Are you primarily nesting? How many sheets a day do you need to process?
Regarding nesting the newest advancements in nesting machines relates to the number of vacuum zones and the ability to focus more vacuum in the area the head is actively working. In the past 3 or 4 zones on a 5x12 table were considered sufficient with the concern being to zone off an area the size of the panel and not bleed through the unused area of the spoil board of the larger table when 4x8 sheets were being processed. Manufacturers are now moving towards 9 even up to 12 zones depending on the machine size and concentrating the vacuum in the active zone to prevent part movement. This also allows for faster cutting speeds and of course fewer part rejections. This was one of the technologies Nutek Machinery recently sought out to determine who we would partner with to sell and service in the U.S. market. There are a few manufacturers that are doing this, and it is worth your time to look them over.
When you consider the number of sheets you want to process in a day you will always want to look at the cycle time for loading and unloading a panel if you are considering a full line. If you want to process 10 sheets an hour and the cycle time to load and unload is 1 minute than you have 50 minutes left in the hour and 5 minutes per sheet of run time to reach your goal. One factor to consider in panel cycle time is the linear cutting speed of the machine. How many inches per minute can you cut? It goes beyond the speed the machine is rated to cut. You also have to look at the acceleration/deceleration time of the X and Y axis. If you are cutting at 1100 inches a minute but the acc/dec time is slow, you will burn up the tooling in the corners. A machine with a faster acc/dec will allow for faster linear cuts.
Providing spare parts for 25 years should be the norm. These are large investments, and it should be up to you to decide when your machine is ready for the graveyard, not the inability to get the proper support. But you should keep in mind technology changes quickly and planning to run a 20 year old CNC puts you at a competitive disadvantage. Regardless of the volume you want to run you are still investing labor hours into processing your parts and the longer it takes to do that the higher your costs are, compared to the guy that is doing it in half the time.
As a technician other key factors in my mind would be the size of the spindle and drill block and the brand of controller and servos used. Regarding the machine control and inverters, the brand matters as does whether they are off the shelf items or proprietary to the company selling the machine. There is nothing worse than finding the machine builders tag on an inverter or controller. If those items go out be prepared to pay ten times what the standard off the shelf unit would be for the same brand. The issue of proprietary parts was one of the primary concerns we considered when determining the European lines, we would import.
Member