Fusing Process in Garment Industry:
Fusing process in garment industry is one kinds of alternative method of fabric joining which is widely used to attach the fusible interlining. Fusing is a process in which 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. 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).
Fusing of interlinings in garment manufacturing is a very important process. Fusing process is carried out by applying temperature and pressure over a period of time. The electric heating elements of the press cause the rise in temperature at the glue line which is the interface of resin and outer fabric. The resin is active in that area.
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 strikeback taking place. Since the fusing process involves pressure, there is a risk that pile fabrics may be subject to crushing during fusing.
- The fusing process should not cause thermal shrinkage in the main fashion fabric after fusing.
Factors of Fusing:
In spite of what kind of fusible equipment are used, the process of fusing is influenced by four main factors such as time, pressure, temperature and cooling and these have to be precisely combined to attain the desired results.
1. Temperature: The temperature of the resin should be optimum as high a temperature leads to too viscous a resin and too low temperature does not allow the resin to penetrate into the top fabric.
2. Time: The time period which is a very decisive factor during the fusing process is while the top fabric and interlining material are kept under the influence of heat and pressure in the heating region of the fusing machine. This time of fusing for a particular fusible is based on
- Melting temperature of the resin used
- Weight of the interlining
- The nature and construction of top fabric being used, that is, thick or thin, dense or open
3. Pressure: When the resin becomes viscous after heating at a particular temperature, then pressure is applied to the top fabric and fusible assembly to make sure that
- Full contact is made between the fusible and the top fabric
- Heat transfer is at the optimal level
- There is more even dispersion and diffusion of the adhesive thermoplastic resin into the surface and internal structure of fibers of the top fabric
4. Cooling: Forced cooling is generally used. Therefore, the fused assemblies can be handled instantly after the fusing process. Cooling of fused fabrics could be done by means of several methods such as use of compressed air circulation, water-cooled plates and vacuum. Rapidly cooling the fused assemblies to 30–35°C makes a higher level of productivity.
Methods of Fusing:
a) Single fusing: It is the safest and easiest method in which garment is placed on the right side facing down with the resin side on the garment.
b) Reverse fusing: In this technique, the outer fabric is placed on top of the fusibles.
c) Sandwich fusing: This method could be carried out only when the heat is applied from both top and bottom of the fusibles like in a horizontal continuous press machine.
d) Double fusing: In this method, two types of interlining are fused to the outer fabric in a single process like fusing of shirt collars and men’s jacket fronts. This double fusing process requires the achievement of two correct glue line temperatures in the two layers of resin.
Fusing Machinery and Equipment:
A number of different types of fusing equipment have been developed, providing controlled heat and pressure conditions, such as the flat bed fusing press below, where the garment parts with the interlining placed on top are positioned on the bottom plate and the top plate sandwiches the garment parts and interlining. With controlled heat and temperature, the two garment pieces are laminated together.
The fusing process in garment industry 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 realise 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.
The equipment used for fusing is classified as specialized fusing presses, hand irons and steam presses.
Discontinuous Fusing Press or Flat-Bed Fusing Press:
These are specialized fusing equipment prevailing in a range of types from bigger, floor standing machines to smaller table type models. Mainly this type of fusing press comprises a top padding buck and bottom normal bucks along with the provision of heating elements in one or both the bucks as shown in Figure 1. The bottom buck is normally stationary and the top buck could be raised or lowered to open as well as close the trays, which travel horizontally to feed the components for fusing and remove it after the job is completed.
There are numerous kinds of specialized flat-bed pressing machines, which could have a magazine type or carousel action, which automatically transports the fusing components from the loading point to the fusing zone in a machine and after the process is completed it returns the fused components to the operator for unloading. Flat-bed fusing machines are further classified as vertical action and scissor action closer, in which a vertical action closing type machine is considered more desirable owing to its capability to exert even and uniform pressure throughout the fabric area.
The advantages of flat-bed machines are-
- Simple, less complex and thus easy to operate.
- Size of the machine is smaller and comparatively low cost.
- As the fabric is constantly held under pressure throughout the fusing process, the chances of fabric shrinkage are minimised.
Continuous Fusing Press:
These machines normally have a motorised conveyor belt arrangement for transportation of fusing components through all the processes. The two conveyor belts systems in common use are-
- End-to-end feed: The garment panels are transferred from the loading area, through the fusing and cooling section, finally to the delivery side located at the other end of the machine.
- Return feed: In this belt system, the fused components are returned to the same location where it is loaded. The upper belt transports the garment panels to the fusing processes whereas the lower belt returns the fused panels to its starting position.
The construction and features of a continuous fusing press machine are presented in Figures 2.
The head could be offered in three methods:
- With a direct heating system, the endless conveyor belt transports the fusing components (top cloth and interlining fabric) to the direct contact with a heated drum or plate surface.
- With an indirect heating system, the fusing components are transported into a heated chamber.
- With a low temperature gradient heating system, the fusing components are carried through a preheating zone.
High Frequency Fusing:
Normally in fusing presses, heat is provided by electric heating elements. This confines the thicknesses of fabrics to be fused. If many layers of fabric and interlining could be stacked up and fused concurrently, productivity might be increased by means of high frequency energy. This machine contains an electric frequency generator. The high frequency fusing press is shown in Figure 8.4. The particular kind of polymer present in the thermoplastic adhesive resin system absorbs alternating waves generated by the high frequency generator, which causes the resin to heat up faster than the interlining fabric and the base garment fabric. This leads to better bonding at the glue line without the need of excessive heat.
Hand Iron:
Hand irons are an appropriate method of fusing where the interlinings could be fused at comparatively low temperatures and pressures and in a relatively short time period. But only small components can be fused in this system.
Steam Press:
Normal steam pressing equipment is generally not preferred for fusing although some fusibles are made from these machines. The main limitations of pressing machines concerning fusing are
- Incapability to reach the heat levels requisite by most of the thermoplastic resins.
- Shape and size of bucks limit size of components that can be fused.
- Majority of the pressing machines do not have inbuilt programme control options and hence complete operation should be manually controlled.
- If the resin is activated using a heated steam, a similar process could happen on final pressing during garment production which could lead to serious problems.
Quality Control in Fusing:
Fusible interlinings are accurate products and it is important that they are fused on the correct equipment under strict control of parameters. Factors affecting fusing quality are
- Temperature
- Time
- Pressure
- Peel strength
- Dry-clean/wash
References:
- Apparel Manufacturing Technology by T. Karthik, P. Ganesan, D. Gopalakrishnan
- Garment Manufacturing Technology Edited by Rajkishore Nayak and Rajiv Padhye
- Apparel Machinery and Equipments By R. Rathinamoorthy and R. Surjit
- Guide to Basic Garment Assembly for the Fashion Industry by Jayne Smith
