[SRD-Series] [CDM-Series] [ECS-Series] [HT-Series] [On-The-Fly Degassers] [Batch Degassing Tanks] [Curative Melters] [Urethane Casting] [Resin Transfer Molding] [Vacuum Potting & Encapsulating] [Vacuum Chambers]
SRD-Series Servomotor-Controlled,
Continuous Rotary Gear Pump Systems
Digitally accurate and fully programmable, SRD-Series systems utilize state-of-the-art
PLCs and servomotor-control for the rotary gear metering pumps. Optionally, coriolis
mass flowmeters are included for superior, closed-loop feedback ratio control. If needed,
you can easily select preset pour recipes for each of your parts by name or number at
the LCD or PC-based operator-interface touchscreen. You set digital presets for your
process control recipes, including ratio, shot-size, output rate, temperatures, vacuum
and mixer-speed, at the touchscreen interface. And the interface is menu-driven
for easy operation.
SRD systems meter, mix and dispense unfilled cast urethane elastomers, epoxies and
vinyl esters, among other flowable formulations.
Each of the positive-displacement rotary gear pumps on the SRD-Series system is of the
highest quality available and each is driven with an independent, digitally-controlled
servomotor drive. The rotary pumps handle cast urethanes, epoxies, polyesters and cast
nylons. Open-casting, VARTM (Vacuum-Assisted RTM) and closed-mold RTM resin
injection applications are also handled. Metering pump sizes are selected to match your
ratio and output requirements. Accurate ratio settings are made by entering your required
ratio at the LCD operator-interface. Typically, presets are also entered for shot-size, output-
rate and mixer speed. You can save those presets to the PLC as process recipes for later
use or you can enter and run each set of presets without saving them. Hundreds of recipes
can be saved.
When the footswitch is depressed, the the servomotors turn the rotary pumps, displacing
on-ratio streams of A and B component materials to the static (motionless) or dynamic (motor-
driven) mixer. Various systems provide outputs from 1 to 50 lbs/min. Ratios can range from
1:1 to 1:200. Two, three and four-component systems are standard and automatic color-
component metering with one or more color pumps is standard.
Constant positive material feed pressure from the degassing tanks feeds material to both pumps.
This positive air-free-material pressure from the tanks is created by nitrogen over-pressure in
batch vacuum tanks or by mechanical feed pumps on constant-vacuum thin-film degassers. These
mechanical rotary (or piston-type) feed pumps are submerged in the material or they are mounted
below the degassing vessel’s center bottom outlet for easier and cleaner access to the pumps.
Continuous recirculation is optionally provided at the mixer to keep the material in constant
motion; continuously diverting the independent on-ratio streams of material back to their
respective material supply vessels whenever the machine is not in pouring mode. The automatic
component injectors (2-way and 3-way valves) are located at the mixer and convenient ratio-
taking ports (for manually checking ratio) are provided. See our optional Mass Flowmeters for
automatic ratio monitoring and ratio correction, described below.
All heated compartments for the pumps and the mixer are made of removable slide-out panels
for easy access to all system components. Heaters are ceramic-enclosed infrared type, which
allow the system to be more easily modified at a later date to include third and fourth components
or to simply switch to different rotary pump sizes.
SolidWorks 3D advanced assembly modeling software is used to design all of our metering, mixing
and dispensing systems, including these SRD-Series systems.
More Information – See Overview and items listed below.
Rotary Gear Metering Pumps
Get precise, pulse-less, repeatable flow. These positive displacement rotary gear pumps include just three moving parts. This means less mmaintenance and more high-quality mixed material output. Various pump sizes, for example, 1.2 cc’s/rev to 200 cc’s/rev and larger, match any ratio and output requirement.
Servomotor Drives
Eliminate mechanically connected gear pumps, backlash and the need to manually change gears in order to change ratio. Digital servomotor-control offers much-improved controlled-rotation accuracy over variable-speed DC and stepper-motor-driven metering systems especially on initial ramp-up and at the end of the pour, where linear-ratio streams must maintain extreme accuracy.
Programmable Logic Controller (PLC)
The process control instructions and presets you enter at the LCD operator-interface are stored in the PLC (or optional Flat Panel PC Touchscreen.) When a pour is initiated, that part’s recipe instructions are passed on to the servomotor amplifiers, which precisely control rotational movement of the servomotor drives. Ratio, shot-size, output-rate, mixer-speed, pot-life alarm time and other variables for each part are controlled via saved recipes in the PLC or PC.
Coriolis Mass Flowmeters
The rotary metering pumps included with our SRD-Series systems provide extreme accuracy and long service-life. The independent servomotors are electronically (i.e., digitally) linked and this insures extremely close pump rotation and speed control. Truly precise ratio control, however, needs to rely and respond to continuous and near perfect measurement of the actual flow from each metering pump to the mixer. Our optional mass flowmeters, installed at each metering pump, provide the very best available, continuous, closed-loop feedback, ratio correction and control. With mass flowmeters, actual mass flows to the mixer are compared to the desired preset ratio. This way, the difference is corrected by incrementally increasing and decreasing the pump speed literally hundreds of times per second. Where do pump output and ratio errors come from? Long-term internal wear on the pumps, varying internal backpressures, notably from mixed-material unavoidably curing in the mixer output line and from factory-built clearances along each side of the pump’s gears. Continuous ratio verification is displayed at the operator interface and setpoints are easily entered for ratio deviation alarms and automatic system shut-down.