Making Nonwovens – from feedstock to final product
The production of nonwovens is a specialized, highly technical process applying a variety of technologies. Numerous industries use nonwovens in countless applications ranging from the production of personal hygiene items all the way through to the automotive industry. Sandler, a leader in the field of nonwovens, is always striving to innovate the production process. In this blog, we will glance behind the scenes and highlight the steps leading to a high-quality product.
It all starts with the fibers
The very basis for most types of nonwovens is fibers. As the feedstock for nonwovens, fibers play a crucial role regarding the properties of the final product. Sandler predominantly uses synthetic fibers such as Polyester and Polypropylene but also Viscose and other raw materials from sustainable sources. Depending on the intended application, we select fibers having different characteristics and blend them to achieve the desired outcome. Another criterion in selecting fibers is the fiber titer - it describes the fineness - or thickness - of a fiber and has a direct influence on softness, strength and function of the nonwoven. At Sandler, innovation and environmental awareness have gone hand in hand for a very long time. Decades ago, we abandoned traditional production methods in favor of the environment. Today, we are constantly on the quest for new, efficient and sustainable raw materials, and in our portfolio, you will find numerous products with recycled content or made from sustainable and biologically degradable fibers.
Fiber preparation – the fundament of nonwoven making
The first step in the production of nonwovens is the preparation of the fibers. It commences with the opening of the fiber bales, intending to separate and homogenize the fibers and form a uniform precursor for the nonwoven production. For this, we use specially coordinated machine units. This step is crucial for an even distribution and mixing of the different fibers and is also decisive for the quality of the finished nonwoven.
From fibers to nonwovens – the many ways of making nonwovens
Next is the very process of turning a layer of fibers into a nonwoven. Depending on the desired outcome, there are several ways to make a nonwoven. At the heart of almost every nonwoven production is a unit called carding machine, or card. A carding machine works like a giant round hair brush and is used to disentangle, clean and intermix the previously separated fibers and to transform them into a continuous web, or sliver. Subsequently, the desired volume is set.
Up to this point, the fibers supposed to form a nonwoven fabric, are only loosely connected to each other by friction. To turn this loose web into a nonwoven, there is a choice of technologies. The process of needle punching uses barbed hooks to create a mechanical bond between the fibers, whereas thermal bonding and thermal point bonding apply heat to fuse fibers together. Spunlace, in contrast, is a process that uses fine, high-pressure water jets which penetrate the web to create a mechanical bonding by entangling the fibers with each other. This process is also known as hydro-entangling. All of these processes have in common that there is a web to be bonded one way or another to form a nonwoven fabric. Each of these processes results in specific material characteristics that are decisive for their respective applications. A very special process is meltblown, where, in a vertical setting, melted polymers are extruded through a die to form very fine fibers. On their way down, these fibers are stretched and cooled by an airflow. Subsequently, the resulting nonwoven is collected on conveyor belts and rolled. Given its extremely fine fibers, meltblown nonwoven is particularly suited for the use in filtration media for air or liquid filtration.
Converting: turning rolls and sheets into products
The process doesn’t end with the manufacturing of the nonwoven. Our customers convert nonwovens into a broad range of products optimally suited to the requirements of the respective industry. Originally produced in roll or sheet formats, nonwovens may be converted in many ways. Slitting or die cutting into form and size, sheeting and folding, pleating, printing, impregnating, or perforating. And of course, nonwovens may be ultrasonically welded, molded, sewn or otherwise put into shape to form e.g. accurate automotive or upholstery parts.
Precision, Progress and Innovation – the Sandler way of producing nonwoven
The production of nonwovens a complex process that requires technical expertise and state-of-the-art machinery. Sandler has established itself as a leading manufacturer by offering not only high-quality products, but also innovative and sustainable processes. Starting with the assessment of your needs, the selection of the right fibers all through to web formation and bonding – at Sandler every step is carried out with the utmost care and quality. Ongoing research and development of new materials and processes ensures that we will continue to meet the requirements of the markets and the environment also in the future.
