What to Know When Buying a Used CMM (Coordinate Measuring Machine)

Published by CMMXYZ on February 22, 2018

There are several things a buyer needs to consider when purchasing a used Coordinate Measuring Machine, or CMM, and especially in regards to warranty. When you buy a new CMM you get the manufacturer’s warranty, just as you would when you buy a new automobile. A used CMM machine can cost substantially less than the purchase of a new one, but the buyer bears certain risks just as one would with a used car.

What do you get when you buy a used cmm machine from us?

When CMMXYZ buys a used coordinate measuring machine at auction, or gets it on trade, we completely overhaul it. We look at the key characteristics of the CMM and make sure all measuring components are fully functional, or, if we determine they may not last in the field, we replace them. Airlines, air bearings and motors are all evaluated to assure proper functioning.

When a machine leaves our building, it is considered refurbished and essentially recertified.

The standard warranty we offer on any used machine is a 30-day money-back, repair or replace, at our cost, warranty. A new CMM machine would come with a 12-month warranty on hardware and software. Buyers who choose to buy used, may also upgrade to a one-year warranty.  

There are several important components to consider when buying a used CMM:

  • The probe system on the CMM is the tactile means of gathering information from the parts being measured; either a touch probe or a scanning probe gathers the data. Probe systems are one of the most expensive parts of the machine and are a major technical consideration. We put the probe through a mechanical test, including articulations and measurements in excess of 700 different positions. The results are then reviewed to confirm the probe system and CMM perform within, or better than, the manufacturer's specifications. With a cost of upwards of $25,000.00 USD, the probe system makes up a substantial portion of the CMM. Its proper function is essential.
  • An updated computer is another CMM essential. If the machine being refurbished is a few years old, it is normal for us to upgrade to a new system. Since technology evolves so quickly, the latest software versions may run only on a 64-bit operating system, so having the appropriate computer to do the job is a basic necessity. We prefer to provide the new computer system so that we can do a full evaluation of the machine with the new software at our facility before shipment.
  • The CMM controller provides bi-directional communication between the measuring machine and the measuring software. Many times a controller can be refurbished with updated boards and logic cards to bring it up to current specifications. In instances where a controller is obsolete, we fully retrofit the CMM with a new and current controller, fully capable of running today’s advanced scanning and multi-sensing probes. When a CMM machine is retrofitted with a new controller and new measuring software, you essentially have a new CMM, other than the frame itself.
  • Machine scales and airlines are important to the CMM's function. When the machine moves, it needs to know where it is in space; feedback from the scales provides this information. If the signal is weak, this feedback will be intermittent. We make sure there is no damage to the scales, so that signals coming from the scales are strong. If the signals are weak they may need cleaning or replacing. Older scales may be obsolete, so we offer upgrade options.
  • Floating air-bearing CMMs require compressed air, which must be clean and free of contaminants such as water or oil. During our inspection we review the condition of the airlines and the air bearings. If airlines are brittle, we replace them. If the air bearings are scored or clogged, we will lap or replace them. We make sure airlines and bearings are all functioning optimally.

Several other factors affect a potential purchase of a used CMM:

  • The environment the machine was used in previously is an important consideration. Customers considering a used coordinate measuring machine purchase want to know the history of the machine and where it was used. Was it in a foundry or a dirty environment? Such machines would need a major overhaul and probably dismantling from top to bottom to make sure there was no interference with the electronics and the controller was clean and adequate. In contrast, a CMM coming from an aerospace facility or another clean environment, where the room temperature has been regulated and there is little to no dust, would expect to be in mint condition. As a point of reference, we prepare a video of the fully functional machine, highlighting its current state of refurbishment. Although we may not have access to the full history of the machine, we provide a full synopsis of how it has been maintained, and how we assessed the CMM when it came to us.
  • A big consideration is whether replacement parts are available. If the machine is no longer being manufactured, original parts are not always readily Typically, there is a 15-20 year guaranteed replacement part availability on a CMM.
  • What age is the machine? Newer machines are a lot faster than older ones, because the technology changes over time. Since the machine runs on air, wear and tear are not really factors. Older machines have more rigid designs, and don't have slant bridge technology. Because older machines have more mass, they are likely slower, resulting in less throughput when compared to a newer machine. This factor may or may not be important to the customer, depending on how the machine will be used.
  •  Equipment set up and calibration are important. We offer our customers the option for us to install and calibrate the CMM, handing over “the keys” to their new used CMM upon completion of installation and calibration.

When a customer considers purchasing a used CMM machine from CMMXYZ we are not like an auction or wholesaler. We refurbish, retrofit, upgrade, train and support our customers. We offer everything that an original equipment manufacturer offers with a new machine and at a substantial savings for the end user. 

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