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An enormous number of medical
and non-medical products are assembled using
plastics joining solvents. Traditionally, the
majority of these assemblies have been made
by dipping the components into a small container
of solvent and then blotting the excess away.
This method although effective, presents a number
of problems:
- Operator
is exposed to high levels of solvent vapor.
- The wetting
of the component is inconsistent as the depth
of solvent in the container is constantly
varying.
- The operator
is less efficient due to the wasted motion
of blotting.
- There is
typically a substantial volume of solvent
wasted in the blotting operation.
- There is
a fire hazard presented by solvent in an open
container.
After years
of using the dip and blot method and struggling
with the few commercially available dispensers,
we designed the SD7200™ Solvent Dispenser.
In the three years since its' introduction,
the SD7200 has become the product of choice
for many of the world's largest medical device
manufacturers. Due to the value engineered design
it is also selected by much smaller firms as
well. The product is so versatile, it is used
by several companies to apply silicone lubricants
to components.
The Ventrex model SD7200™
Solvent Dispenser represents a break through
in solvent dispensing technology. From the ground
up, this dispenser has been engineered with
diverse medical bonding in mind. Designed for
the operator, the technician, the manufacturing/process
engineer and the safety manager, the model SD7200
is unsurpassed in performance, reliability and
safety.
PRINCIPLE
OF OPERATION
The model SD7200 consists of two primary
subsystems: A pump drive module and a fluid
delivery module.
The pump drive
module is 100% pneumatically operated to minimize
explosion hazards associated with solvent dispensing.
Plant line air is coupled to the dispenser with
a standard quick disconnect fitting. A dual
acting air cylinder is controlled by an air
bearing, pneumatically piloted control valve.
This bi-directional valve is speed controlled
by a precision integral regulator to allow repeatable
metering of solvent.
The fluid delivery module consists of a primary
reservoir, a positive displacement pump, a secondary
reservoir and a solvent applicator. Solvent
is transported from the primary reservoir to
the secondary reservoir by a fully submerged
piston pump. This pump is actuated by the pump
drive module described above. The solvent is
then gravity fed from the secondary reservoir
into the application area. A solvent film is
uniformly applied to the desired component by
transfer from non-clogging porous materials
contained in the applicator.
DESIGN
CRITERIA
The Ventrex model
SD7200 is designed and manufactured to provide
highly accurate uniform dispensing with a minimum
of effort and a maximum of operator safety.
The product will perform reliably on a wide
range of external diameters, internal diameters,
and both simultaneously.
PERFORMANCE
Accurate
Uniform Wetting: Uniform and
consistent wetting is a primary objective in
achieving reliable repeatable solvent bonds.
Using the integral regulator, the Ventrex
model SD7200 is adjustable over a broad range
of solvent delivery rates. The right
amount of solvent is applied to the desired
component without the need for part rotation.
As part diameters vary, solvent delivery can
be adjusted to match. The regulator is supplied
with an adjustment guard to prevent unauthorized
changes once the optimal setting is made. Uniform
wetting is assured by using porous application
materials in a size and shape specific to your
parts. Porous materials have been proven to
apply highly consistent films of solvent when
the surface is continually fed under slight
positive pressure.
I.D. and O.D.
Bonding, or Both Simultaneously:
Ventrex supplies applicators to apply solvent
on internal surfaces, external surfaces, or
both simultaneously. All applicators are
interchangeable making the SD7200 extremely
versatile. The ability to apply solvent to I.D.
and O.D. surfaces simultaneously saves the operator
time while facilitating a more consistent bond
than can be obtained from a two step application
process.
Anti-Capillary
Action: With traditional solvent
application methods, small inside diameter components
are prone to undesirable capillary filling.
When this happens, the operator must take extra
steps to remove the excess solvent. The removal
process not only subjects the operator to additional
vapors or solvent mist, but also increases solvent
consumption by as much as 80%. The Ventrex SD7200
can be regulated so that capillary action
is eliminated simply by adjusting the solvent
delivery rate with the integral precision regulator.
The use of porous application materials also
helps assure an optimal volume of solvent is
present at all times. The net effect is shortened
assembly time, reduced solvent usage and minimized
scrap.
Drip
Stop Applicators: The
unique design of the applicator prevents solvent
droplets from pooling on the end of the component
and then being inadvertently withdrawn into
the work area. This feature keeps the work
area clean, minimizes solvent waste, and controls
vapors.
SAFETY
Vapor Control:
The generation of potentially harmful vapors
is an undesirable side effect of solvent dispensing.
The Ventrex model SD7200 dispenser has been
specifically designed to minimize solvent vapor
exposure without the use of cumbersome and expensive
vapor removal systems. The pump shaft incorporates
a PTFE spring loaded seal to prevent solvent
in the primary reservoir from entering the pump
drive module. The fluid path is integrated into
the pump housing to eliminate tubing, connections,
and potential leaks. Finally, solvent inert
gaskets have been provided at all fluid interfaces,
leaving only the immediate application opening
in contact with the room atmosphere.
100%
Pneumatically Operated: Since
many common bonding solvents are flammable,
the Ventrex SD7200 has been engineered to use
only pneumatically driven power train components.
There are no electrical power requirements.
Air logic circuitry provides precise dispensing
volume control while minimizing the potential
for explosions.
Large
Stable Base: The SD7200 has
a low center of gravity to prevent accidental
tipping. This further protects the operator
from accidental solvent exposure and vapors.
Safe
Refilling: The SD7200 can be
easily and safely refilled at the work station.
The filler cap provides a positive seal and
yet is easy to open. The filler hole is level
with the top of the primary reservoir which
assures the solvent head height is never above
the pump drive module. A high quality sight
gauge is built into the reservoir to provide
continuous indication of the fill level. The
high volume primary reservoir minimizes the
frequency of refilling and resulting solvent
and vapor exposure.
CONVENIENCE
Non-clogging
Design: The porous materials
used in the applicator area are continuously
flushed by the gravity fed solvent. Unlike porous
materials fed by wicking action, clogging
is virtually eliminated. The unique
I.D. porous material self cleans each time a
component is inserted. Although the use of clean
solvents is recommended, a pump inlet screen
is provided to prevent possible contaminates
from entering the fluid path.
High
Capacity Primary Reservoir:
The Ventrex model SD7200 holds one liter of
solvent. This will typically allow uninterrupted
bonding for one week or more between refills.
This minimizes down time and increases throughput.
In addition, many solvents are supplied in one
liter bottles. By using the entire bottle, time
is saved in material transport and partially
filled bottles are eliminated from the production
floor.
Easy
Component Insertion: Applicators
are available with a variety of tapered lead-ins
to make locating components into the applicator
easier. This allows the operator to perform
multiple tasks simultaneously.
Rugged
and Stable: The size of the
model SD7200 provides a stable base thus preventing
it from sliding even if the operator aggressively
pushes a large component into the applicator.
This allows the dispenser to be located in a
variety of work areas without requiring special
mounting.
Quick
Applicator Exchanges: If a line
changeover is required the dispenser applicator
can be quickly exchanged. The applicators are
keyed to make alignment positive and easy.
Universal
Power Requirements: The SD7200
can be used wherever compressed air is available.
A simple change of the quick disconnect coupling
will allow operation anywhere around the
globe without the concern for voltage variations
associated with electrically powered dispensing
systems.
CONFIGURATIONS
Applicators
are custom made to your components. Each
Ventrex Model SD7200 comes with one applicator
of your choice. Applicators can also be
ordered with large tapered lead-ins to facilitate
easier component location. All configurations
are interchangeable.
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