Office copy machines are more powerful and capable than ever before, but this doesn't mean you should rely on them for every copy job in the office. There are some copy jobs that are better left to a professional printer or duplication service, and sending these jobs to a printer can help preserve the life of your machine, while also reducing downtime at the office. In the long run, it can even be cheaper to rely on a duplication service or printer. Note when that may be the case for print jobs in your office.
Finishing refers to what needs to be done after copies are produced, including stapling, binding, three-hole punching, or laminating. Your own copy machine may not offer all the finishing services you want, and having your staff manage this work by hand can be very time-consuming. It can also be more expensive to do work like laminating in-house than having it done by a duplication service, as a printer may give you a discount for bulk projects and high-volume finishing work.
Many office copiers offer colour copying, but remember that colour toner or ink cartridges are often very expensive. You may not need to worry about the cost of making the occasional colour copy, but for high volumes of copying, this can add up. To figure your cheapest option, note the retail cost of your colour toner or ink cartridges and their output or yield, and compare it with the volume of copies you need; you may see that it's actually more expensive to pay for the cartridges for your office machine than it is to send out that copy job.
Double-sided or glossy paper
Your copier is more likely to get jammed if paper needs to be flipped around or go through a secondary set of rollers in order to produce double-sided copies, or if the copies are on glossy paper that the rollers can't grip so easily. For high volume jobs, it can get very tedious and time-consuming to constantly remove paper jams and reset the copy job. This may also put more wear and tear on your machine as those rollers struggle to work.
For any type of special job that is more prone to causing jams, use a duplication service, as they are likely to have high-quality machines with heavy rollers that more easily grip glossy, thick, or other specialty papers. Those machines are also less likely to get paper jammed in the rollers when it's flipped for two-sided copying.