doctor Blade Fatigue?
Doctor blade fatigue is the gradual reduction in stiffness of the blade as it continuously presses against the anilox roll. When the blade is new, it has a certain initial stiffness. Over time, as it remains under load, it loses that stiffness—this difference between its original and eventual stiffness is what we call fatigue.
Why Does It Matter?
When a doctor blade starts to fatigue, it doesn’t wipe the anilox roll as effectively. This leads to changes in the ink film thickness and consistency. Press operators might try to fix this by increasing blade pressure, but that actually makes things worse. More pressure just flattens the blade further, causing poorer metering and even faster blade wear. The end result is a decline in print quality and more frequent blade changes.
What Can You Do About It?
You can solve the fatigue problem by using doctor blades made from materials designed to minimize mechanical creep. For example, TruPoint Edge & Polylam from Flexo Concepts have very low creep (5% and 10% respectively) as measured by the difference between their initial and eventual stiffness. This means consistent stiffness and a stable contact area, which preserves print quality and reduces the need for constant adjustments.
When it comes to printing with doctor blades fatigue can quietly decrease your quality and efficiency. Choosing doctor blades that maintain their shape and performance under pressure is key to getting consistent, high-quality results.
