11
Operating Techniques Formech FM660
Heaters
The powerful infrared ceramic heaters are designed to heat the plastic rapidly without burning the
surface. The time required to heat the plastic sheet remains fairly constant once the heaters have
reached their operating temperature.
The movement of the heater is manually controlled. The operator is able to send the heater partially
back to check the condition of the plastic and then bring it forward to continue the heating process. This
action will not interrupt and restart a timed heating cycle unless the time has elapsed and the alarm
already sounded. Always use the red handle to move the heater.
The heater control system uses 'simmerstats' to vary the output of individual zones as displayed on the
heater front panel. There are six controllable heating zones, three concentric zones, the outer zone is
split into four zones to enable users to balance the heating and allow for sides drafts etc.
After the required zone heat level, as set on each simmerstat, has been reached, the corresponding red
neon indicator will go off. This indicates that the zone is not drawing any power. As the elements cool
down the power cuts back in and reheats the zone.
The individual zones may be set up to provide an even spread of heat. To achieve the best results set
the inner zones lower than the outer zones and remember that the rear of the heater will always run
hotter than the front. Having set the heaters, slight adjustments may have to be made depending on the
mould design, plastic type / thickness / colour and the machine & environment temperature / conditions.
When using the full forming area it is advisable to keep the central zones 1 and 2 turned down slightly.
These areas retain the heat the most and the outer zones lose the heat the fastest. When using
reducing frames the zones not in use should be turned down. Always push heaters over rear heat
shield when not heating plastic.
Heating cycle times vary according to a number of factors. With a little experience, timings may be
easily estimated. Some plastics such as styrene have a wide tolerance to heating times giving
consistently good mouldings. Care must be taken with materials, which are Hygroscopic (retain
moisture) such as ABS, as the surface will blister if the material has not been pre-dried.
The moulding should be formed when the plastic is sufficiently ‘relaxed’ or at its ‘plastic transition’
temperature. A properly heated sheet will give an excellently defined moulding. If the sheet is not hot
enough while forming the moulding will not pick up all the detail from the tool.
The times below were recorded using styrene at an ambient temperature of 20°C with the machine at
operating temperature. Please note that these times are a guide only.
Various factors will affect the heating time including the colour and surface finish of the material.
1.5mm Thick = 45 seconds
2.0mm Thick = 95 seconds
4.0mm Thick = 170 seconds
