Watch this comprehensive tour of the GP-80 benchtop meter, mix system for dispensing pourable, 2-part materials. The GP-80 is comprised of a number of sections: feed tanks, metering section, power console with flow control, heat zones, and the dispense gun, which in this case is hand-held pistol grip with static mixer attached. The system shown has seven different heat zones. The GP-80 is used for unfilled epoxies and unfilled 2-part urethanes. Learn more in the video below.

In this video, we show how to use a robot to dispense into connectors. The cabling with the connectors is deposited in a nest—the one shown holds four connectors at a time—and the nest is placed on the dispensing robot. A grease cartridge is set in a pressurized container. The grease flows down through hosing to a spool valve, which is precisely controlled by the robot to do the dispensing via the selected program. The robot moves into position and dispenses material into the connector.

With two nests, the robot can take care of one batch of connectors while the operator prepares the next batch. To load a nest, simply move the connector into place, slide down, and put it in.

Ashby Cross 3800 Meter, Mix and Dispense System

Designed for Highly Filled, Abrasive Materials

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The Ashby Cross 3800 Single Acting meter, mix System’s design is based on our 2500 series meter mix system design.

It is cylinder and piston metering which provides excellent ratio performance (within 1% by volume) and repeatability. In-line metering ensures both metering pistons move simultaneously which eliminates the phasing seen in parallel configurations.

 

When coupled together on a common shaft the metering pistons effectively become a single unit, that is, if the A piston moves the B piston moves an equal amount. The volume ratio is achieved by matching the two cylinder’s relative volumes to the mix volume ratio of the adhesive.

The major difference between the 3800 system and the 2500 system is the volume of the metering cylinders.

The 3800 system is designed to produce just over twice the volume of material per stroke than the 2500 series. When processing materials with abrasive filler such as silica, this difference extends the useful life of the piston and cylinder by a factor of two. Hardened, chrome plated cylinders are designed for high abrasive processing.

3800 Series metering cylinders are designed for longer life.

10-gallon stainless steel pressure/vacuum tanks with agitators

Hi/Low level sensors and heat.

The 3800 machine can be fed from totes or 55-gallon drums – generally the material, due to high filler content and relatively high viscosity, needs to be prepared before entering the metering system. Preparation is generally done by inserting day tanks between the bulk feed supply and the metering. These tanks can be used to agitate, heat, and or degas the material. Agitation is almost always necessary. Tank size is usually determined by material use.

Tanks may be designed to automatically fill from bulk supply or can be manually filled. Hi/Low level sensing with alarms assist the operator during the refill cycle.

For high viscosity materials tank heating is employed to reduce the viscosity which provides better machine performance, better mixing, and faster part filling.

Heating is done with the use of an electric resistance coil located outside the belly of the tank. The coil is encapsulated in high-performance thermal compound and a thermocouple is attached to the tank bottom.

The thermocouple feeds a proportional controller that regulates the current to the heating element, reducing as the temperature rises to prevent overheating. This heating method is extremely effective, reliable and repeatable.

Vacuum degas options remove air from the tanks which is essential in wide ratio material applications. Air within the material is a major contributor to off-ratio problems.

On-board vacuum pumps degas the material in the day tanks

Flow control is achieved with 4-way rotary valve not ball check valves. 4-way valves direct the incoming flow into the metering cylinder where the ratio is established. Once full, the valves rotate 90 degrees, shutting off the incoming flow and connecting the cylinders to the mix/dispense valve.

How it works

 

The Resin and Catalyst cylinders have a respective volume matching the volume mix ratio of the material to be processed. For instance, if the material has a 2:1 mix ratio (Resin:Catalyst) then the catalyst cylinder will have a volume equal to ½ the volume of the resin cylinder.

In the fill operation, air pressure in the drive cylinder is removed. Each 3-way rotary valve (driven by a common actuator) rotates to the recharge (fill) cycle. Tank pressure or transfer pumps drive the material into the metering cylinders where the specific volume ratio is determined.

Once the cylinders are full the 3-way rotary valves rotate 90 degrees isolating the feed supply and connecting the metering cylinders to the mix/dispense valve. The Drive Cylinder is actuated and drives proportioned material to the dispense point.

Sealing Advantages

Processing High Purity Urethanes

High purity urethanes formulated for applications such as cable over-molding, cable connectors, cable splicing, electrical potting, and others require highly pure forms of urethanes to perform adequately.

