Last year we purchased a CNC router with a plan to switch to nested manufacturing. Here is our experience with that project to date. When shopping for a router we were especially anxious to improve our through put in our shop. The process at that time was cut list from software to CNC beam saw, process parts through a CNC point to point, edge band and on to next tasks. Although we were batching kitchens by wood veneer species to a maximum of three kitchens per batch we realized that the first step in our process, the beam saw was most often cutting one sheet at a time (capable of cutting five sheets). This limited our through put to the maximum number of sheets that an operator could cut in one eight hour shift - approximately 67 sheets daily. The sales people for the CNC routers (regardless of brand) boasted that their machines would cut about 100 sheets daily. Our thoughts were that we could improve the through put and eliminate the point to point position.
Here is what really happened. The CNC router is possibly capable of cutting near 100 sheets daily under the following conditions. There can be no time allowed for spoil board maintenance, no tool changes because of dull cutters, one type of material being cut (stacked beside the machine) no labeling of parts and no sorting of parts for the next task. Our real world processes require that we cut varying veneer species, sometimes veneer is down white melamine is up (finished exterior cabinet), sometimes veneer is up melamine is down (finished interior cabinet).
Sometimes the material is veneer/veneer (cabinets finished inside and outside). Our cutting tools on our router provide clean cuts for approximately 100 sheets. We then have to change out the tool. We have bought extra collets and spindles to speed up this task (simple plug in new tool into tool changer) but the machine must still perform a tool length measurement program. Our most common material (white melamine is stacked by the machine and the operator has a panel lifter to assist in loading material). All other material is nearby but with five veneer species it must be retrieved from racking that holds all of our veneers. Normally we only have to dress our spoil boardsí once every seven working days. All parts are labeled to identify the job, the cabinet description, the part description and the part size in millimeters. Real through-put is 47 sheets daily.
Nested manufacturing produces irregular sizes cut offs. These initially increased our waste and caused handling and storage issues. We have most recently changed our programming in our cut lists so that only parts that require milling (shelf holes, hinge hole, drawer rail holes etc.) are cut on the CNC router. All parts that do not require any machining are produced on a second cut list that is processed at our beam saw. We first use all cut offs from the router to produce these parts so that waste is reduced to almost zero.
Since only the parts that require milling are going to the router we are cutting 45% of our total cabinet parts on the router and 65% of our total cabinet parts on the saw. This effectively changes our through put capacity to approximately where it was before. There is more that I could add if any specific questions come to mind. We are still looking for opportunities and wonder what other shops have experienced in the changeover to nested?
(Business and Management Forum)
From contributor R:
Is your router capable of pendulum processing or is a single sheet machine?
I would suggest three things to speed up the process. I don't know if you mentioned it, but do you have a push off device for the router? If you have to manually take parts off a machine and stack or sort them prior to starting the next sheet, you are wasting lots of time. My router pushes off the sheet onto a panel cart and vacuums the table at the same time, plus I set it up to leave the pop up pins down and the gantry out of the way so I can immediately load the next sheet. After I start the next sheet, I can label and edgeband the parts I just cut while the second sheet is being processed. There is very little down time for the router. The next would be to print labels at the machine so you could just stick them on the correct part. Most labels will have a bar code that has all necessary info for further processing, thereby eliminating the opportunity for a mistake.
Lastly, I would organize my software to optimize the sheets by cabinet. I set it up so that parts from no more than three cabinets can be on a single sheet. All parts from cabinet # 1 must be cut before any parts from cabinet #4 show up. This way you will be sending complete cabinets through the system. I am a one man shop with a sometime part time helper, and I can process about 40 sheets a day depending on how complicated the sheet layout is.