Inspections: What You Need to Know
Does your company need inspections?
Often times, it is important for a project to have extremely accurate measurements that cannot be taken or assured by hand. Furthermore, the process to take these by hand is lengthy, dangerous, and costly. An inspection by a coordinate measure machine (CMM) may be necessary to meet the project requirements for accuracy, time, and cost. Purchase, maintenance, and use of the machine require a large number of funds and expertise, but fortunately, a CMM inspection can be ordered for your project at a much lower cost than purchasing and operating your own machine.
What are Inspections?
A Coordinate Measuring Machine inspection (CMM inspection) uses a device that takes extremely accurate measurements of a physical object at a large set of data points. This data set can then be fed into a number of different computer applications to render the necessary information about the object of interest. CMM inspections can be done on very small or delicate parts or even extremely large or heavy parts.
A variety of different coordinate measuring machines exist with capabilities to handle nearly all the current needs of a number of different industries. The needs of these different industries have actually caused advancements in the development of these machines. A CMM can take methods via a contact probe that uses a small device head that makes contact with the object and takes measurements as it is moved. Some of these machines that use contact move across an object, some move around an object, etc. The different types of contact probes help to get the best measurement for the application. Some objects require the use of a contactless method meaning a method that does not touch the object. This is extremely useful for very delicate objects. Two of the main types of contactless machines are optical CMMs and X-Ray Computed Tomography (CT) CMMs. CT CMMs are extremely useful for parts with complicated internal geometries and forms that would be difficult or impossible to measure with a probe or optical sensor. Also, fortunately, these machines come not only in large permanent installations, but also some portable machines are available for use as well.
The use and development of CMMs fall under metrology, or the study of measurement. With a CMM, the data is collected via a probe, optical sensor(s), or x-rays. The collected information represents data points in 3-D space defined by the CMM. Once the data is collected by the CMM, it is fed into a program that processes this data and is able to give computed measurements, surfaces, angles, depths, thicknesses, etc. for the inspected object. It is even possible to process the data into points that can be used in CAD applications.
The raw data that is produced by a CMM needs processing, but once the data is processed, a usable and interpret-able set of points is created. Depending on the need of the particular project, these points can be further processed to a finished product to troubleshoot an issue with a part or to create a new part from reverse engineering.
Reasons for Inspections.
The reasons an inspection might be needed are as varied as the reasons that a measurement may need to be taken. Some of the applications of an inspection may even be surprising. Did you know that a CMM inspection may be helpful in detecting failure or weakness in a part currently in use?
Cause for Inspection
Many times a project will require that measurements be taken with an extreme accuracy to ensure that the outcome has the precision that is necessary and expected in today’s industries. These inspections can be done at the beginning of a project to ensure designs are made to fit the available inspections; during the project to ensure that design processes have stayed true and prototyping is performing as expected; at the end of a project to verify measurements before production or closing of a project; or even post-production to ensure that quality control requirements and expectations are being met.
Problems that can require inspections.
A CMM inspection might also be required for some issues that arise. It is not always possible for a problem in a part to be detected by the human eye or sense of touch. A CMM can accurately look for deformations, stretches, contractions, microfissures, etc. in a piece that would not otherwise be detectable. Finding these issues early, could actually prevent expensive and/or catastrophic failures in machinery and reduce downtime. Using X-Ray CT CMMs, it is actually possible to detect internal stress in a part that would go undetected until the catastrophic failure of the part. The use of CMM inspections have the potential to save quite a bit of money for a company.
Detail and Accuracy
Due to the wide range of industries that make use of CMM inspections, the detail and accuracy have advanced far beyond the necessity of most projects so the most extreme applications can have their needs met by the numerous types of machines and their capabilities.
Just how detailed are the Inspections
A small number of international standards have been developed by metrologists (those who study measuring) for calibration of CMMs around the world. Depending on the machine that is needed to be used for a project, the accuracy of the inspection can vary a bit within the limits of these standards. The majority of CMM machines using contact probes are easily accurate within a few microns. For the most stringent needs, the accuracy of a contact probe, however, can get less than 1 micron (or .00004 or 1/20 the thickness of a human hair) in expected error. Contactless methods, while still continuing to improve with contact methods, are still able to come in at 2-9 microns accuracy.
Turnaround On Projects
Time is money, so turn around time is a definite consideration for any aspect of a project. Fortunately, CMM inspections tend to have a quick turn around time for your project and definitely have the advantage over manual methods.
How long does it take?
The time it takes to complete an inspection varies based on the size of the part(s) being measured and the amount of accuracy needed from the measurements. For example, a small piece needing less accuracy can be done in less than an hour. In general, for a CMM inspection using a contact probe for inspection, you can expect 1-3 hours for the physical measurement portion of the inspection to take place. Some contactless methods are able to complete in under an hour. Once the data is taken, it must be processed, but thanks to modern computing power, this can be done in a relatively quick amount of time. Again, the actual amount of time will depend on the size of the object and how much data is collected for accuracy. Regardless, the traditional manual process of measuring, checking the measurement, and processing the measurements will take more time than the entire process using a CMM.
With the wide range of uses for CMM inspections, chances are many of the projects out there could benefit from making use of this process at some point. The costs of owning, calibrating, operating, and maintaining a machine can be out of reach for many companies though. Fortunately, ordering a CMM inspection is a possibility that comes at MUCH less than the cost of even buying a CMM. Contact the experts at Engineered Mechanical Systems today to find out how they can assist you with your measurement needs for any project. Their capabilities are likely to fit your needs at a cost that can make your company competitive in the field.