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Laser Printer Consumables
Most laser printers contain a number of "consumable" parts. Components that could be defined as consumable often make up more than half of the printer mechanism. One way of looking at it is that a laser printer isn't so much a machine in itself, as a shell into which a variety of exchangeable consumables and cartridges can be slotted. Printer makers put the bits that wear fastest in cartridges so a lot of repairs are simply matters of identifying and changing the right cartridge. A bit of knowledge about what is likely to go wrong can be helpful because sometimes there isn't much wrong and a valuable cartridge is discarded unnecessarily.
 | Toner is the main consumable. The whole purpose of a laser printer is to deposit small dots of toner on the paper. Printer manufacturers normally assume that 5% of the paper will be covered with toner - but of course a user can print anything between a blank white page and solid black. Solid black pages will use the most toner, but even an almost entirely white page may waste some because most printer cannot avoid some waste. Toner use is generally roughly proportional to page cover but continual printing will use less toner, partly because there will be fewer cleaning cycles per page printed. Colour printers have four sets of toners and users are substantially more inclined to print logos and photos so page cover tends to be much greater with a roughly proportional rise in costs. |
 | Waste toner is collected in a bottle. Almost all printers spoil a small fraction of the toner during their operation -too much adheres to the drum. To handle the waste they need a waste toner bottle. It might seem obvious that the printer should re-cycle waste toner but this is actually difficult to do. Waste is crushed by the scraper blade, oxidised in contact with air and mixed with dust and contaminants from the printer's operation. Re-using waste will give blotches in the print. |
 | Laser printers are based on a photoconductor, usually a drum. Most printers use up an "OPC kit" - an Organic Photo Conductor. OPC is made from a couple of layers and the top layer wears through. Although drums could last a long time in principle, they usually wear out quite quickly - somewhere between 5,000 and 50,000 pages depending on design. Silicon drums could last "forever" but they bring other problems. |
 | The developer is the mechanism that applies toner to the OPC kit so that the latent image picks up material. Developer wears out. Most older developer designs mix toner into iron filings then use magnetic rollers to present the mix to the OPC. The filings gradually break up, rust into oxide, and bleed out of the mechanism onto the paper. Resin based developers pick up contaminants and lose their "stickiness". |
 | The fuser fixes the toner to the paper - almost all fuser mechanisms are both hot and in contact with the paper so they will wear out. Some fusers use a very thin layer of oil to prevent molten toner under pressure sticking to the rollers. The oil is consumable. Despite oiling the rollers gradually accrue spent toner and paper dust. The heated toner roller is generally coated in teflon, and after some time this wears out, particularly where it is in contact with any thermal sensors. The high kaolin content of smooth British paper may be a cause of premature fuser-roller failure. |
User Puzzle.
A lot of early printers had about four components that were supposedly user changeable. A printer with lots of different consumables could present a bit of a puzzle to users. When something goes wrong what should they replace? A lot of older printers solved this to some extent by simply counting how many drum, developer and fuser print cycles had been used and then prompting for them to be changed - regardless of their actual condition. This doesn't work well for toner because of page-cover differences. The toner may be intended to last 5,000 pages but someone producing white on black pages will be lucky to make 500 pages!
Users often aren't very familiar with anything beyond toner. Adding toner happens quite often. Changing developers or drums often gave trouble.
The fuser has been a particular issue. Fusers last 150,000 pages or more so users aren't familiar with them. Fusers get hot so manufacturers don't make them into a cartridge, instead its an "engineer changeable consumable" - which means a call-out charge.
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Maintenance.
The main works of most laser printers are almost entirely consumable. Maintenance and repair can be simplified by the consumable nature of parts, fault finding is simply a matter of exchanging things until the fault goes. The problem is that the cost of consumables can be more than half of the cost of the printer. Because there is downward pressure on printer prices and resistance to pressure on consumable prices it can less expensive to just buy another printer -in the short term.
The consumable nature of printers can have some odd effects - for instance maintenance companies may offer very low prices for contract cover on hardware failure. Calls relating to consumables may be chargeable. Furthermore the maintenance technician might carry the consumables and change them, but charge the full retail price. The amount actually paid for cover could easily be far in excess of the contract price. What can actually happen is that a contract is actually a license to the maintainer to sell consumables.
