Maximizing CNC Utilization

06/06/2017


From original questioner:

We have a new CNC machine, and we are a high end custom residential shop. Lot's of euro, and some face frame. Question- how many guys are needed assembling boxes, finish assembly, etc. to keep a CNC machine running? Right now, with one to 2 guys assembling the machine gets used once a week, which is killing me! And I'm not seeing much in the way of return for the investment.

From contributor JM


You kind of answered your own question. If you are running the CNC on day per week, then 2 guys are busy for the week, you should need 10 guys assembling and 1 guy running the machine every day.

From contributor ri


JM is right, easy math. Most shops do those kind of numbers before buying the machine. Hopefully your orders will carry the machine, or else you need to hand out some business cards at some smaller shops to keep the CNC busy.

From contributor Bi


An interesting question how many hours did it take to make enough parts to keep two assemblers busy before the CNC.
How much remake was there? Was the quality the same?



From contributor Ad


We currently have 8 employees on our shop floor - had 10 and are trying to fill those 2 positions back, but 8 for now. Our cnc runs anywhere from 50 - 100% of the hours we are open each day of the week. Not all the employees are box assemblers obviously, but for us, 8 -10 total employees is what is need to keep everything running smooth. Make sure that you credit your staff for the work they accomplish while the CNC is running, as this is work that would be need to be done at a later time if you were still cutting by hand.

From contributor Sl


Our old pod and rail CNC was becoming unreliable. The controller would go out. The new software overwhelmed the machine, and it would 'ignore' some parts. Some aspects of pod and rail I liked, and I also liked Confirmat screws. I would say it was more accurate in some ways because we could compensate for thickness variation of panels better than the flat table we now have. But the new machine is 3 times faster processing on a per sheet basis.

From contributor Bi


3 times faster, You have to love that. It usually gets better the longer you have it.

Now your goal is to SELL SELL SELL!

From contributor La


Your CNC doesn't have to run full time or even close to pay. It is replacing a (much) slower method. What was that costing you in terms of labor, & equipment & OH &??
We are running an older KOMO. It takes about 6 minutes to cut a typical sheet plus 2-3 minutes of part moving/loading. We mostly cut larger sheets but a 4x8 will produce about 1.2 box cabinets. That's 60 or 70 boxes/day. One man can run the bore & insert, install the hardware and case clamp that many cases per day. (about 6 min/case.) The CNC operator may have enough time to run the bander if everything is setup right. That may be wishful thinking, but close. Lets say your operation is 12% inefficient, that's still 50+- cases per day from 2 guys. Buy out of drawers and doors (cheaper than you can make them!) Two kitchens/day.

From contributor st


We are a 6 man custom cabinet shop, we have now had our first cnc router for 5 weeks. Prior to purchase we did the numbers and figured we'd knock off about 20% labor per job. We have completed our setup of software and new shop layout and are just about done the first large cabinet job. We still have many area's that i know we can save more time on with minor procedure adjustments. Having completed this job with everything being new to us we already saved the 20% time on the job as we originally prediced.... i now fully expect to save 35% laboe once we have all the kinks worked out.... we will need to start handing out a lot of business cards soon because we're going to need more work.

From contributor Ch


Congrats on the new CNC. We love ours. It is consistently accurate, doesn't take days off usually (occasional maintenance is the exception), and has reduced the labor cost tremendously. It also does the work of multiple machines for some of our parts (table saw and line boring machine are two), and eliminates the need for many physical jigs and measuring tapes.

It is a great tool.

I have been following this conversation and one thing keeps coming to my mind.

I do not understand why so many folks see the need to keep a particular tool busy 40 hours a week, or even more. It is only one tool is the overall process. Why should the entire business be driven by keeping this one tool at maximum capacity?

For example, if we want to keep our automatic edgebander busy 8 hours a day, 5 days a week, we would have to have multiple busy CNC machines to keep feeding the edgebander. And, a larger area for raw materials. And, a larger area for WIP (Work In Progress), And, a larger area for assembly. And, a larger area for finished product. And, a larger installation staff. And, a larger sales staff to fill the production queue for using all of those raw materials. And a larger office staff to handle the paperwork. And, and, and...

I believe that the goal of a business is to be profitable. One measure of profitability is the size of the bottom line. Another is the ROI (Return On Investment) of the resources used (equipment, manpower, building, capital). Again, the goal is profitability, not revenue size.

Unless the short-term goal is to build a bigger business, as measured in revenue, or in number of boxes, or number of projects, or increased market share, then why would one set a goal of keeping one particular tool busy? If it leads to a more profitable bottom-line, either short-term or long-term as desired, then it could make sense. But, the goal is not to keep the machine busy. The goal is something else: Profit.

More revenue is absolutely no guarantee of increased profitability.

To increase everything else in the business just to keep the CNC busier... It just doesn't make sense to me.

By the way, our CNC machine is an older, slower machine. It is just as accurate as a new machine, just not as fast. But, we bought it outright. There are no payments. Depreciation, for the accountants, is long gone. Some basic maintenance is all that is required. So, if the CNC sits idle for a few days, or a week, it is ok. Oh, the space it occupies? Yup, our building is paid for as well. So, our overhead is really low. Our business goal is the best bottom line; not the busiest factory.

But, that's just the way I see it. YMMV.

Again, congrats on the new tool. It should serve you very well. Just don't let it make you its servant.

From contributor Ad


@ Charles,

Very well stated. I have felt this way for a long time. Most people feel that because a CNC is very expensive compared to other woodworking tools, that it must be used non-stop.

