A Coordinate Measuring Machine (CMM) is like a human in a modern workplace: it sometimes needs to adapt to emerging technologies to remain relevant. As offices transition from paper and filing cabinets to software and computer operating systems, so too does an old CMM need to adapt to the latest measurement software and enhancements within the electronics industry.
But they say that “you can’t teach an old dog new tricks!” NOT true! It CAN be done, but it’s not easy and this is where our expertise comes in.
CMMXYZ recently took on a massive retrofit project that did indeed teach an old dog new tricks. The “old dog” in this case was a 33-year-old “monster” CMM that had been sitting in storage for 3 years.
This CMM retrofit project was exceptional because this machine is HUGE! When fully assembled, this beast will stand 20 feet tall, take up 500 ft2 of floor space and tip the scales at nearly 38 000 lbs! But, regardless of size, most of our retrofit projects follow a basic template from start to finish. What begins as a mechanical project is then refined by integrating pneumatics and electronics and finally ends with an onsite calibration.
To successfully retrofit this CMM, we needed to coordinate three vastly different skill sets:
- Machine Builder
- Electronics Specialist
- Calibration Group
The first phase of this project saw most of the heavy lifting – literally! To physically move the massive beams and columns was a chore, but once in place then it was time for our Machine Builder to step in.
With more than 30 years’ experience under his belt, our Machine Builder was more than capable of taking on this massive project! In addition to overseeing each phase of the assembly, he had to make use of our in-house tool room to re-machine and hone the Y-axis drive racks, clean and service all motors and gear boxes and completely re-align the Y-axis split beams.
Once the mechanical modifications were complete it was time to focus on the pneumatics. On a coordinate measuring machine, pneumatics (air lines) play a crucial roll in the machine’s overall performance since the bridge rides along air bearings. On this project, the CMM had to be completely stripped and the entire pneumatic systems re-designed.
All in all, it was nothing new for us, but the sheer size and weight added an extra challenge at this initial phase of the retrofit. At over 38 000 pounds, it took us 4 days to dismantle and prepare for final shipment.
The electronics upgrade is really the “meat and potatoes” of any retrofit. All the mechanical re-alignment and airline re-design would be for nothing if we couldn’t get the computer to talk to the machine.
If the motors and gear boxes are the muscle of the CMM, then the Controller is the brain. During a retrofit, the original controller is replaced. While the unit itself is quite robust, the electronic components within the controller and wiring are subject to enhancements within the electronics industry, and production of parts such as circuit boards may have ceased; it is essentially obsolete.
On this retrofit, we adapted a Hexagon RC1 controller, Renishaw PH10M probing and PC-DMIS CAD++ software. The RC1 retrofit controller caters to medium and high-end bridge, gantry, and horizontal-arm CMMs supporting up to five configurable axes and providing up to 800 W output power.
To successfully integrate this new controller, our electronics specialist needed to upgrade all the wiring to both the CMM motors and the new Renishaw Probe Head. This is highly skilled and tedious work!
Once this work was done, we were able to interface the latest version of PC-DMIS running on a Windows 10 PC and verify communication. It is interesting to note here that the year this CMM was built, Microsoft’s Windows Operating System was only one year old!
The final phase of this project involved dis-assembly, crating, re-assembly and finally levelling and calibration onsite. Once the machine arrived at its new home, our CMM calibration group required 9 days for assembly, install, precision levelling and calibration.
Even before we arrived, the preparation of the site was no small task. The foundation for this machine required a total excavation depth of 18 feet and needed below grade shoring due to proximity to the building’s footings. Shoring is when you build a re-enforced retaining wall inside the excavation pit to prevent the earth from shifting. This phase alone took 2 months to complete.
Once the dust settled, we were able to achieve a volumetric accuracy of 0.023 mm: that’s a 31% improvement on the OEM’s spec of 0.033 mm! Keep in mind that the working volume of this gantry CMM is 2540 mm (X); 6300 mm (Y); 1800 mm (Z).
It is fair to say that this beast is now more capable and indeed more accurate than it was when first unleashed in the world back in 1986. This project was a success on many levels, but perhaps the greatest achievement was that our team were able to deliver a “good as new” CMM at one-third the cost of a new machine of this size and accuracy.