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Monday, 20 August 2012 21:24

How to design an absorbent core

Written by  Super User
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A core is generally made of a mix of fluff and SAP (hereunder we wil not cover special cores made of other materials or so called "fluffless core"). Usually this mix is “homogeneously blended” (HB): it means that SAP and fluff are in the same ratio everywhere along the core. The reason to have an HB core is because SAP works better when it is well mixed with fluff and this improves core general  performances. Of course other type of constructions are possible altough, with current  cores available on the market today, they do not reach performances that HB cores can.

Our recommendation is to design an HB core.

Good products have core with a tridimensional shape. It means that a core with uncompressed fluff show a tipical increased thickness (it means more absorbent material) in the crotch area and especially in the front side. See simplified core design on the right. You can see there is a first layer along the whole core and a second one positioned in the center/front area. These two layers can be two distinct cores but generally it is a single core with a 3D profile (usually it is obtained through a profiled mould filled by absorbent material).

You can identify 3 different zones

        * shallow zone:    it is the lightest area mainly teh back of the core

        * deep zone:    it is the heaviest area and it is located where you need more absorbency

        * transition zone:    it is the area between shallow and deep

Typical basis weights vary from 100 to 200 for shallow zone and fro 400 to 700 for deep zone. As you can easily understand depending on what deep zone shape and basis weights you choose for your core you will have a specific distribution of absorbent capacity from front to back. Pic shows a graph of capacity profile for a specific product obtained through a xls software developed by iResolve named PocketShape

Since we choosed to design an HB core it means SAP will follow fluff distribution (if our equipment is able to do it!!). More SAP we add more absorbent capacity you have distributed along the core with same “capacity diagram” that fluff defined.

A simple spreadsheet like PocketShape will help you to obtain the proper “capacity diagram” and modify your core geometry accordingly.

Of corse you can design a more stylish cores, rounded and narrow at crotch area  but the basic rules we have described here above are the same.

Just their application requires more sophisticated tools to predict core performances.

Read 1463 times Last modified on Thursday, 01 November 2012 10:40
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