Ink cartridges can be divided into two broad categories; those with the print head attached to the cartridges (e.g. HP, Lexmark, Dell) and those that are tanks of ink that fit into the print head which is fixed in the printer (Epson, Brother).

Those which are just tanks of ink can readily be copied as compatible cartridges and sold as cheaper alternatives to the OEM’s cartridges. Even the use of electronic chips can be circumvented. It is therefore not usually economically viable to recycle empty OEM cartridges of this type.

Those with the print head fixed to the cartridge cannot be copied because of patent rights on the print head and its electronics and so the only way to produce a cheaper alternative is to refill the OEM cartridges.

Some recyclers engage in the remanufacturing of cartridges involving disassembly, cleaning and replacement of parts. This is often necessary when cartridges are dried out having been out of the printer for an extended period. Other recyclers rely on refilling the cartridge soon after it has been used and any remaining ink has not had a chance to dry out. The McCue Vacumn refilling machine has been principally designed for use by those refilling cartridges although it could be used as part of a remanufacturing process.

The Structure of Ink Cartridges

The ink jet process of printing relies on a series of very fine nozzles being fed with ink and the ink being fired out of the nozzles by small heaters behind the nozzle plate. The heaters are stimulated by the electronic signal from the printer and create a bubble of steam that fires out the jet of ink.

As the ink is fired out air has to enter the cartridge to replace the used ink via vent holes in the top of the cartridge otherwise a vacuum would be established and prevent further ink from being fired out of the cartridge.

So these type of cartridges have a three part structure :-

• The print head with the nozzle plate and heaters connected to the contact plate on the side of the cartridge.
• A small chamber behind the nozzle plate which contains the ink to be heated and fired through the nozzles. This is separated from the main tank by a small filter.
• The main tank of ink containing the bulk of the ink.

Because the cartridge is open to the atmosphere at the top via the vent holes and at the bottom via the nozzles a mechanism has to found to stop the ink draining out under gravity. In recent times this has involved the use of foams. These are not your average sponges but are specially engineered to hold the ink back with just the right force (suction) to stop it from dripping out but not too strongly that the ink cannot be fired out through the nozzles.

Another attribute of the latest generation of printers is their ability to recognise that a cartridge has been used before. Some have expiry chips that are designed to blow once the cartridge becomes empty. This will not normally prevent the cartridge from being reused but users should be advised to ignore "ink out" warnings generated by the computer/printer and the lack of an ink level indicator.

The refilling process:

The McCue Vacumn machine has been designed to refill clean cartridges that have recently run out and that have a known history. This is the situation we expect to meet when dealing direct with the customer, whether a business or private user. The customer will have purchased a new cartridge, used it until the ink runs out and then requires a refill. In this case we know that the cartridge was working up until the point it ran out and that it is fresh and not dried out. Under these circumstances cartridges usually fill without undue problem and the effort required in preparation and refilling is minimised.

The machine fills the cartridge with an amount of ink prescribed depending on whether it is a low, standard or high capacity cartridge. To ensure there is no overfilling the cartridge is emptied of any residual ink by sucking it out through the nozzles. The emptying period is set to run long enough to empty a full cartridge so that it will allow for the worst case scenario of a cartridge or one of its colour chambers still being full.

Once the cartridge is empty, metered amounts of ink are injected automatically by peristaltic pumps which can be calibrated to deliver consistently accurate amounts of ink. This is carried out in a deep vacuum. This removes unwanted air in the cartridge and foam. Air in the wrong place in the cartridge is the most common cause of failures such as intermittent printing, print streaking, no printing, ink leaking, poor page yield, etc. The ink is delivered low down in the foam so that when the vacuum is released and air enters the cartridge through the vent holes the mass of ink is kept close to the print head. During this stage a short prime (suck on the nozzles) is applied to ensure a continuous ink link between the ink in the foam, the small chamber above the print head and into the nozzles.

The cartridge is now full and can be returned to the customer, the machine cleans its self either with a partial purge or a full purge, and is ready to fill another cartridge.