There is a limited range of temperatures that are effective for each type of resin. Too high a temperature causes the resin to become too viscous, which could result in the resin being forced through to the right side of the cloth
Time is the only time element of any value during the fusing process is when the topcloth and fusible are under pressure in the heating zone of the machine .This time cycle for a particular fusible is determined by :Whether the fusible has a high –or low melt resin.
If a high or heavy substrate is being used;The nature of the top cloth being used, thick or thin, dense or open.
When the resin is viscous ,pressure is applied to the top cloth and fusibleassembly to ensure that : 1) Full contact is made between the top cloth and fusible. 2)Heat transfer is at the optimum level.
Enforced cooling is used so that the fused assemblies can be handledimmediately after fusing. Cooling can be induced by various systems. Including water-cooled plates, compressed air circulation and vacuum.
Regular steam pressing machines are not designed for fusing although some fusible are produced for use on these machines. Pressing machines have some serious limitations regarding fusing including –
a. Inability to reach the heat levels required by the majority of resins.
b. The shape and size of the bucks restrict the size of the components which can be fused.
c. Most utility machines are not fitted with programmed controls, which mean that the entire process is operator controlled.
d. If the resin was originally activated by steam heat, the same thing can happen when garments are pressed during their production. This situation can cause serious problems with the stability of the laminates.
Regular steam pressing machines are not the ideal medium for fusing.
Flat bed press
Flat bed presses are purpose built fusing machines produced in a large variety of sizes and which many types of work aids. This type of press has padded top and bottom bucks with electric heating elements in one or both bucks. The bottom buck is static and the top buck is lowered to fuse the assembly whilst under pressure, and then raised after cooling. Most of these machines are fitted with timers and programmed controls and can achieve high levels of fusing quality.
Conveyor belt press
Conveyor belt presses are also called continuous machines because they can be operated without stopping for the loading and unloading of the assemblies. The conveyor belt transports the assemblies through all the processes and the belt speed is adjustable according to the time cycle required. This type of machine is available in different lengths and widths and can be fitted with automatic feeding and unloading systems. A feature of the more modern machines is a microprocessor which can be programmed to control every element of the machines operation.