Disposable diapers are produced in a continuous process. A baby diaper machine is typically between 20 to 45 meters long, depending on the speed and the complexity of the product to be made. When we take into account the primary peripheral equipment, a typical machine will be from 6 to 13 meters in width. Typical diaper machine speeds range between 200 to 600 diapers per minute, though some of the larger companies have machines running at 1,000 pieces per minute. The fastest machine I have personally seen was running at 950 diapers per minute.
The process starts at the mill, where a sheet of pulp is fed into a rotary mill and is converted into fibers (from 2.3 to 2.7 mm in length). These fibers are transported into a forming pocket using a vacuum generator that is also called the “dust collector”. As the fibers are produced, they are mixed with a super-absorbent within the drum former. The drum former usually holds between 8 to 12 pockets, depending on diaper size and the diameter of the drum. The mix of pulp and powder coming out from the drum is called “the pad” or “the absorbent core”. Once the pad is formed, a layer of tissue (or light weight non-woven) is placed on the top, bottom or around the whole pad. The pad is then compressed using a debulker roll and then it is cut into individual pieces of pad (unless the pad was made in a non continues drum former). In the next step, a poly film or cloth-like material is added at the bottom of the pad (or laminated on line) and non-woven material is added at the top.
Frontal tape is glued to the poly film or cloth-like backsheet, using a cut and place applicator, before it is added to the bottom of the pad. In order to glue all these materials, hot melt is used in the form of multi-lines or spray. Specialty glue is also used for pad integrity, particularly when the pad is very thin; this help reduce incidence of breaking apart of the diaper when it is wet. Elastomerics are also added at this point to provide stretch to the waist and the leg area – they are glued with hot melts. Typical elastomerics used in a diaper are Lycra (Spandex), polyurethane or polyesther foam.
The non-woven top sheet can be made of one or more pieces, depending on the features to be added to the diaper. For example, diapers can be with or without leg cuffs. Typical nonwovens used in a diaper are Spunbond and Thermobond or a combination, such as SMS (spunbond-meltblown-spunbond). The top sheet is made of hydrophilic nonwoven and the leg cuffs are always phobic, in order to provide water resistance and to stop leakage. The next step in the manufacturing process is addition of lateral tapes. They are applied using another cut and place applicator. Tapes can be the standard adhesive type, made of polypropylene, or they can be mechanical tapes, like the hook and loop (originally called and patented as “Velcro”) tapes. After the tapes are added, a die cutting system trims the leg area of the diaper and discards the waste, using a vacuum system. These trims are later recycled in a different process to make plastic pellets, to be transformed into garden houses or even funeral caskets inside linings.
A visual system is frequently used for automatic inspection just after trimming, before the folding of the diaper. The diaper is carried on to a folding process and then it is cut into individual diaper pieces, is inspected and is finally stacked into a plastic bag for its final sealing and packing. You can visit “Machine Photos” if you want to take a look at pictures of baby diaper machines from different vendors. If you want to learn how to control quality in the process of diaper manufacture, click: Quality Control Systems. If you want to see a process chart, please click: Diaper process. If the language is starting to be a bit technical, here you can find a list of technical definitions to help you better understand the language used in the diaper industry: Technical Dictionary. For a nice short video showing an actual diaper factory in operation, please use this link: diaper machines. If you want to really understand the diaper manufacturing process in great detail, you may want to hire my consulting services. I have an intensive three day seminar that includes everything you need to know to understand the diaper manufacturing process, with many pictures and videos where I explain all comparative technologies and provide Excel and Power Point presentations to help you with your diaper factory economic feasibility project. With many such presentations in 4 Continents, I am the world expert in this topic. For more information please visit: Richer Investment.