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Walk around any of the numerous stone trade shows and you will see at least a dozen companies selling CNC machines. It seems everyone is getting a CNC. There are many success stories and others have failed miserably. What can and can't a CNC do for you? This article will explore the pros and cons of CNCs and to help you decide if you are ready to purchase this technology.
What Is A CNC?
CNC stands for Computer Numeric Control. The movement of the machine is controlled by a programmed computer using a written language called a G code. Most of today's CNC machines have the G code prewritten in the software and knowledge of G code is not necessary. In simple terms a CNC is a computer-controlled robot.
Most people in the stone industry relate CNC with a CNC router; however, CNC technology can also control bridge saws, waterjets and laser etching machines to name a few. For the purposes of this article I will focus only on CNC routers.
What Can A CNC Do For Your Business?
When properly programmed, a CNC can produce a finished piece in less time than manual labor. Because the finished piece will match the template exactly, the quality of the finished product is consistent and, in many cases, better than manual labor.
Many CNCs will also calculate the total time to fabricate a certain job. This can be difficult to do with a manual operation. A CNC can also save time on slab layout and templating if you incorporate one of the many electronic templating systems.
A CNC can save on labor also because it does not need a day off or coffee breaks during the shift. It doesn't even need lunch, but keep in mind that a CNC is a machine and will at times break down and need repair and maintenance. Human error is not totally eliminated because a programmer must enter the information into the machine. However, there are many checks and simulations that can be performed so that errors are less frequent.
Can I Afford A CNC?
Before you can answer this question, you should first ask yourself if you have enough work to fully utilize a CNC. If you are only doing one kitchen a day, a CNC may not be for you. As a matter of fact, if you are only doing one or two kitchens a day, a CNC may cost you more.
CNC machines will vary from model to model and from manufacturer to manufacturer. The following example is based on one of these machines and information from the manufacturer. I have also modified some of these figures based on my personal experience with CNC operation and cost. Production rates and payback can be more or less.
Let's say you purchase a CNC for about $210,000 and decide to lease it. Your lease payment will be around $4,200 per month. If the machine works for eight hours a day, 21 days a month at a production rate of 14 linear ft. per hour, that translates to about 2,350 lineal ft. per month. Loading and unloading the machine, however, can take up 10 to 20 percent of the time, reducing the lineal ft. per month to about 1,900 lineal feet.
In addition to the machine cost you also need to calculate operator and tooling costs as well as power, water, etc. For the purposes of our calculations, let's assume that a set of tools for one profile cost $3,000. The life of these tools is approximately 2,500 lineal ft. This translates to a tooling cost of about $2,500 per month. CNC operator rates can vary considerably from state to state. I have seen rates as low as $16.00 per hour and as high as $40.00 per hour or more, plus 20 percent burden for benefits, etc. In addition, you must calculate the labor rate for loading and unloading the machine. This calculates to a range of approximately $3,300 to $8,000 spent on labor per month.
Now, let's total this all up. Your cost to operate the CNC for one month based on 1,900 lineal ft. will range from $10,000 to $15,000 per month. This does not include power and water consumption or the labor involved for computer time, etc. The cost will be higher than this calculation, but it can serve as a guide and a starting point to help you calculate your cost.
This will put a total lineal cost per foot in the range of about $5.30 to $8 or more. If you charge $20 per lineal ft., then you will generate about $37,000 per month.
What I don't know, however, is your overhead, labor rates, etc. This is something you need to sit down with your accountant to discuss and determine if a CNC is worth the investment. Also, keep in mind the setup cost as well as the learning curve. Don't expect to be up and operating your CNC to full production for at least three months, depending on the type of machine and training as well as your operator.
Do I Have To Hire A Computer Geek To Operate My CNC?
In some cases it is a good idea to hire someone with good computer skills. In other cases computer skills can be learned. The most important prerequisite is that the potential operator be open to new technology and not be afraid of the machine.
Unless you hire someone with prior experience, it is going to take time to get your labor up to speed. I have found that the best operators can be found coming right out of high school or a technical college with a computer background. This is not to say that the average fabricator can't learn, but the right person needs to be chosen.
What To Look For When Purchasing A CNC
There are many CNC manufacturers out there and the number is growing. There are also many options available. You will need to decide which options you will need. Many times some of these options are useless for what you will be using your CNC for.
I have seen dozens of shops using a CNC for sink cutouts only. Set up properly, this can be a big savings because sink cutouts can be a major bottleneck in your shop. On the other hand, it can also cost you more. How you will use your CNC and what type of work you are doing all need to be considered and evaluated before you purchase a CNC.