From a meter, mix perspective the process equipment requires rethinking the standard design such that the integrity of the material is not degraded. Process variables such as thermal management, vacuum, materials of construction and other considerations will change the approach to the design.
With many unfilled, high-purity urethanes an excellent method of processing is the gear pump. It is simple, accurate, reliable, versatile and easy to maintain. It provides metering accuracies in excess of those specified by the adhesive manufacturer. Gear metering pumps are used in all areas of chemical processing including flow control and metering, and dosing.

By combining two precision gear meters, very accurate and repeatable ratio tolerances are achieved, typically within one percent by volume. The metering pumps form the heart of the system.
There are three basic functions in the meter, mix system; the prep tanks, the metering, and the dispense section. Each function prepares the material for the next operation.
Feed or prep tanks can provide heating, agitation, and vacuum degas which prepares the material for the metering section. The metering section then establishes the ratio and flow rate or shot size followed by the dispense section.

FEED SYSTEM
With the high-purity urethane, heating and vacuum degassing are necessary to prevent moisture contamination and crystal formation. Both of which will cause degradation of the urethane. Heating in the Ashby Cross system is done with electric resistance coils imbedded in thermal transfer compound located outside the bottom of the tank. A thermocouple senses temperature and feeds a proportional controller. This method is highly reliable, accurate and eliminates temperature overrun. Typically a local analog probe with display is mounted through the tank wall providing actual material temperature.

Top mounted agitators move material gradually within the tank during degas and heating to provide uniform degas and temperature. Vacuum pumps can be dedicated and located on-board to provide the necessary vacuum service. In some instances nitrogen is used in place of air to ensure moisture-free environment.
On-board vacuum pumps provide a dedicated
Degas source to the tanks

Metering
This is the section of the system that proportions the material in the specified volume ratio. In this case, two gear pumps, one for each side, will receive prepped material from the Feed System. Gear pumps are designed to produce a specific output per revolution. For example, combining pumps with different output such as 10cc/revolution and 5cc/revolution the system will produce an overall ratio of 100:50 by volume. To achieve other ratios, for instance 100:33, a combination of pump sizing and different relational speeds will produce the result.
With highly sensitive urethanes there is a need to maintain a uniform elevated temperature to prevent solids from developing. Therefore gear pumps are individually heated and controlled to maintain material integrity.
Heated gear pumps
The design includes wet cup reservoirs which surround the input shaft packings and seals. These reservoirs help maintain seal integrity and prevent material from leaking into the shafts area. By lubricating the shaft areas material leakage is prevented.
One of the major benefits of gear pump metering is the simplicity of the operation. Very few moving parts, self-bleeding, accurate metering, and infrequent maintenance combine to form a reliable simple system.

Dispense

From the metering section material flows through the dispense hoses to the mix/dispense valve. Here the materials are combined in the static mixer. The mix dispense valve can be static or dynamic depending on the nature of the adhesive and the mixing required.

The NPH-5000 valve features a snuff-back design, adjustable packings and drip-free operation. The valve makes use of the standard bell-mouth static mixer.
The DYNA-STAT® 6000 valve is available with pneumatic motor drive or electric motor drive. The drive selected will depend on the application. Electric motor drive has digital control with speed feedback console for repeatable and adjustable speed control. The air motor drive uses a pneumatic motor to drive the disposable mix elements.

– Ashby Cross Company

The DXBG table-top adhesive dispenser is a cylinder and piston metering device using gravity feed tanks located just above the metering section, a convenient and space saving method of material storage.  The metering section is designed to produce a specific volume ratio each time the cylinders refill. Once the metering chambers are full, two pistons drive the adhesive out through two ports directly into two corresponding ports in the plastic, disposable mixer where blending of the components takes place.

 

The wetted components are available in various plastics or 316 stainless steel which makes the unit ideal for most adhesive, including acrylics.

The control switch has two positions, continuous and shot. In the continuous position a constant stream of adhesive is produced, in shot mode, each time the foot pedal is depressed a shot is dispensed. An adjustable rod positioned within the unit can be used to provide accurate repeatable shots sizes.

 

The entire unit is mounted on a pedestal with adjustable height to accommodate different products.

 

Standard ratios include 1:1, 1.5:1, 2:1, 4:1, and 10:1. A much wider range is available; please consult with an Ashby Cross sales representative.

Depending on how the system is configured, max shot is approximately 85 cc and the smallest shot is approximately 1 cc.

The DXBG is an economical, reliable, and cost effective method of dispensing tw0-part adhesives in any production environment.

 

 

 

 

 

Please contact Ashby Cross at 978-463-0202 with any questions.