Fusing Process and Different Features

Fusing Process and Different Features

Fusing process is one kind of alternative method of fabric joining which is widely used to attach the interlining.
At present, apparel manufacturing cannot be imagined without a fusing process.
In the fusing process cut components or separate parts of a lay (blocks of components) are fused with interlinings that are coated with thermoplastic resin.
Fusing certain components creates strength and stability and improves the shape and crease resistance of a garment.
The fusing of the components is usually performed in a cutting room as this process must be performed after material cutting and before the final operations in a cutting process (quality control, sorting and bundling of cut components).

Each apparel manufacturer persistently attempts to manufacture garments with instant sales appeal. Nevertheless, one of the vital materials, fusible interlining, which is utilized for nearly almost every component of outerwear, has no sales appeal because it is imperceptible to the consumer.

The method of fusing interlining to the garments started in Europe in about 1950 and in Japan in about 1960. Today, about 80% of all garments necessitate the use of interlining.

Fusible interlining is the process where the wrong side of the fashion garment panel is fused with a thermoplastic resin and can be bonded with another strip of fabric by the proper application of pressure and heat at a specific temperature and time. 

The fusible interlinings improve the appearance of finished garments through the Stabilisation and control of crucial regions of the garment.

Strengthening of particular design features.

Without much change in the draping quality of the top cloth.

Maintaining the crisp and fresh look of the base fabric.

Fusing Presses and Their Characteristics:

The fusing process is performed by special fusing presses. They can be divided into two groups according to the way they perform the work process: discontinuous work process (flat) fusing presses and continuous work process fusing presses. 

Discontinuous work process fusing presses realize sequential, separated from each other fusing process. They are less productive and are suitable for small and medium production units. 

Continuous work process fusing presses enable an ongoing process by moving the components on a conveyor belt. They offer a higher level of productivity and are more energy-efficient. Because of these advantages, continuous fusing presses are designed for different power production units and used more often.

Discontinuous work process fusing press: 

The discontinuous fusing press is a generally flatbed, which has a heating zone with two work surfaces. 

The other arts are handle, head, and buck. Depending upon the construction, there are two ways in which the work surfaces may move to open the press such as an upper surface which folds sideways (fusing plate press) and an upper or lower surface, which is moved whilst maintaining its parallel position. 

The discontinuous fusing press is flexible for a range of materials, needs low maintenance, which is designed for low to medium-sized production requirements. 

Continuous work process fusing press: 

The operation of this type of press (see Figure) depends on a continuously moving conveyor belt, which moves the face fabric and its interlining components in and out of the heating chamber. 

The heating chamber of an advanced continuous fusing press consists of several (up to 7, 9 or 12) individually controlled separate heating zones for the even distribution of heat. 

The temperatures for the upper heating zones (which heat the interlining) and the lower heating zones (which heat the face fabric) can be adjusted separately and precisely using a special heat control system. 

The long heating chamber with its several heating zones extends the heating time and ensures a gradual temperature increase so that the cut components can be fused perfectly even under lower temperatures, avoiding fabric shrinkage and fading.

The heating capacity and the geometry of the heating chamber determine the material to be fused. Lighter fabrics require lower heating capacity and shorter heating chambers with fewer heating zones. 

The main heat should come from the face fabric side, in order to have the melting resins flow towards the face fabric. 

For heavier fabrics, higher heating capacity and a longer heating chamber with several heating zones are needed. Heating from both top and bottom sides, with separate thermo control, ensures the correct temperature balance. 

Purpose of Interlining

To make sewing easier and to increase throughput: Since the speed of sewing machines is very high, the material must be in perfect structure and shape before sewing. Therefore, operator efficiency could improve. Suppose if interlining is fused onto the material. It keeps its shape, therefore saving time and labor.

Maintaining shape and improving the appeal of the garment: The interlining fabric improves the garment appearance while preserving the form of the garment.

