Nappy production line<br><font size="7">365 days lubrication-free continuous operation<br>thanks to drylin® linear axis</font>

Nappy production plant

365 days of lubrication-free continuous operation thanks to drylin® linear axis

Dry-running linear systems in nappy production lines

The output of these highly complex nappy production systems has tripled in recent years without any investment in new machines. On the one hand, this is due to very high system availability and, on the other, the production process is subject to continuous improvements. In addition, set-up times have fallen significantly. Various products from our extensive modular linear bearing programme, which leaves nothing to be desired, ensure the necessary flexibility when changing over the different formats. They withstand the harsh everyday operating conditions in the long term.

Profile

More application examples

Products used

drylin® Easytube single-tube guide

drylin® SHTP - the economic one

drylin® SHT - the standard

drylin® SLW lead screw linear module

drylin® W WS double rail

drylin® W Hybrid bearing WJRM-02-BB

Problem

Nappies are manufactured in what is known as a one-step process. This means that all the required raw materials are available in the form of rolls or powders and are combined and packaged in a single process step to create the end product. ONTEX MAYEN GmbH is the market leader in the field of private label hygiene products. It offers a wide range of products for the baby, feminine and adult hygiene sectors. At the Mayen site, baby nappies in all sizes and variations are produced exclusively on a total of eleven lines and sold almost worldwide.
The nappy manufacturer serves many customers. It must therefore guarantee system safety and flexibility in production and packaging. Every order or size change results in changeover times or adjustments. There are typically four size changes a week per line, which equates to over 200 size changes a year. But the requirement profile goes even further. This is because the systems run around the clock, seven days a week. This means that they are in continuous operation almost 365 days a year. Due to the high process speed, high dynamic loads are also applied to the systems. These are up to 600 m/min.
Due to the process, the ambient temperature in the production hall tends to be warm. However, there are no extreme temperatures. Superabsorbents and cellulose are processed, which cause a relatively high amount of dirt and dust. Superabsorber also behaves in a similar way to sand, so that soiling occurs due to friction effects. To summarise, it can therefore be said that the systems and the machine elements installed in them are subject to extremely high loads. Nevertheless, they must function absolutely reliably under all circumstances.

Solution

Today, drylin® linear bearings are used for quick and reliable retooling. They are lubrication and maintenance-free, insensitive to dust and dirt, corrosion-free, durable, quiet and lightweight.
Among other things, the drylin® Easy Tube system is used (see pictures 1 - 3 below). The slides, torque support and trapezoidal lead screw nut of the particularly compact linear unit for light adjustment tasks are made from a special high-performance polymer plain bearing. This guarantees freedom from lubricants combined with a low coefficient of friction and very good wear behaviour.
RJUM linear plain bearings replace recirculating ball bearing components in various areas. They are based on highly wear-resistant polymers and are particularly robust and economical.
However, other products are also used in the systems:

Position adjustment
drylin® linear bearings primarily realise positional adjustments such as in the area of the adhesive application points. The adhesive application head is moved reliably via linear guides.

Packaging and visual inspection
Spindle linear units or tables (Figures 4 - 6) prove their worth in the packaging environment or for optical inspection and quality assurance. They are often equipped with spindle clamping to prevent unintentional rotation, position indicators for reliable position adjustment and hand wheel.

Material loading cranes
Another special feature of the systems are material loading cranes, which bring the heavy raw material rolls to the machine (Fig. 7). Hybrid bearings from the drylin® W-programme are used to move the overhead cranes. They offer a combination of gliding and rolling. The coefficient of friction is minimised, adjustment and drive force are kept as low as possible.

Overview of drylin linear technology

Overview of drylin linear axes with lead screw drive

"Downtimes have risen continuously in recent years. We have adapted the systems to the constantly increasing requirements without the need for exorbitant investment. The maintenance and lubrication-free linear products are a key factor that has enabled us to achieve this flexibility."

Thomas Heege, Head of Technology at ONTEX MAYEN GmbH

Figure 1: Format adjustment of the sensors for web centre control using the drylin® easytube SET-25 spindle linear unit. The spindle is reliably protected by the robust aluminium tube.

Figure 2: The sensor adjustment for film web centre adjustment is positioned using the drylin®-linear unit Easy Tube SET-25.

Figure 3: Format adjustment of pneumatic cylinders for cleaning blow-off using drylin® linear unit Easy Tube SET-25.

Figure 4: Centre adjustment of a four-lane 90° deflection using the drylin® lead screw linear system SHT-12-AWM for non-woven webs. A total of eight systems are in use.

Figure 5: Compact format adjustment for adjusting the inspection camera using the drylin® lead screw linear system SHTP-12-AWM.

Image 6: The SLW-2080-AWM linear spindle tables ensure synchronised height adjustment for pressing the packaged nappies into boxes.

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