In addition to the different options available, there is another important question to ask when considering a CNC: How quickly can I get my CNC repaired or is someone available to answer my question or solve my problem? If it's Friday afternoon and you have a job to be done on the CNC that is getting installed on Monday and the CNC shuts down, what do you do? You get on the phone and call to find out how to resolve the problem. You call and find out the office is closed and won't reopen until Monday. I have had this happen to me, and in my opinion, service is everything. Ask about a company's service policy. Are they available on weekends? How quickly will they return a call?
You will also need to know if parts are stocked in the United States for your make and model. Imagine the same scenario above and you find out that you need a new spindle but one has to be ordered from overseas and it's going to take four to six weeks to get it in. Can you wait that long?
Don't buy a CNC based on a test drive. I can remember a friend of mine who bought a new Jaguar many years ago and thought it was the best car on the market. He test drove it, bought it and spent the next three years visiting the dealership every month for repairs. If he would have asked current owners and did a little research, he would have discovered that the model required a lot of maintenance and repair work. The best way to get feedback on a make and model of a particular CNC is to visit someone who has one. Ask the dealer for three to five references and check them out. The dealer is not going to give you any customers that are unhappy with their machines; however, if you ask the right questions in the proper way, you will get the answers you need. The following are a list of questions I would ask:
- How long have you had the machine?
- How long did it take to get to comfortable operating it?
- How many service calls did you have during the first year of operation? How many do you have now?
- When you have a problem, how long does it take to get a return call or to get a technician on-site?
- Would you buy this same machine again? Why or why not?
- Did you find this machine helped with your productivity or not?
- Was the machine hard or easy to learn?
- How was the training offered? Was it worth it?
- Did the dealer follow up once you were up and running?
- How many kitchens or lineal feet are you getting per day?
Of course there are dozens of additional questions you could ask. I would also ask if it is possible to visit the shop and see the machine in operation. I have found that many fabricators are open to this and will be glad to help. It doesn't hurt to ask and may be worth a trip or two. You can also go to several of the fabricator forums online and post questions.
Some of the trade associations may also be able to help you in gathering additional information.
Concerns And Questions About CNCS And Operations
Over the years I have had many questions and experienced some concerns with not only CNC technology, but also operation problems as well. The following are some of the most common questions I've encountered:
My Best Fabricator Can Cut And Polish A Sink In A Lot Less Time Than A CNC, So Why Should I Buy One?
This is absolutely correct. I know I can cut out a Kohler 2210 and polish it and have it ready in 45 minutes, where as a CNC may take the same or even longer. The advantage to having a CNC do it is that it can do it again and again and again without getting tired and without needing a break. I'm not sure I would want to do 10 cutouts in a row, day in and day out.
I Know Many Fabricators That Have A CNC And They Are Pulling Pieces Off And Putting The Final Polish On By Hand. Doesn't This Defeat The Entire Purpose Of A CNC?
This is partially true. Since the tooling of a CNC runs parallel to the edge, lines in the final polish are common. However, depending on the profile they may be hardly noticeable. I have also found that many times it is not the CNC, but a combination of the type of tooling and the operator's experience, that will leave a less than desired polish. I know several CNC operators who can achieve a hand-polished look on a CNC, but this requires the proper tool selection, tool setting and experience.
What If I Add A Second Or Third CNC? Do I Have To Have An Operator For Each CNC?
Adding a second or third CNC is where the savings really come into play. One CNC operator can run several CNC machines. I know of one shop that runs six CNCs and one operator runs them all. Another way to get more bang for your buck and to not only increase productivity is to add a second or third shift.
The Salesman Told Me That I Can Set Up My Last Piece At Closing Time And The CNC Can Operate Unattended?
If the salesman told you this, it is clear to me he has no experience in CNC operation. I would never operate a CNC unattended. Things can and do go wrong. For example, I was running a brittle granite and after about halfway through, a piece of the granite broke off. I was able to catch it and prevent a disaster since I could hear something was wrong. If the machine was unattended, it could have easily ruined the tooling or, worse yet, I could have broken the spindle on the CNC — just a simple $10,000 mistake.
The selection of a CNC should be taken very seriously. There are fabricators who really don't need one, and there are fabricators who think they don't need one and can benefit tremendously. The stone industry is becoming more and more advanced and technology is moving to the front. Do your homework, make an educated choice, and you will benefit from this technology.
About the author:
Frederick M. Hueston runs the National Training Center for Stone & Masonry Trades, Asheville, NC 28806, www.ntc-stone.com, and can be reached at Fhueston@aol.com.
author: By Fredrick M. Hueston