Nested Base Output - Nested Base Router Workflow and Productivity

Advice on organizing the loading, cutting, offloading, and labeling process to maximize the number of sheets processed in a day. February 2, 2011

We recently commissioned a nested based router and are averaging 8.34 minutes per pattern. This appears to be acceptable since we are machining all of our drawer parts in the mix. However, at the end of the day we are only processing 30 panels average. We have hired a water spider to move material and waste in hopes of improving the output but this has resulted in only sight improvements in the output. I do believe there are both valid reasons (programming errors, material handling) for this. Of those of you using routers, what are your average sheets per nine hour shift? Please feel free to offer any additional input, thoughts or suggestions.

Forum Responses
(CNC Forum)
From contributor L:
100 4X8 sheets/eight hour shift on parts with minimal machining meaning no adj. shelf holes, no holes for dowels, etc.

60 4X8 sheets/eight hours shift on parts with excessive machining. We have auto material handling KOMO512. In times like these we just wish we had the work to run it eight hours per day!

From contributor M:
What is a water spider? Seven to twelve minutes per sheet cut is pretty standard for case parts drilled and rabbeted either for confirm at or blind dado, all ops done and ready to band then assemble. You can always increase speed some, but for now, I think this is not the place to concentrate on. The place where most people get hung up is after a sheet is finished running.

I have seen a lot of shops just let the parts sit on the router bed with the router idle while they label all of the parts then pick each one up and put it on a cart. Then they blow down the table, load the next sheet and call the next program. It all takes more time for some than running the sheet.

Now the fact is, as that painful as it is to watch, that this is really just fine in an awful lot of shops. Demand time for the CNC is often less than 20 percent, and frankly it is only a higher volume shop that runs its machine even 50 percent of the time. I average 35 percent actual run time averaged over a 40 hour week in a commercial shop with ten guys on the floor, do all of the programming and rarely break a serious sweat. Now it seems that you want to get more than 30 sheets a day, and that is very reasonable on your part, whether you need to or not. I rarely have the need, but when I do 50 sheets a day is not a huge struggle, and as Luke says, 100 is difficult but possible, with compromises.

I have gotten my Spindle Off time between sheets down to under one minute with no fancy equipment, no auto loader and no scissor lift. I have made a push stick that slides along the edge of my spoilboard. I push the parts to an off feed table at the end of my machine. I drop the push stick where it stops, blow down the table and slide the next sheet off a pair of heavy duty saw horses in front of the machine. The next program has already been called while the last sheet was running. Hit cycle start. During the 7 to 12 minutes the sheet runs I label the pieces on the off feed table, end bore the parts that require it (we use confirmat, but doweling is all the same) and stack them on a cart. I normally have a minute or more left over, unless there is a lot of end boring or a sheet with nothing but a ton of drawer parts. At cycle stop I drag the push stick back to the start, it drops onto the top of a pop up pin and slide the parts away again.

Key points to consider:
Off feed arrangement and push stick design (or a removable spoilboard, but that takes longer).
Program call. It should be done while last sheet is running if possible.
Loading of next sheet material on feed.
Location of boring machine or bander or both to create a nested cell.
Cart design and material flow through your nested cell.
Dust control. How well does your machine pick up dust and where will you blow the dust that is left.

It is all not very strenuous, but you do have to pay attention. You need your programs to all run well. That will just come with experience. Being into this for a short time you should expect not only programming errors, but also a learning curve in machining strategy and nesting strategy. 30 sheets a day when just getting started is good, you will be up to 50 or 60 in a few months.

From contributor Y:
I nest from Cabinet Vision and it appears very efficient (I have nothing to compare too) I use blind dado construction with line boring for shelves. Router has tool changer and a drill block. Over the course of an average cabinet job we average about six minutes a sheet cut time. It is easy to average six sheets per hour unloading, cleaning table and reloading new sheet. Our router does not require each new program to be loaded by the operator so that saves time. One thing to note is if you plan to cut 60 sheets per shift you will need to allow for time to change the bits at the start or end of the day.

From the original questioner:
A water-spider is basically a person whose position is to keep the ball rolling. This person, in our shop, will stage panels to be cut or machined, oriented in a way that provides the most benefit to the operator. He will sort and run parts, empty waste, etc.

From contributor L:
I do 40-60 sheets per day nested on a 5x10 moving table - running all commercial work. I have an older machine without any load/unload help. If the nest has a lot of small parts that have to be onion skinned it takes too long. Handling is two sorted stacks on conveyors after routing. Some labels are put on while the machine is still running since the moving table can be safely away from the router motor. Dowel or confirmat construction with line bore, back groove and all hardware pilot drilling. Next stop - bander. If there are a lot of simple rectangular parts, shelves, they are sent to the panel saw instead of the router.