Nested Zero Waste Ear Application for Diaper Manufacturing
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Solution Overview
Problem
In the manufacturing of disposable hygiene products like diapers, the existing methods for applying ear webs result in significant waste due to inefficiencies in web processing, where incoming rolls are not fully utilized, and recyclable materials are commingled, requiring intensive separation processes.
Innovation Solution
A method and apparatus that use a rotary knife or die to create trapezoidal ear webs, which are then rotated to ensure correct orientation using an ear turner assembly, allowing for zero or minimized waste by synchronizing the cutting and application process, and applying these ears to a chassis web using vacuum transfer or intermittent adhesive.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of substance
If traditional slip-and-cut applicators are used to apply ear webs, then ears can be applied to the chassis web, but significant material waste occurs because incoming rolls are not fully utilized
Solution Approach 1:
The ear web is divided into individual ear segments along predetermined break lines through a multi-stage cutting process. A first cut creates a leading edge, a second cut creates a trailing edge, and a third cut creates a lateral edge, resulting in discrete ears that can be applied without waste while maintaining high productivity
Solution Approach 2:
The ear web is pre-cut and pre-formed with predetermined break lines before application to the chassis web. This preliminary segmentation allows the material to be fully utilized as ears are cleanly separated and applied without generating waste material that would otherwise need to be discarded
2Loss of substance
If recyclable materials are harvested from defective products at the end of the process, then waste can be recycled, but the separation process is intensive and inefficient
Solution Approach 1:
Defective ears are extracted and removed from the web at the point of detection, immediately after the cutting process. This early extraction eliminates the need for complex end-of-line separation processes, as defective material is removed before commingling with good material, simplifying the recycling workflow
Solution Approach 2:
Defective ears are identified and removed preliminarily during the application process rather than at the end. This preliminary removal of defective material prevents commingling of recyclable materials, eliminating the need for intensive separation processes later in the workflow
3Productivity
If ear webs are cut and applied at high speeds to match production rates, then productivity increases, but the mechanical integrity and operational capabilities of the applicator must be significantly improved
Solution Approach 1:
The cutting process is segmented into multiple discrete cutting actions (first cut, second cut, third cut) rather than attempting to cut all ears simultaneously. This segmentation allows each cutting operation to be performed at manageable speeds while maintaining high overall productivity through continuous processing
Solution Approach 2:
The applicator system incorporates dynamic speed adjustment capabilities where the ear web feed speed and anvil rotation speed can be independently controlled and synchronized. This dynamic control allows the system to operate at high speeds while maintaining the mechanical integrity required for clean cutting and proper ear application
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach enables the application of non-square ear webs with zero material waste, improving operational efficiency and reducing the need for extensive waste recycling by ensuring all incoming material is utilized, thus enhancing the mechanical integrity and operational capabilities of diaper converters.
Implementation Method 1
a synchronized vacuum anvil
Implementation Method 2
A method and apparatus that use a rotary knife or die to create trapezoidal ear webs
Implementation Method 3
which are then rotated to ensure correct orientation using an ear turner assembly
Implementation Method 4
applying these ears to a chassis web using vacuum transfer or intermittent adhesive
Data Source
AI summary
The present invention provides a process wherein a rotary knife or die, with one or more cutting edges, turns against and in coordination with a corresponding cylinder to create preferably trapezoidal ears. Ear material is slit into two lanes, one for a left side of a diaper and the other for a right side of a diaper. Fastening tapes are applied to both the right and the left ear webs. The ear material is then die cut with a nested pattern on a synchronized vacuum anvil. The resulting discrete ear pieces however, due to the trapezoidal pattern of the ears, alternate between a correct orientation and an incorrect (reversed) orientation. The reversed ear is required to be rotated 180° into the correct orientation such that the ears and associated tape present a left ear and a right ear on the diaper.