Above the pins and blocks and calipers, above the micrometers and the air gages, sits the Maharajah of measurement, the Pasha of precision: the Coordinate Measuring Machine (CMM), the ultimate device for accurate and repeatable measurements. In our post about gage selection, we mentioned a gage selection pyramid. Atop this pyramid sits the Coordinate Measuring Machine (CMM), the ultimate device for accurate and repeatable measurements.

The size of a sample can be measured in all three dimensions using a CMM, which is a computerized and programmable piece of machinery. It looks like an enormous granite table with a robot arm mounted to a bridge or gantry that quietly floats around, gently touching the tip of a slender touch probe to the sample that is sitting in the middle of the table. After that, there is a beep. And then it beeps again, making a sound that is eerily reminiscent of a television show version of an operating room in a hospital. Each beep denotes a different point that was taken into account when analyzing the part sample. The attached computer generates a three-dimensional map of every point quality inspection china finds and plots those points against an internal computer-aided design (CAD) model of where those points should be versus where those points actually are. After that, it will tell you whether or not your contribution is a good one.

CMMs have the ability to measure complicated parts quickly, precisely, and repeatedly. However, they are notorious for being picky and demanding, necessitating the use of specialized air-conditioned rooms as well as highly trained programmers in order to achieve the desired outcomes. Many people believe that coordinate measuring machines (CMMs) are the pinnacle of all measurement technology. Others will argue that a skilled layout tech working on a surface plate can accomplish the majority of what a CMM does, despite the fact that the CMM does have its applications. In most cases, the truth can be found somewhere in the middle of the argument.

In light of everything that has been said about CMMs, how can you determine whether or not you really need one?

Your coordinate measuring machine (CMM) is capable of providing you with accurate and highly repeatable measurement results on even the most difficult and complex parts if it is properly maintained, calibrated, programmed, and operated. However, repeatability and reliability still have their limitations, and they come at a cost, which may or may not justify the investment for every organization. Both of these characteristics, however, come with the benefit of reducing risk. Now that we have that out of the way, let's take a high-level look at the potential costs involved in acquiring it.

How much will it cost for me to own a CMM?

Equipment

What is the total amount of money you have allocated to your quality budget? CMMs can be quite expensive. A compact CMM that possesses only a few useful capabilities will likely cost you somewhere in the region of $30,000. It is common knowledge that bigger is better, at least up to a certain point; however, prices can easily rise to over $100,000 or even $250,000. Other costs to consider are the following:

• You will need to store it in a room with controlled temperature and humidity; ideally, you will also be able to isolate it from the vibrations caused by the production equipment

• Additional measuring heads and probe tips, which may not be included with your CMM's programming, training, and maintenance services

• After you have finished preparing the site, installing, and calibrating your new CMM, you will then be responsible for operating expenses, which include the following items:CMM programmer costs (including salary, benefits, and training)The cost of time and transportation for operator trainingYour software's support and maintenance contract for the CMM system

• Calibration costsBoth brand new and refurbished probe tips

   

You will receive some training in conjunction with your CMM, but keep in mind that it will only cover the fundamentals.
The capabilities of the CMM's programmer have a direct bearing on the accuracy of the instrument's measurements. Programmers with years of experience are familiar with the programming algorithms that are used by CMMs to calculate the locations of the points that they measure. They are aware of how many points should be awarded for a variety of characteristics under a variety of circumstances in order to guarantee accurate results. They are aware of the capabilities and limitations of the device. And because not all CMMs use the same programming and operating systems, the programmer working on your machine will need to be familiar with the language that is used by your particular machine. All of this points to the fact that programmers are in high demand, and as a result, their pay rates are high.

CMMs typically have an annual fee that must be paid for maintenance, programming updates, and other related services. This fee is commonly referred to as a seat license, and it can cost several thousand dollars annually. Additionally, you will need to pay several thousand dollars annually for calibration. The probe tips themselves are frequently the CMM component that sells for the least amount of money. Depending on their size and variety, probe tips typically cost less than one hundred dollars each. Just keep in mind that you might need twenty or thirty of each kind of sample in order to accurately measure everything that comes your way.

What are the advantages of being the owner of a CMM?

Examine the ComponentsIt is possible for inspection times to be up to ten times faster than measurements taken manually, which results in a significant reduction in labor costs.

In addition, that speed has the potential to cut down on the amount of downtime that machines experience while they wait for first-piece approval. For illustration's sake, if a complicated part has a hundred different characteristics, it might take an entire day to check it using hand tools on a surface plate, but a inspections companies can do it in fifteen minutes.

If we assume that the time spent on inspection has a cost of $50 per hour for labor and overhead, then a reduction in inspection time of approximately seven hours has just saved us a total of $350. If you multiply that by the average number of inspections, which is one per day, you'll spend more than $90,000.00 in just one year. The CMM starts to look less like a capital expense and more like a tool that can help reduce costs when you factor in the revenue generated by having a machine cutting chips seven more hours per day because it isn't sitting and waiting for the go-ahead from quality. This is because the machine isn't sitting and waiting for the go-ahead from quality.

To Satisfy the Strict Demands of Our Customers
You can use a CMM to help you meet the increasingly demanding gaging requirements of your customers. Imagine you are working in a machine shop that transforms castings into finished parts. These finished parts have very precise tolerances and a large number of critical features because they are intended for a customer application in the medical or military fields. There is a good chance that your gaging will need to comply with either the Gage RR requirements or the Cpk requirements, or both.

Assuming that your quality audit is properly calibrated, operated, and maintained, that the program is well-written, and that you have a well-thought-out fixturing program, you should have no problem meeting a 10% Gage RR requirement, and you should be able to trust the Cpk numbers that you are getting. If all of these conditions are met, then you should be able to trust the Cpk numbers that you are getting. It is possible to accomplish the same goal using hand gages, but it will take significantly more time and effort than using a CMM, which, due to the fact that it is computer-controlled, is inherently more repeatable.

Create more effective components.
A CMM can assist with salvaging scrap and reworking. This one is easy to understand. You will be able to produce more good parts and fewer bad ones if your measurements are accurate and repeatable. Because of this, there is less waste and rework that needs to be done, and every dollar saved goes straight to the bottom line. The reasoning behind this is sound, despite the fact that it is impossible to provide an accurate estimate of how much money your company could save.

Make Your Organization Stand Out
Your company's strong point in the sales department is its CMM technology. Let's be honest here. Spend a few minutes perusing the websites of reputable contract manufacturers in the industry. Look at the "Quality" part of the website. There is a good chance that each one of them possesses at least one Factory Audit Service and that they will include it on their list of available tools. Why? Because current and potential clients appreciate being able to see that they have a CMM.

People have a tendency to trust the results you give them if they come from a CMM, regardless of whether or not they should. They are, to a certain extent, correct in this assessment. The results obtained from a  are, on the whole, reliable and accurate. However, a  is not without its limitations, and it is important to be aware of these constraints.