Formech 450 Installations-, Betriebs- und Wartungshandbuch - Seite 8

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Operating Techniques

Formech 450

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.

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 degrees 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

Heater timer

The timer is intended to assist the production of a large number of similar mouldings.

Operating the switch to the left of the timer panel turns on the timer. The timing value is set by

pushing the '+' or '-' buttons above and below the respective display digits.

The value displayed represents the number of seconds elapsed between the heater being

pulled forward and the sounding of a buzzer. The buzzer indicates that the heating cycle is

complete and the heater may be pushed back.

Timing value may be changed at any time although the new value will not be recognised until

the start of a new cycle. When the heater is brought forward it strikes a micro switch, which

starts the countdown. Pushing the heater backwards or forwards will not interrupt the

countdown.

Bubble moulding

With the 450 it is possible to produce bubble mouldings without using a tool. To form a bubble

the plastic sheet should be heated with the drape table in the lowered position. When the

plastic sheet has heated right through, raise the table, push back the heater, pull down the

pressure lever and hold. Turn on the pump. The plastic will start to inflate.