The barb angle is the amount of degrees the fiber engagingsurface is displaced from a vertical position.
The Foster Formed Barb™ is usually made with a 20 degree barb angle. It is important that the barb angle is precise and does not shift below specification. If the barb angle declines below 10–15 degrees, the fibers will slip off the barb face during penetration through the fiber web, thus affecting key physical properties in the web.
Total Barb Depth
The total barb depth of the needle is measured from the top of the barb to the very bottom. If there is kickup on the barb, it too is included in this measurement.
The total barb depth will determine how many fibers will fit into the barb. Determining the proper total barb depth for aparticular application is critical.
The throat angle is opposite the barb face. It affects the amount and the speed at which fibers fill into the barbs.
The throat length is simply the length of the barb. Larger barbs tend to have longer throat lengths and smaller barbs will tend to have shorter throat lengths.
The throat depth of the needle is the amount of barbthat is below the apex of the triangle.