shearing force

Term of the Week: Shearing Force

Each week Printwear turns to industry experts to learn more about the terms used in the apparel and apparel decoration industry, as well as the business realm. Contact Printwear's digital content editor, Alexandria Arroyo, if you're interested in the opportunity to be featured. 

This Term of the Week can be found in the full article "Rules for Plastisols," published in Printwear May. To ensure your access to full-length articles and insider tips, subscribe here

Shearing force is the effort required to get the ink from the top of the screen to the bottom of the screen. There are two types of shearing force: shear-stress, force perpendicular to the mesh which is the traditional form of ink transfer; and shear-rate, the more efficient force parallel to the mesh, which is the core of high-shear transfer.

It is always best to use shear-rate (think stroke speed) as to minimize the use of shear-stress (think pressure). With shear-stress transfer, we need to search endlessly to find that magical point between fluid pressure and fluid volume, which most often occurs at a slower stroke speed. With shear-rate transfer, fluid volume, pressure, and speed all run parallel. Accordingly, faster is better, and we can use speed to regulate deposit.

Source: Joe Clarke