Question
I am the production/project manager of a 20 man custom shop in western North Carolina. I have been trying to implement some lean practices in our day to day operation. I'm looking for some good ideas for raised panel door production. I am finding that we can't get away from working in large batches, because of gluing up panels and wide belt sanding.
Forum Responses
(Cabinetmaking Forum)
From contributor T:
We recently reconfigured our door making cell in a way that it could be staffed by one person or could accommodate up to five people. Three of these positions have been simplified to where they could be staffed by the amount of training day labor would require.
The way to start is to list all distinct processes and time them. The goal is to have each process take the same amount of time. In some cases this will involve having more than one person on a station. To make this possible, the station has to be designed in a way that accommodates more than one person (think Lazy Susan, etc.).
Understand balance for staff sizes of 1-2-3 or 4. Just like soccer is played differently if you have three people on a team, the strategy will change if you have 6 or 9. You want your door department to be able to fluidly move from 1 to 4 people as demand requires or resources are available.
Not sure why batch size is a consideration at the widebelt sander or when panels are being glued up. I can understand batching for grain match or material yield, but after the material has been allocated, the batch size can certainly ebb and flow for all subsequent operations.
Because running one door through the machine, resetting it, and running the other side is not very efficient when you have 100 doors to sand.
You can't get a door into the finishing booth until it's been widebelt sanded. You can't widebelt sand it until the panel has been glued into a frame. The last operation is the bottleneck. You want to feed some work to the last operation as soon as you can in the work cycle.
And that statement is a thing of beauty. It is a part of my DNA the second I walk onto the floor, so I would have to agree without reservation. But it still makes sense for us to batch through the wide-belt, panel shapers, moulders, and edgers, things that still, in spite of our best efforts, have a distinct and costly setup.
The guys in the door department still cannot build their second door until they build their first one and they need a raised panel to build their first one.
If your organization has enough work to constantly staff all stations, then maybe efficiency at any particular station is paramount. Usually this is not the case. Your shop may be different.
To make the different processes match in time duration seems like a real challenge, especially with varying skill levels of different operators, but this scares me just a little: "Three of these positions have been simplified to where they could be staffed by the amount of training day labor would require."
What operations have you simplified so much that you can put a day laborer there and still get a consistently quality product?
We can move from Ovolo profile to Shaker profile in under 3 minutes without running any test pieces to see if the male/female patterns align. We do this by adding an adjustment shim to the copesled and stick shaper bed. Like contributor L, we also use a positive fixture to position the powerfeeder height when we make the change over.
If you think about it, marrying up cope to stick patterns is probably one of the most critical alignments you will ever do in your shop. Replicating crown molding can be a little bit tricky but the rubber meets the road when you can actually compare male to female and a misalignment will cause the door to twist.
This change over used to take our most experienced guy 45 minutes and about 10LF of scrap material to dial in. Moving from 45 minutes of high dollar labor to 5 minutes of anybody-can-do-it labor is a pretty big testimony for the reward from focusing on setup reduction.
Solving the problem with big batches just means you need more carts and more aisle space to navigate the carts. More work in process just equals more management.
Once those issues have been addressed think about:
- Does my stock replenishment methodology help reduce batch size?
- What metrics make you think your batch size is too large? So, for a given batch size determine the cost at each station as well as process cost (storage, movement, damaged or lost parts) for that batch size. Include the production station as well as its input and output buffers as one unit.
- As you make changes be sure to include the appropriate stakeholders in planning and design phases as early as possible.
- Look into change management techniques to help you implement the changes you want to make without negatively effecting the morale of your fellow cabinetmakers.
- Be sure to think about the system as well as the individual parts when you make changes.
Try this experiment: Take a flashlight and aim it directly at a door (90º from face of door) and see what the scratch pattern looks like. Take that same light and rake it across the face of door (i.e., flashlight is parallel with plane of door). In the second approach all of your scratches will become profoundly visible. In fact you will see that much of what you thought was sanded was still quite coarse.
This is a trick that photographers use to accentuate crevices and produce shadows. The models who appear to have perfect skin were photographed under a light source more like your overhead lights, big and diffuse.
If you configure your sanding station like a pocket screw face frame easel, it will be easier to see the scratch pattern. If the easel is configured like this and you use more than one grit of finish sandpaper, then operator 1 can do the 120 grit crossgrain, then slide the door down to the next guy with the 150 or 180.
The type of paper you use on the small sanders also makes a difference. Aluminum oxide is a real work horse but owing to the crystal structure of the stone tends to smash fiber. Silicon carbide crystals are sharp and tend to comb the fiber rather than smash it. Aluminum oxide at lower grits is probably adequate (and even desirable) for paint but you might want a different paper composition for your stain grade. If you smash rather than cut your wood fibers, your stain absorption will be uneven.
For some species of recalcitrant wood you might even want to consider misting the lumber face slightly and letting it dry. This will cause loose fibers to stand up when dry. They will be easier to cut off with sandpaper if they stand up from face of door.
You say that your problem bottlenecks from sanding forward. The other processes are the ones you have staff to draw from if you are deficit in sanding department. For this reason you should also experiment with leveling earlier processes. This effort will show you exactly where your surplus talent lives.
