Daikin SUT Injection Molding Machine Super Unit Manual Guide: Pi/Qi Pressure and Flow Commands, I/O Wiring, PMAX/QMAX, Response Parameters, Bleeding and Alarm Repair
SUT Is a Servo Hydraulic Power Unit, Not a Simple Inverter Pump
The Daikin SUT Super Unit for injection molding machines is a variable-speed IPM motor hydraulic system. The controller, motor pump, encoder, pressure sensor and machine hydraulic circuit form pressure and flow feedback loops. The injection molding controller sends analog command voltages; the SUT controls pump displacement Q by motor speed and controls pressure P by pressure sensor feedback.
For repair, do not treat it like a normal inverter pump. Check Pi pressure command, Qi flow command, Po pressure monitor, Qo flow monitor, pressure sensor, encoder, piping, oil condition, overload duty and valve timing together.
Matching Controller and Motor Pump
The manual states that the motor pump and controller are factory tested as a matched pair. Confirm serial numbers and model compatibility before replacement. When replacing the controller, pump or pressure sensor, check H15 flow correction, H30 pressure sensor gain and P07 QMAX. These values strongly affect actual hydraulic output.
Hydraulic Piping and Oil Conditions
The SUT does not include a safety valve. Install a safety valve on the injection molding machine side, normally set to maximum operating pressure plus 2 MPa. Use a suction filter of about 150 mesh and keep suction pressure within -0.02 MPa. Low suction pressure causes air intake and cavitation noise, with higher noise, reduced flow and possible pump damage.
After installation or repair, bleed the hydraulic circuit by moving each cylinder. Long high-pressure manual operation may cause E27 or E17 overload alarms; power off the controller to reset and continue under non-overload conditions.
Main Circuit and I/O Wiring
Main terminals include L1/L2/L3 power input, P1/P2 DC reactor, B1/B2 regenerative resistor and U/V/W motor output. Power, motor and signal wiring must not be mixed. Grounding must be reliable.
The I/O terminal block includes AI1 Pi pressure command, AI2 Qi flow command, AO1 Po pressure monitor, AO2 Qo flow monitor, AGND, pressure sensor signal and supply, ALM_A/ALM_B/ALM_C alarm output, DICOM/DOCOM and digital I/O. Separate analog ground, digital ground, shield and frame ground carefully.
The pressure sensor cable should use the specified connector. The ferrite core is fitted near the controller side, around 100 mm from the terminal, with two turns. Fix the cable near the sensor to prevent pump vibration from damaging the connector.
Pi/Qi and Po/Qo Linearity
Pi is pressure command voltage and Qi is flow command voltage, usually DC 0-10 V corresponding to 0-PMAX and 0-QMAX. Po and Qo are monitor outputs. Pi/Qi must be linear with the injection molding controller’s 0-99.9% pressure and flow settings. Otherwise the machine panel setting cannot accurately control hydraulic output.
If maximum analog voltage is below 10 V, set P05 VMAX and then calibrate PMAX/QMAX accordingly. During service, measure AI1/AI2 and AO1/AO2 at 20%, 50% and 80% settings.
Initial Parameters
P06 is PMAX maximum control pressure. P07 is QMAX maximum discharge flow. The manual emphasizes that P06 and P07 must be set before operation. P07 is not theoretical pump displacement; it is a calibrated value based on actual pump speed and flow. P05 is the common command voltage scale for pressure and flow. WN_L is the overload warning output threshold.
If the same machine setting produces different speed or pressure after replacement, check P06, P07, P05, H15 and H30 before replacing hardware again.
Response Parameters
P08 P_UG adjusts pressure rise response. Higher value gives faster response but more overshoot. P09 P_DG adjusts pressure fall response. P10 and P11 adjust flow rise and fall response. P13 SC_G reduces pressure overshoot. P14 D_TM delays response from standby, allowing hydraulic valves to switch before the pump builds pressure.
P17-P21 are pressure proportional gain and integral time parameters. P22 and P23 set pressure rise/fall ramp time. Tune in this order: oil and piping first, Pi/Qi linearity second, P08-P11 basic response third, then P13/P14/P22/P23 for shock and overshoot control.
Startup and Bleeding
Do not load the pump within five seconds after power on. During bleeding, use manual low-risk operation and observe pressure, flow and noise. Crawling during injection unit movement may be caused by air in the circuit or pressure overshoot. Use moderate pressure and flow-control operation to verify stability.
Alarm Repair
E17/E27 overload alarms are often related to high pressure and high flow duty, long high-pressure manual bleeding, abnormal oil temperature, excessive load, fan trouble or poor cooling. Reduce duty, check oil temperature and cooling, then review aggressive response parameters.
Pressure sensor faults may come from open circuit, short circuit, incorrect wiring, abnormal pressure, poor connector contact or sensor failure. Check supply, signal, AGND, ferrite core and connector before replacing the sensor. After replacement, set H30 PS_G and calibrate with an accurate pressure gauge.
Low flow and loud noise usually point to suction pressure, suction filter, oil viscosity, oil temperature, suction leak or cavitation. Do not hide suction problems by increasing Q_UG or QMAX.
After pump replacement, check P07 QMAX and H15 Q_EV. In monitor mode, verify Qo and compare actual cylinder speed or metering flow.
Service Delivery Checklist
Before delivery, record P05, P06, P07, P08-P11, P13, P14, P16, P17-P23, WN_L, H15 and H30. Also record Pi/Qi, Po/Qo, current, oil temperature and alarm history during mold open/close, injection, holding, metering and ejection.
The reliable SUT repair sequence is: confirm pump-controller matching, check hydraulic piping and safety valve, verify I/O and analog linearity, set PMAX/QMAX, bleed the circuit, tune response parameters carefully and then diagnose overload, sensor or oil-circuit faults from alarm history.