SC_450 PreciseCoat Conformal Coating Jet_Rev_04.pdf - 第49页

SC-450 PreciseCoat C onformal C oating J et Troubleshooting © 2024 Nordson Corporation 43 Table 6-3 SC-4 50 Troubleshoot in g - Component Based Compone nt Qua lity Troubleshooting Questi o ns Nozzle Size and cleanliness …

SC-450 PreciseCoat Conformal Coating Jet Troubleshooting

Symptom Possible Cause Recovery

Leakage of Fluid

through Weep Hole

Needle assembly or fluid seal

worn or damaged

Disassemble all components from the jet

body. Thoroughly clean fluid from the jet

body bearings and weep hole. Inspect all

sealing and mating surfaces for scratches

and cured fluid. Check the needle

assembly and the fluid seal for

wear - replace if worn. Insure that the

stroke adjust assembly is opened 7-8 turns

prior to tightening fluid body.

Fluid body seal gland scratched

or dirty

Fluid body screws not torqued

properly

Table 6-2 SC-450 Troubleshooting - Set-up Based

Set-up Variable Effect Notes

Fluid

Properties

Dispense

Volume and

Quality

If this is a new process, contact Technical Support for

assistance in process development. If this is a qualified process,

fluid properties may have changed. The fluid may have

exceeded its pot life, or been mishandled or set-up incorrectly.

In addition, air bubbles are a common problem in mixed, high

viscosity fluids. Improper thawing can introduce air to the fluid

supply, which results in intermittent shots. De-gas the fluid if

possible in a vacuum chamber.

Fluid Pressure

Dispense

Volume

Verify that the fluid supply has been set up correctly and that

fluid is free to flow to the jet chamber. Verify the pressure setting

is correct. Insufficient fluid pressure results in small shot

volumes or no shots. Too much fluid pressure leads to larger

shot volumes.

Valve Pressure

Dispense

Volume

Needle assembly travel is affected by valve pressure. Lower

valve pressure increases jet reaction time. In high duty-cycle

applications, sufficient valve pressure is required to meet

performance specifications.

Jet On/Off

Time

Dispense

Volume

The time the solenoid control signal is held on is termed “On

Time”. The time between “On” signals is termed “Off Time”.

On/off times that are too small will not allow the needle

assembly to fully open or fully close. On times set too large may

cause excess fluid to flow through the jet.

Dispense Gap Dispense Quality

A jet with the dispense gap set too low will “plow” through the

dispensed fluid and accumulate fluid on the nozzle tip. Dispense

gaps set too high will result in poor shot shape with a higher

frequency of dispense “satellites.”

SC-450 PreciseCoat Conformal Coating Jet Troubleshooting

Table 6-3 SC-450 Troubleshooting - Component Based

Component Quality Troubleshooting Questions

Nozzle

Size and

cleanliness

Is it the correct size? Was it cleaned completely? Does a new nozzle

have the same behavior?

Stroke

Adjustment

position

Was the stroke adjustment assembly removed? Was the stroke

adjustment set following the procedure? Is the needle assembly worn

or damaged?

Fluid Seal

Condition

and

Orientation

Is the seal worn or damaged? If being reused, was it cleaned

completely? Was the seal removed/installed using the seal tool

(Item 23)? Was it installed in the correct orientation?

Solenoid Operation

Are the electrical connections good - both at the bulkhead and in the

junction box? Is a minimum of 80 psi air being supplied all the way to

the solenoid inlet? Is the solenoid armature actuating (faint ticking)?

Can the solenoid open using the manual override? Is air exiting the

solenoid when operated?

Needle

Assembly

Condition

Is the needle assembly worn or damaged? Check the tip, fluid seal

location and the piston seal. Does the needle assembly move freely

in the jet body with the stroke adjustment assembly removed?

6.4 Input/Output Connection

7-PIN Female Circular Plastic Connector

Table 6-4 Pin Connector Identification

Pin Num Signal Name

1 +24VDC

2 SOLENOID (Sinking)

3 NOT USED (Sinking)

4 HTR PWR (+)

5 HTR PWR (-)

6 HTR RTD (+)

7 HTR RTD (-)