Staple fibers are fibers that have been cut into standardized lengths. In contrast, continuous fibers are known as filament fibers. The process of cutting continuous fibers into staple fibers may also be referred to as ‘chopping’. The variance in staple fiber length and the quality of the cut are of crucial importance as they ultimately determine the ability to process the fiber, the quality of the end product and thus the satisfaction of the end customer.
Quality and Experience are Crucial
Poorly cut staple fiber may either be too long or too short. Too long fibers tend to ‘lasso’ other fibers which then create entanglements that make processing of the fiber difficult and lead to web defects. If the fibers are cut too short they may fail to carry substantial load within the web and thus reduce the quality of the end product. Also the condition of the end cut is important: When cutting the fiber the knife deforms the cut end to some degree. However, the ideal cut should be a clean square cut. Other deformations known as the finishing nail head, the elf shoe, the split end, the fused ends, the fused logs or the fused daisy will result in a poor quality of the fiber and the end product. There are two ways in which fibers can be cut: Either it is cut quickly (‘chopped’) or it is sliced (‘stretch breaking’). EuroFibers offers you staple fiber produced through chopping.
Understanding the Process
During the production of staple fiber, the continuous fiber can be crimped to enable processing to non-wovens or for yarn spinning. EuroFibers has a number of specific finishes, which are applied just before crimping and cutting. These finishes have been specifically developed to increase the affinity of the fiber or make it compatible with various processing steps or end applications. The fibers are crimped by a stuffing box crimper and cut with a radial blade cutter. The crimper basically consists of two rolls and a chamber into which the fiber is forced. A bundle of fiber is then introduced between the two roles and forced into the stuffing box. The friction that results as the box fills prevents the fiber from exiting. The pressure and tension from the rolls and the fiber trapped in the stuffing box result in wrinkling of the fiber. What sounds simple in theory requires sufficient experience and expertise in practice: Roll sizes, box geometry, pressure control systems, temperature, wear plates, and construction materials are all factors that determine the ultimate quality of the staple fiber. After crimping the fiber, the fiber is cut into staple fiber using a radial blade cutter. The cutter is composed of a reel that holds cutter blades and a presser roll of equal size. The fiber passes between the reel and the presser roll and is then gently pressed into the cutting edge. Even though these machines are relatively simple they require maintenance, experience, and extensive knowledge in order to produce staple fiber of maximum quality. EuroFibers is specialized in high performance fibers, which are typically very tough and cut resistant. We therefore have to use a special type of knife to be able to cut the fiber, which needs to be replaced quite frequently.
Staple fiber is used in many different industries and offers advantages compared to traditional materials:
One of the most promising future markets for staple fiber based on high performance fibers like Dyneema® is cotton reinforcement. Staple fiber is perfectly capable of being blended with cotton or other natural fibers in order to substantially improve its inherent properties such as durability and strength.
Staple fibers are often used in the production of security paper, specialty paper, or filter paper as they offer superior tensile, burst, bulk, and tear properties.
Staple fiber is used in technical textiles such as non-wowens. One example are needle punch non-wowens that are used in high performance markets such as ballistic protection, shoe soles for safety boots, or high pressure water jet suits.
Para-aramid staple fibers are added to reinforce natural or synthetic rubber for usage in belts or rubber hoses.
Staple fibers improve properties of the base resin or the polymer such as durability or strength.
Staple fibers are also used in concrete where they improve the cracking resistance of the material. Further they are added to roofing materials, coatings, and fillers. Most high performance fibers are produced as continuous filament yarn.