Identify the primary types of sharpening systems and learn about the features and functions available on these devices.
It's just a piece of rubber. How important can it be? Many screen printers harbor that attitude toward the squeegee—that is, until squeegee-blade imperfections begin to affect the results they achieve on press. The sight of flawed prints is usually the catalyst that sparks the most interest in the squeegee, but spotting trouble so late in the workflow means downtime.
Dull edges, nicks, and uneven profiles are some of the problems that can prevent the squeegee from properly playing its vital role in transferring ink to the substrate. Normal wear and tear from printing can lead to defects in the squeegee blade, as can exposure to inks and chemicals, mishandling, and improper storage. The squeegee sharpener is the tool that screen printers use to restore the squeegee blade's edge so the squeegee can be brought back into action.
Squeegee sharpeners are available in different sizes and configurations (Figure 1) to accommodate a variety of squeegee sizes, performance requirements, and budgets. This article will discuss the technologies in use today.
Squeegee grinders use abrasive components to remove material from the squeegee blade. The two most common types are belt and wheel grinders. Long-belt grinders are the oldest kind. They use a continuous belt that spans the length of the squeegee blade so that the entire length of the blade may be held against the belt during grinding. Wheels or pulleys drive the belt.
The belt grinder is the simplest and least expensive type of squeegee sharpener, according to Sylve Ericsson, executive vice president of Interchange Equipment, Inc. "You put your squeegee on the grinding belt and, depending on the operator, you will have decent quality," he says.
Operator skill is key when using long-belt grinders. These machines are typically manual devices, which means the operator must maintain the blade at the correct angle, ensure that end-to-end free-blade height is uniform, and carefully control the amount of blade material removed during the process.
"When you grind, you should not be taking more than 0.002 in. on each pass," Ericsson says. "That is very difficult to do manually."
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