Sterlco SF1000 Gravimetric Additive Feeder - Manual (Page 11)

11
4.0 Operation
4.1 General
The Sterling SF-1000 adjusts itself automatically once new process data - product weight
and required additive percentage - is entered into the controller.
4.1.1 Operation Modes
The device can operate in four (4) pre-selected operation modes:
1. Mode "0"- Gravimetric loss-in-weight operation mode (regulated speed/machine
feeding time)
The motor speed is regulated on-line by the controller according to the required dosing
rate, while the feeding time is determined by a signal (dry contact) from the injection
machine, synchronized with the injection cycle, as the average value of the last injection
shots (see notes).
2. Mode "1"- Gravimetric loss-in-weight operation mode (regulated speed/constant
set feeding time):
The motor current is regulated on-line by the controller according to the required dosing
rate, while the feeding time is constant, as set by the operator.
Start time is synchronized with the injection cycle by a signal (dry contact) from the
injection machine.
This mode is useful in those cases where the feeding time of the injection machine is not
steady enough, too short, or too long.
3. Mode "2"- Volumetric operation mode (constant speed/machine feeding time):
The motor speed (rpm) is kept constant, as set by the operator, independent of any
variation in the process parameters, while the feeding time is defined by a signal (dry
contact) from the injection machine, synchronized with the injection cycle (see note).
4. Mode "3" - Volumetric operation mode (constant speed / constant time)
Two alternatives (sub-modes) are available:
1. Standard Volumetric mode: Both speed and time are constant, as set by the operator.
This mode is applicable if any one of screws 1-4 is selected (not the micro).
2. Micro Volumetric mode: Operator sets motor speed and desired number of screw
revolutions per injection cycle according to required batch weight (instead of feeding
time, as in standard mode 3).
This mode is applicable only if micro screw (No "0") is installed and selected.
Using this mode enables very low dosing level, up to 2-3 granules per shot.
Possible operation modes are shown in the following table:
Operation Mode Dosing Time Motor Speed Revs/INJ shot
Applicable
screws
0 Gravimetric
Equal to IMM
feeding time
Controlled
automatically by
MB %
0,1,2,3,4
1 Gravimetric
Set by
operator
Controlled
automatically by
MB %
0,1,2,3,4
2 Volumetric
Equal to IMM
feeding time
Set by operator 0,1,2,3,4
3
Volumetric
Standard Set by
operator
Set by operator 1,2,3,4
4 Volumetric Micro Set by operator Set by operator 0 (micro)
For more information concerning selecting the correct operation mode, see section 4.4