The Fusing Technology, Fusing Parameters and Fusing Process Flow

Nowadays most of the garments, be it a shirt, a pant, a blouse, a jacket or even jeans, we can always find fusing in it and often I get to hear this question on how to make a proper fusing as the types of fabric, base cloth never remains the same. And to know that, first of all, we need to know about the basic of fusing technology, the importance of it, the fusing parameters that control fusing quality and t the fusing process.

What is fusing?

Fusing is an alternative process of fabric joining which is widely used to attach interlinings. The fusible interlining consists of a base cloth, which may be similar to that used for a sew-in interlining, but will carry on its surface a thermoplastic resin in the form of dots, which will melt when heated to a specific temperature and pressure and flow into the fabric to make the bond.

Not all garment fabrics can be fused, and there may always be some situations where sew-in interlining continues to be used, but in the vast majority of garment making today, fusing is the most common process, the reason being both technical and economic. At present, apparel manufacturing cannot be imagined without fusing process

Why is fusing important?

Fusing has a classic application in the clothing industry for sticking together two pieces of fabric. It can also be used in the automotive industry and furniture industry for applying foams, knitted spacers or nonwoven to leathers. It helps in shortening manufacturing time with a consequent reduction in direct labour cost along with the better look and feel which was not possible in sew-in laminates.

What are the basic fusing parameters?

The four processing components that control fusing are:

#1. Temperature: 
Temperature is the most critical parameter out of the other three. It should be necessarily high enough at the glue-line so that the dry thermoplastic resin would change into a partially molten state so that it can flow between the layers. For each resin, there is a particular range within which the glue would achieve the correct level of flow. Any temperature higher than that would give too much flow resulting in strike-back and strike-through along with a reduction in performance. And too low the temperature, the glue will not melt properly resulting in poor flow and thus poor adhesion. There should be only 5% allowance for the temperature, any variation from it will lead to improper fusing

#2. Pressure: 
There should always be a consistent amount of pressure throughout the interlining and the outer cloth for full contact between them. This will ensure a correct transfer of heat to the glue-line along with even penetration of resin among the fiber of outer fabric.

If the pressure is too high, it will result in strike-back and strike-through, and if the pressure is too low there would not be proper penetration and thus lower adhesion.

#3. Time: 
Time is very important as it will allow the temperature and pressure to induce melting of the resin and penetration into the outer fabric in order to produce the appropriate bond. Lesser time will result in improper fusing and greater time may result in strike-back or strike-through. The time cycle of any fusible will be determined by
  • The type of resin used.
  • The type of substrate being used.
  • The nature of the outer fabric and the base cloth being used. 
#4. Cooling:
Cooling is done so that the fused assemblies can be handled immediately after fusing. It can be done by passing the fused laminate through water-cooled plates, compressed air circulations and vacuum.

The first three factors are interrelated with each other and any change in one will result in changing the other parameters also provided a limit to the extent to which one factor will compensate for the other.

The fusing process

Basically, the fusing process requires the elements of fusing i.e. temperature and pressure applied over a particular period of time inside a specialised fusing press. With the rise in temperature at the ‘glue line’ by the electric heating elements of the press, the resin changes its state from a dry solid to a viscous fluid. And only now with the application of pressure, the resin in its molten state would flow among the fibres of the outer fabric and the fusible base cloth, adhering to it. On cooling, the resin re-solidifies in its place forming a durable bond between the two components of the laminate. A minimum amount of time is required for the heat to pass through the fabric and activate the resin which would vary accordingly with the type of the fabric and the resin used. After the fusing is finished it is then cooled down rapidly for handling.

Flow Chart of Garment Fusing Process:

Part of the garment to be fused is spread on a table 
Resinated interlining surface is placed and applied required pressure and temperature 
Resin coating of interlining is melted by heat into the fabric under pressure 
It becomes cool and hard both the fabric and interlining is attached

Also read: Different Types of Interlinings

Soumyadeep Saha

Soumyadeep Saha holds a Master's Degree in Fashion Technology from NIFT, New Delhi. He is also a graduate in apparel production. His area of interest includes Quality Assurance and technology implementations in Apparel Production.

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