Shop Productivity With a New CNC

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It seems more efficient to go on cutting parts manually than to program the CNC... what's missing? October 5, 2004

We have an architectural woodworking shop and have most of the steps required to fabricate casework down to a science. Everybody has their specific duties and casework goes through the shop pretty efficiently. We recently acquired a CNC with all the bells and whistles. I'm wondering which duties should be assigned to the CNC to make things go faster. Unless there is an odd shape, the old fashion way of cutting things seems to be faster than programming the CNC. But this shouldn't be the way, right?

Forum Responses
(CNC Forum)
From contributor G:
Productivity can be sliced into many categories. If you have been running a shop proficiently, a CNC may not be an improvement to your system. If you have had quality issues in the past that may have made your productivity poor, then the CNC would be an asset. I think the sales guy who sold you the machine needs to spend some time with you to show you how your investment is going to pay off. I'm sure he did his best to show you all the benefits before the sale. Now I would think it's time for him to walk the walk.

From contributor T:
You must not have been the person who bought the CNC. If you were, you should have done an extensive analysis of potential productivity gains and already have a game plan before the machine was purchased.

In order to answer your question with any kind of valuable response, I would have to have much more information.

1. What products are you making?
2. What exactly are these processes that you have down to a science?
3. Anticipated volumes?

4. Labor content?
5. L&B costs for your company

I can say, however, that once you are past your learning curve and have competent willing programmers and operators, a well-run CNC will be more efficient and productive than a well-run manual system.

The biggest challenge will be changing your mindset. Your statements all revolve around what the fastest way is to do something. There are many more factors to consider than that simple comparison.

Here is what you want to strive for. You want to make as much product as you have sold with the highest quality, shortest lead time, and with the lowest overall cost.

I recommend that you find a part or family of parts that you could set up on the CNC where you could combine several manual operations, but keep up with sales. The key to holding your costs down is to have the operator doing secondary operations while the CNC is running. For example, set up a sanding booth or edgebander next to the CNC and have the operator do this operation during the cycle time.

Programming time can be reduced with practice, subprograms, parametrics, and automated routines, to where it is almost a non-event.

From contributor J:
You have received some very good information above. One thing I can't help but echo is that you bought the CNC knowing that it will somehow be to your advantage. The part about the mindset is real important. The people who work for you must accept that the CNC is not there to replace them, but to make their life easier. Any time I can cut 30-40 pieces of wood and know they are all identical, that is a good feeling. Can we do that on a band saw? I don't think so.

Believe me, in two years you will wonder how you got along without a CNC router, and you will also see that having two of them is even better! I hate to use the phrase "been there, done that", but we have three routers ,and I wish we had four.

Once you are past your learning curve and have competent willing programmers and operators, that is a major statement right there!

From contributor C:
We felt like you for a long time after we bought our CNC machine. Many of the benefits of speed accuracy and repeatability of the machine seemed to be cancelled out by the inefficiencies of non-value-added activities related to using the machine. For example, loading and unloading. It took us a long while to set this up so that the changeover took place fast and with ease. Dust collection - unless this is done 100%, it involves the operator having to clean the table between cycles and if he doesn't clean it properly, parts may move during cutting, which involves programming another part in another cycle. These activities take time and have a cost. There are many more issues. Thankfully, since we started to improve these, we have begun to get the value from our machine.

From contributor J:
Contributor C, how do you remove all of the dust? We have MDF and melamine dust packed into the kerfs from the force of the vacuum. The air nozzle is not effective in removing this dust. We have a 30 minute job each night cleaning dust from the back of the machine where we blow it off of the table.

From contributor C:
We got an ordinary industrial vacuum cleaner, 2 HP, and routed its two hoses right down to the spindle. We made up a nozzle about 60mm diameter that the bit passes through. It works well because there is high velocity suction right down at the bit. The nozzle has a spring-loaded hinge that is pushed out of the way when the machine changes a tool or parks a tool. When nesting, we always do it in two passes. It surprises me that the manufacturers who obviously put a lot into the technology of their machines seem not to have addressed this side of things fully.