Making a functional, easy to wear product: By the use of a permanent press method, the sewing of garments becomes easy and a good quality product is made, which is easy to care and easy to wear. The main objective of pressing is to enhance the look and durability of the garment shape.

Requirements of Fusing

The laminate formed by the fusing process should demonstrate the aesthetic properties necessary for the finished garment.

The bonding strength between the base fabric and interlining fabric of the laminate should be satisfactory to bear up handling during further processes in the manufacturing sequence.

Fusing should take place without either strike-through or strike-back taking place.

The fusing process should not cause thermal shrinkage in the main fashion fabric after fusing.

Fusing Process

The elements of the fusing process are temperature and pressure, applied over a particular period of time on a fusing machine. 

By increasing the temperature at the ‘glue line’, the resin changes its state from a dry solid to a viscous fluid. 

By applying adequate pressure, the molten state of resin will adhere to the fibers in the main fashion fabric as well as fibers in the interlining. 

During the cooling process, the resin re-solidifies and forms a durable bond between the two fabric panels. 

The heat has to go through the fabric to activate the resin, and this necessitates a certain holding time, which differs based on the construction of the fabric and the type of resin.

Characteristics of Fused Laminates

Apart from the outer fabric panel of the garment, the factors that decide the characteristics of the fused laminate are-

• The base fabric of the interlining
• Type of fusible resin
• The pattern of application of resin to the base cloth

Base Fabric

The base fabric, otherwise called a substrate, is an interlining fabric on which the thermoplastic resin is coated. They are manufactured in a range of woven, knitted and nonwoven forms from natural or synthetic fibers. Irrespective of the interlining fabric construction and fibers used, the base fabric influences the following properties of the finished garment : 

• Handle and bulk
• Shape retention
• Shrinkage control
• Crease recovery
• Appearance in wear
• Appearance after dry cleaning or washing
• Durability

Resin

The resins are applied to the base fabric for bonding. While the resins are exposed to pressure and heat for a specific period of time, it becomes the bonding or adhesive agent between the interlining and the top fabric. 

During the continuous application of pressure and heat, the molten resin could penetrate into the top fabric and while cooling the solidification of molten resin forms a bond between the interlining fabric and the top cloth. 

Conditions to meet resin-

Upper-limit temperature – The resin should be converted into a viscous state at this temperature and should not damage the top fabric. While this temperature varies based on the consumption of the top fabric, it hardly ever exceeds 175°C.

Lower-limit temperature – This is the minimum temperature at which the resin starts to become a viscous state. For most fusible interlinings, this is about 110°C, and is slightly lower for fusible interlining used for leather materials.

Cleanability – The adhesive characteristics of the resin have to be durable enough to sustain repeated dry cleaning or washing operations during the life of the garment.

Handle – The resin should contribute to the requisite handle and drape of the top cloth and should not act as a stiffening agent on the final garment.

Coating System

The coating is the method in which the thermoplastic resins are applied to the substrate material. Generally used coating methods are 

Scatter coating – This method utilizes electronically controlled scattering heads to set down the resin onto the moving fabric.

Dry-dot-printing – The resin is printed onto the fabric through an engraved roller having microgrooves to retain the resin.

Paste coated – The net-like structure is formed by heating the resin and then it is laminated on the fabric by applying heat and pressure.

Methods of Fusing

Reverse fusing – In this technique, the outer fabric is placed on top of the fusible.

Sandwich fusing – This method could be carried out only when the heat is applied from both the top and bottom of the fusible like in a horizontal continuous press machine.

Double fusing – In this method, two types of interlining are fused to the outer fabric in a single process like the fusing of shirt collars and men’s jacket fronts.

Control of Fusing Quality

Fusible interlinings are accurate products and it is important that they are fused on the correct equipment under the strict control of parameters. Factors affecting fusing quality are 

Temperature

Time

Pressure

Peel strength

Dry-clean/wash