The general direction of printer design is to use one or two smallish cartridges that the user will be familiar with and can change relatively easily. Coloured handles and tags help ensure the cartridge is lined up correctly for insertion.
Small cartridges can be cheap. People don't seem to get excited when they have to change a £35 cartridge but they get downright annoyed when they have to change a £120 cartridge. It doesn't seem to matter in the least that the £35 cartridge may only hold 3,000 pages worth of toner where the £120 cartridge might be good for 30,000 pages. Small cartridges may be bad value but they are usually a much better marketing proposition.
Cartridge numbers are cut by incorporating everything into one integrated cartridge. Each cartridge change is an opportunity for confusion and annoyance about expense. Older laser printers often had something like a 5,000 page toner pack, a 20,000 page drum, and a 100,000 page developer. People had a fit when they had to replace toner, developer and drum at the same time. Printer designers simply made the whole thing into one cartridge: toner, OPC, Waste bottle and developer into one disposable unit with a life of 5,000 pages. Integrated cartridges are potentially wasteful but simple for users.
Cartridges attempt to balance the consumption rates of their various components, but in practice the toner and waste bottle will generally be used well before the OPC drum and developer reach the end of their life. Economies of scale in manufacture can make cartridges potentially low-cost items.
Wasteful use of plastic and metal components could make cartridges environmentally unsatisfactory. The simplest action is just to refill the toner unit (and perhaps empty the waste bottle) and with little more trouble many cartridges will just go on working. However it isn't always that simple. Even if cartridges are discarded materials ought to be recovered and recycled - but then that means reversing the logistics chain that delivered them.
There is a general trend to small cartridges that are "affordable" - regardless of how long they last. This can actually mean that older printers are cheaper to run. Older consumables are often quite readily available both in new and refurbished forms.
People have got used to the idea that swapping their computer every few years is a good idea because a new machine will give much better performance. Printers don't improve quite so dramatically - ten year old laser printers often have performance that doesn't fall far short of today's machines - 600 dpi print has been a standard for a long time. If an older printer gives poor performance with pictures then an extra 64 MB of memory will usually improve things.
Newer printers do trend to quote higher print speeds - 20 page per minute upwards, rather than 10 page per minute and downward with older generation machines. Actually this can be a bit misleading as well. The speed increase can be a bit elusive in practice. It can be irritating to wait whilst a printer chugs through 5 copies of a 5 page report a couple of minutes before a meeting but it's not always clear that a new printer would be a dramatic improvement.
So before taking a PC upgrade as an opportunity to buy new printers it might be worth looking at the price per page.
Bulk Consumables.
Some photocopiers and high speed laser printers take a very different approach. Rather than a few cheap cartridges they supply toner as a big bottle to be poured in as needed and developer and drum as a long lasting components. Photocopiers often work this way because they are often placed on site on a per-page contract price, rather than sold outright or leased. Obviously the contract operator is keenly sensitive to the operating cost.
In kilo bottles toner powder is quite a cheap commodity. One problem seems to be that the photocopier usually has a guardian angel of some kind - a member of staff who takes a personal interest in it. The copier engineer will come out in a couple of days if it fails - but people don't want to wait that long so they take care of the machine.
Printers by contrast are spread all through the building and at the slightest problem people call out IT.
There is no inherent reason why printers can't do the same thing but generally things are moving the other way. Printers are cheap, consumables to put in them are cheap but don't last long.
All but one laser printer design has created some waste. Printers with separate toner, developer, drum and waste bottle can make the least waste because the life of each can be fully realised. If the developer and drum assemblies last their full natural life rather than being swapped out when the toner exhausts that ought to be better.
Obviously the environmental impact changes if cartridges can easily be refurbished and recyled. All the printer makers sponsor some kind of recycling scheme. All seem to be sponsoring their own proprietary recycling scheme based on big national depots.
No printer maker seems to have gone so far as to publish the full specifications for their consumables - or to make components readily available.
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© Graham Huskinson 2010
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