I understand that most companies are financing a machine such as this, and thus must increase cash flow to make that payment. Although this may be true, the CNC can't be expected increase cash flow all by itself simply because it is running.

The object is to lean up the entire manufacturing process in order to free up time to pursue those other areas that can generate more business, cash flow etc. A CNC is a great tool to aid in that process. When was the last time you heard someone complain because their chop saw, cordless drill or table saw didn't run non-stop every day? Could you imagine having 3 shapers running non-stop for 8 hours a day?

Where some shops fail, is that they don't utilize their employees talents to take advantage of the time savings. Most employees are expecting a paycheck with 40+ hours on it each week. If you save yourself 3 - 5 hours a job because the CNC is doing what an employee used to by hand, then you need to identify what additional tasks that person/persons can do to take advantage of that "extra" time.

Ever notice that when you are busy and everyone gets used to seeing 5 - 10 hours of O.T. on their check, then work that used to get done in a 40 hour week magically takes 45. It's a tough cycle to break.

From contributor ri


If you want to keep a narrow view of the CNC as just making parts that you assemble into final product, then yes it doesn't have to run that much. But why limit it to just working at the capacity of what can be assembled in your shop? Why not cut signs, make parts for other shops, etc....? Unless the operator is also an assembler, you are much better served keeping him on a running CNC.

From contributor Ad


Rich,

I see what you are saying, and those are ideas that would work, provided you had the man power to logistically handle those additional tasks. That's the beauty of the CNC, it frees up more time during the day to embark on other endeavors. Signs, outsourced parts, an additional set of kitchen cabinets, whatever as long as your staff can keep up.

From contributor Pa


I have had my router since 2000. I have an AXYZ with an 80" x 145" table. You can do a lot more than cut cabinet parts with a router. Check out our web site. Last year we did a curved stair, all the parts were cut with the router.

I could not live without my CNC router. In 2014, we duplicated some church pews that were 100 years old. We digitized an existing end cap, cut end caps to match, fun stuff.



From contributor St


I refer to it as "Feeding the Machine" it should be someone's focus to keep it fed as much as needed.

From contributor La


It appears that most everyone has agreed about the advantages of a router, How many have taken the next step of improving material handling and assembly? We started off with carts, lots of them eventually. There was a big saving in handling, and organization when we went to roller conveyors. The ideal might be neither carts of conveyors. Simply each part moves through the next operation with out stopping. Assembly can be sped up considerably by using a bore & insert machine, then case clamping. One of the beauties of the entire system is consistency. Parts are accurate, cases come out perfectly square and there is no backtracking, just a flow to the loading dock. I think it is possible to turn out twice the cabinets with the same labor force.

From contributor De


The CNC is only 1 tool in the production process. Cutting and machiningbparts might have been a major bottleneck before the CNC. Now with it, other items in the process have become the bottleneck. Running the CNC, 5 days a week will not fix the other bottlenecks only create a back up of parts in the shop. Doing parts that don't require additional work can be profitable, but only if they don't take away from other value added process.
We upgraded our cnc to an auto load/unload machine. It has taken is 3 months to fine tune our process so that we can take advantage of the 4-5 minutes a sheet that we save unloading the machine. We still have a long way to go in our process to make it as lean and efficient as we would like.

From contributor Pr


Although I am not a promoter of TOC (theory of constraints), I strongly feel that Goldratt's simple book "The Goal" in a novel form is very relevant to this context. This kind of situation is beautifully discussed in the book.

Improving shop throughput is much more important and meaningful than utilization of a specific resource, however expensive the resource is. Forget CNC utilization and focus on the market demand for your services and current bottlenecks in the system and improve them. In the near future, the expensive CNC machine may become bottleneck with very high utilization. Develop strategies to get more output from the shop.

From contributor La


We have continuously improved shop systems, the constraint has moved to the office. Harder to fix! All approval drawings go out fitting our system regardless of what their drawings showed. We will make to their specifications, for a price, as long as they are structurally sound. As usual, money talks, and they opt for our system 90% of the time.

From contributor De


The Goal is awesome on audio book. Ive listened to it on roadtrips with my teenagers in the car. I didnt think they were paying attention but aftet a lengthy stop, one of my daughters said "turn that book back on so we can hear if he saved the factory and his marriage "

From contributor Ad


Prasad & Derek are correct,

If you are hell bent on keeping a cnc machine running non-stop 40+ hours a week, then you better have the resources to keep up with it in every other facet of the manufacturing process. No good comes from having 5 jobs cut up and machined sitting on carts waiting to be assembled.

A cordless drill is faster at installing hinge plates than a screwdriver is. A table saw is faster and more accurate than a handsaw etc. Every improvement that you can make whether it is in your processes, machining, inventory control, all add up to time savings that can be used to generate more $

From contributor De


Let me add a mistake that we made early on with cnc. We did a time study on running it on cnc vs line bore and another secondary operation. The cnc was faster for the actual process, but we failed to take into account programming time. Yes we had a catalog of parts written parametricly, but we always had custom parts as well. After a while we looked at it and we were spending hours programming at the machine. The upgrade for us was Cabinet Vision that once set up programs every part automatically. I originally held off buying because I didn't want to spend $20k. In the long run I probably spent $50k on lost productivity.

If you can improve your other process and get things out the door, the next thing you will need to improve is your sales program, so you can have more work to feed into it.

From contributor Ja


The things stated here about TOC, especially in this context is the important point. Increase your sales as noted above, and make your system produce this increased demand of what you already know and sell, without increasing your investment (lean).