SC_450 PreciseCoat Conformal Coating Jet_Rev_04.pdf - 第22页

SC-450 PreciseCoat C onformal C oating J et Operation 16 © 2024 Nordson Corporation 4.4.4 Solenoid Valve The solenoid valv e controls t he valve operat io n. When energized, it allows air into the pist on chamber to comp…

4 Operation

4.1 Overview

This SC-450 PreciseCoat Jet is designed for use on Nordson Select Coat Series Coating Systems. For

complete system operating procedures, refer to the applicable coating system Installation, Operations,

and Maintenance Manual. This section covers the following topics:

•

Theory of Operation

•

Application Settings

•

Control

Components

•

Hardware Selection

4.2 Safety First

Operation of the SC-450 PreciseCoat Jet involves air pressure, electrical power, mechanical devices, and

the use of hazardous materials, and sometimes may involve heat. It is essential that every person

servicing or operating the PreciseCoat Jet fully understands all hazards, risks, and safety precautions.

See Section 2 - Safety for additional information.

WARNING!

Allow only qualified personnel to perform the following tasks. Follow the safety

instructions in this document and all other related documentation.

4.3 Theory of Operation

The SC-450 PreciseCoat Jet is a normally closed, air-actuated, spring-return mechanism, which uses

momentum transfer principles to expel precise volumes of material. Pressurized air is regulated by a high-

speed solenoid to retract the needle assembly from the seat. Fluid, fed into the fluid chamber, flows over

the seat. When the air is exhausted, the needle travels rapidly to the closed position, displacing fluid

through the seat and nozzle in the form of a droplet. Multiple droplets fired in succession can be used to

form larger dispense volumes and lines when combined with the motion of a dispenser robot.

4.4 Control Components

The following features affect performance of the SC-450 and are typically adjusted to fit your application.

Contact Technical Support for additional information.

4.4.1 Dot and Line Parameters

In addition to the SC-450 hardware configuration and settings, valve timing and coating instructions are

set in the EasyCoat software program to control the frequency and speed of dots and lines dispensed.

For information on dispense parameters, refer to the EasyCoat User Guide or EasyCoat Help.

4.4.2 Fluid Pressure

Fluid pressure should be set so that fluid fills to the seat, but should not be influential in pushing the fluid

through the seat and nozzle. In general, fluid pressure should be set according to the viscosity of the fluid

dispensed, see Table 4-1.

4.4.3 Drive Needle and Fluid Needle

Drive needle and fluid needle geometries are typically the main factors controlling volume. Size is

determined based on fluid properties. Other parameters, like stroke and fluid pressure fine tune the

application. Sizes are listed in Item 20 through Item 22.

SC-450 PreciseCoat Conformal Coating Jet Operation

4.4.4 Solenoid Valve

The solenoid valve controls the valve operation. When energized, it allows air into the piston chamber to

compress a spring and thereby raise the needle assembly. When de-energized, the air is released and

the spring forces the piston down so that the needle tip contacts the seat. The valve ON/OFF times can

be adjusted in the EasyCoat software.

4.4.5 Stroke Adjustment

The stroke adjustment controls the travel distance of the needle or nozzle assembly. Turn

counterclockwise to increase needle or nozzle assembly travel, turn clockwise to decrease travel. Stroke

is directly proportional to closing velocity of the drive needle.

To set the stroke stop:

1. Tighten the stroke adjustment knob all the way down until stopped.

2. Back the stroke adjustment knob out to required setting.

4.4.6 Heater Temperature

Fluid temperature is used for process stability. Set the fluid temperature 5-10° above room temperature.

Adjusting the fluid temperature higher can be used to help dispense higher viscosity fluids.

Most conformal coating materials have solvents, even 100% solids have solvents.

WARNING!

Use caution when setting above 45ºC. Solvents will boil in the fluid chamber

causing internal failure.

4.5 Application Settings

Table 4-1 Sample Application Settings - Lines (Spacing Mode)

Initial Settings

Comments

Category

Settings

Unit

Fluid

Viscosity

600

1200

cps

Valve Pressure

80 (SL-940)

Main Air (SL-1040)

psi The parameter does not require adjustment.

Stroke

Adjustment

5 20 25 graduations

• If fluid is accumulating on needle tip, increase stroke.

• If fluid is atomizing (satellites), decrease stroke.

•

Use a large

stroke setting

for a

tighter volumetric repeatability

Fluid Pressure 5 30 60 psi

• Use higher fluid pressure for tighter volumetric repeatability.

Heater

Temperature

35 °C

• Set 5 - 10° above room temperature to be used for process

stability.

Valve Timing 3 On / 3 Off ms

• Minimum On/Off Time is 3/3 ms.

• Position based timing is recommended.

•

Zero Start and Stop Distances is recommended.

Dispense Height 2 mm

Adjust the height to lowest possible without part interference.

Lower heights are more repeatable and help prevent accumulation

during production.

Drive Needle

6.4

See Item 20.

Fluid Needle 150 um or 22 ga um See Items 21 and 22.

SC-450 PreciseCoat Conformal Coating Jet Operation

4.5.1 Fine Tuned Settings

For volumetric repeatability applications, the following parameters will help decrease repeatability.

Table 4-2 Volumetric Repeatability Factors

Parameter

Action

Shot Size Increase

Stroke

Decrease

Fluid

Pressure

Increase

On Time

Increase

For noise sensitive applications, the following parameters will help reduce audible noise levels.

Table 4-3 Audible Noise Factors

Parameter

Action

Drive

Needle

Q type Needles (

See

Item 20

)

Stroke Decrease

Drive Frequency 145Hz (3ms On/3.8 Off)

4.6 Hardware Selection

Hardware selection is based on multiple factors and the values are application dependent. These are

Asytmek starting points, contact Technical Support for additional information.

The SC-450 can be configured for two (2) different needle types, other needle types are not supported.

Utilize Table 4-4 to assist with the needle types.

Table 4-4 Needle Types

DL Type Needle Hubbed Nozzle

Precision Applications

Accessibility Applications

Higher Viscosity

Lower Viscosity

Small Dots and Lines

Larger Dots and Lines

1.5 - 3 mm Line Widths 2.5 - 3.5 mm Lines and Widths

6 mm

Component Clearance

12 mm

Component Clearance