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The Ashby Cross Company Blog

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.

MFS Mixer web

Outlet ports on the manifold mate with inlet ports on the disposable static mixer to eliminate cross contamination.

 

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.

DXBG copy

 

 

 

 

 

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

Vacuum Potting

Posted Jan 18, 2013 by

The Importance of Vacuum Degas in

Adhesive Dispensing Equipment

 

Ashby Cross often incorporates a vacuum degas system in their meter, mix equipment. Vacuum degas can include each side of the adhesive or just a single side.

 

There are several reasons degas is incorporated into the design.  They include material sensitivity to moisture or air, wide ratios such as 100:7, viscosity, and application.

On-Board Vacuum Pump is an Integral Part of the Design

On-Board Vacuum Pump is an Integral Part of the Design

 

Many urethane’s are moisture sensitive and should be vacuum degassed in the tanks to eliminate the chance of crystal formation. Typically when the equipment is off-line a vacuum is applied to the tank to remove air then the tank is locked up under vacuum.

 

In applications with wide mix ratios it is always important to degas the resin (usually filled and high in viscosity). The catalyst is generally unfilled and thin which usually does not require vacuum degas. High viscosity, filled resins will compress during processing. This always leads to phasing; a term used to describe how the two materials exit the mix valve, and enter the static mixer, at different times. Each time the valve opens the resin could flow before the catalyst or the opposite. At this point the mix is off ratio. As static mixing is generally plug flow, the off-ratio adhesive makes its way down the static mixer and into the part. When soft spots occur in the finished product it is likely due to phasing from the machine.

Vacuum tanks include necessary valves, gauges, regulators and an agitator

Vacuum tanks include necessary valves, gauges, regulators and an agitator

All vacuum degas systems include an agitator that slowly rotates within the tank exposing all the material to the surface vacuum. In addition, high viscosity adhesives usually require heating to reduce viscosity which enhances vacuum degas.

 

Certain applications such as clear-coating, high voltage potting, casting, and vacuum chamber potting require air-free dispensing to prevent failure or cosmetic blemishes in the product.

In these cases both sides of the adhesive are vacuum degassed.

 

In applications where adhesive is dispensed within a vacuum chamber vacuum degassing of the adhesive to a level lower vacuum level than the vacuum chamber will eliminate splattering of the adhesive during dispensing.

 

 

A high intensity discharge circuit being potted under vacuum.

A high intensity discharge circuit being potted under vacuum.

Including a PLC to in the design of an adhesive dispenser adds a great deal of flexibility and reduces the overall cost of the system. As with most PLCs, added functionality is built in. With the standard system an operator generally controls the operation of the unit.

The Ashby Cross adhesive systems with Intelligent Dispensing combines volumetric shot size control, gel timer, multiple shot sequences, menu selectable programs, and maintenance features.  As an example, if a product requires several shots of different sizes the sequence of shots may be entered into the unit through the HMI. Each time the machine is activated the precise shot size is dispensed each time.

 

PLC Based Adhesive Dispenser

PLC Based Adhesive Dispenser

Timely maintenance of any two-part adhesive dispensing system is essential to the proper operation of the system. The Ashby Cross units provide feedback to the operator such as the number of times the dispense valve has been actuated and the number of overall cycles the metering section has completed. In addition, maintenance set points can be entered which alert the operator when they are reached.

 

A linear encoder accurately measures the distance the pistons in the metering cylinders travel and relate that information to shot size. Each shot is highly repeatable. The operator only needs to depress the foot pedal.

 

In terms of cost, the built in features provided with the PLC save thousands of dollars over a similar equipped machine with the same features added as options.

 

The Ashby Cross adhesive dispensing systems are accurate, require minimum setup, have no phasing of the adhesives seen in many dispensers, and are simple to operate.

 

Combine Intelligent Dispensing with years of application experience and thousands of field proven systems and you have the seamless reliable dispensing package.

 

Ashby Cross has added a PLC based control system to one of our most popular dispense systems.  The 1125 Variable Ratio piston metering system is an excellent bench-top meter, mix for light to medium production potting. The cylinders and rotary valve used to control flow are hardened which provides many maintenance free cycles especially when using abrasive fillers.

The PLC adds a lot of flexibility to the process. Standard features include a pot life (anti-gel) timer with alarm,  machine controlled shot size via built in encoder, a five shot selectable menu, cycle counters for both  the dispense head and metering section, and cycle set points which provide data for preventative maintenance.

1125 Variable Ratio meter, mix with IDS

Automatic meter, mix system

In encoder mode, shot sizes range down to 0.3 cc with a +/- 1% repeatability. Maximum full charge volume is 160 cc at 1:1 ratio. The encoder also will sums the volume dispensed in each cycle and automatically refills the cylinders to avoid fractional shots.

Available options include heating and vacuum degassing, wide range of tanks with or without agitation, remote, hand-held snuff-back mix/dispense gun.

Ashby Cross has manufactured adhesive dispensing equipment for over 35  years. We welcome your dispensing questions – post them in the comments, use our Contact page, or call us at 978-463-0202

 

Potting thousands of small components with a 2-part silicone required an automated adhesive dispensing system integrated with a table-top robot.

The complexity of the dispensing required multiple passes at different flow rates then a final pass to level the adhesive.

The adhesive dispensing system used was a GP8O  gear metering system with vacuum degas capability in the reservoirs. The gear metering provided accurate ratio while the vacuum degas stripped air from the adhesive in the tanks.

When metering two adhesives at the design ratio it is important the two fluids react the same to the applied force. If compression occurs in the metering the ratio will not be accurate.

Programming of the robot is intuitive and done with a teach pendant. No actual code or dimensions are needed.

Almost any potting application can be automated with the wide range of tables available. Either gear metering or piston metering systems can be incorporated into a complete, automated dispensing system.

The versatility of the system permits the potting of different products.

 

Ashby Cross has manufactured adhesive dispensing equipment for over 35  years. We welcome your dispensing questions – post them in the comments, use our Contact page, or call us at 978-463-0202

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