Coordinate measuring machines (CMMs) are becoming more versatile as providers offer more sensors, advanced automatic probe changers and better software. Sensors to choose from include touch probes, scanning analog probes and various flavors of optical and interferometric sensors. Having multiple sensors means flexibility, which is often useful when a complete assessment is needed, such as first article inspection (FAI).
But not all applications need such flexibility.
As manufacturers are pressed into making more metrology inspections in production, using a highly capable, multi-sensor equipped CMM can become a bottleneck. Measuring with multiple sensors can be slow and a challenge to create the measurement program. Simplicity and speed are what industrial users need today.
Entering the stage is the tailored CMM, a system designed to meet these needs and reduce headaches for manufacturing engineers. While complete product packages are starting to be offered, tailored integrated systems continue to show their value as well.
Integrate a Solution
Measurement bottlenecks in the aerospace industry are especially noticeable with the precision parts used in turbines, according to Ryan Toole, North American product manager, automated measurement systems for Hexagon Manufacturing Intelligence, North Kingstown, R.I. Tolerances in turbine blades are tight, and they require 100 percent inspection. More importantly, the demand for aerospace engines is projected to ramp-up dramatically, meaning even faster and accurate inspection is needed.
In one example, Hexagon integrated a custom solution, including software, by building it around a single sensor. “We [did that for a customer], developed a high throughput and accuracy, or HTA, system using our HP-O sensor. This is a non-contact scanning sensor for coordinate measuring machines (CMMs),” said Toole. HP-O is based on frequency-modulated interferometric optical distance measurement, boasting a spot size of 11 μm. The company equipped a standard Hexagon Global S CMM with this HP-O sensor, adding a rotary table to get true five-axis scanning for a high-throughput solution. (Another Hexagon sensor available since August 2021 is the HP-L 10.10. The sensor is available on select Hexagon Global S CMMs using a DC241 or DC800 controller and can be used for blades and other aerospace applications.)
‘Productize’ a Solution
Another approach is to offer a standard, off-the-shelf product. Building on the integrated approach, Hexagon “productized” a turbine application into the Leitz Reference HP HTA solution, built on the Leitz Reference CMM. This CMM offers higher accuracy than the Global S and has an integrated rotary table. This solution, according to Hexagon, increases the speed of blisk inspection by as much as 50 percent compared to traditional methods. To help productize the procedure, Hexagon created a Bladed Rotors Measurement (BRM) module within its QUINDOS software.
Toole thinks the biggest benefit in this solution might be how it reduces programming time. With the BRM module in the HP HTA solution, a user creates a measurement program as much as 70 percent faster than traditional methods. “When we interviewed our customers, we found it can take, on average, months to create a measuring routine for blades and blisks,” he explained. “These routines are incredibly complicated and minor errors in coding can lead to big troubleshooting issues.”
He described the BRM as a drop-down menu that guides a user through creating a routine step-by-step. The module optimizes the inspection path using AI techniques, according to Toole. Visuals provide instant feedback, so users don’t have to step through i++ compliant QUINDOS code.
Adapt a Solution
The need for easy programming is based on changes in who is doing the programming. “We’re seeing a lot of customers buying a CMM for the shop floor because they’re required to meet new tolerancing requirements imposed by their customers,” said Peter Rau, senior CMM applications engineer at Mitutoyo America Corp., Aurora, Illinois. This seems to be across the board, in automotive, aerospace, and medical. “We’re seeing fewer hand tools and more CMMs.”
This move to the shop floor also means the skill base is changing and evolving. “Shop floor professionals and manufacturing engineers, familiar with programming CNC machine tools, are now being tasked with programming these shop floor CMMs,” explained Rau. Given that programming CMMs is one of many tasks they are asked to do, they need more out-of-the-box” aids than a dedicated and experienced CMM programmer would.
Along with the increased use of CMMs for production are a growing number of not just production users, but first-time users, according to David Wick, product manager for Zeiss Industrial Quality Solutions, Maple Grove, Minn. “This is across the board, in small machine shops, in large aerospace applications, and in industrial applications,” he said.
Zeiss has long catered to the needs of the shop floor with its DuraMax and CenterMax line of equipment that the company often touts as flexible gages (rather than shop-adapted CMMs). Why are packaged solutions becoming so popular? “Users get the software, the accessories, the computer, the installation, all for one package price. And these are aimed at first-time users of CMMs that might not know exactly what they need,” he said. Once they use it and find their needs, the CMM can be upgraded with additional sensors and programming. “Virtually every CMM that Zeiss offers has a complete solution package with it,” said Wick.
Robotic movement of parts is also an important element. “We’re seeing more requests for automation to include with our CMMs, like the Apex V series,” said Rau. “We are also seeing more requests for complete turnkey systems, though for us it is still more the exception. That is more for an application that is running thousands of parts that only vary between two or three different part numbers.”
Automation is often a needed ingredient in a smart factory or smart machining cell. In automating a cell with a machine tool, measurements are typically fed directly back to the CNC controller for a closed-loop, lights-out operation.
Smart Factories and Industry 4.0
But even for CMMs accessing more than one sensor, ease of programming is paramount. The next best thing to having a system that is “out-of-the-box” ready is to have a programming routine for a CMM come automatically with a part’s CAD description. That is coming with the growing acceptance of model-based definition (MBD), where GD&T information is attached to CAD models. When such CAD models are loaded on the shop floor into programming software like Mitutoyo’s MiCAT Planner, a program can be automatically generated. “With the CAD model and the specification of the CMM, all the probe angles, measuring volume, and the type of probe system are taken into consideration when generating a program,” said Rau.
It is not just the inputs that are becoming common; there is some commonality across industries in outputs as well. “Virtually everyone needs to summarize and report measurement results in a format that’s usable by themselves, or by their customer,” said Wick from Zeiss. “For example, medical device companies have to keep and produce records that could pass an FDA audit,” while aerospace companies need documentation for first-article inspection. Automotive suppliers must supply PPAP documentation.
“Another issue is that virtually everyone wants to remotely monitor machine status and record machine events,” he said. “And you have to have the right software to be able to let them do that remotely.” He also noted that closed-loop machining is becoming more popular, with a CMM sharing measurements with the controller to make adjustments. “Finally, many people want to integrate robotic loading and unloading of parts to the CMM so that the CMM is more productive, with more parts per hour, more parts per day.”
Long-Term Trends for CMMs
How do these issues affect the technical trends in CMM offerings? Two things stand out, according to Wick. The first is the drive for more productivity by having more than one sensor available on the CMM but letting the CMM choose “smartly” which one to use without a person intervening. “The second one is the increased need for remote monitoring or remote health services to keep customers aware of machine status,” he said. That could be just a simple smartphone dashboard that looks at machine status through a cloud interface, or it could be a service that looks at the machine remotely and supplies some type of predictive health maintenance or predictive health assessment. Look for CMMs continuing to be smarter and more connected.
To achieve this goal in its ultimate form means that the supporting technologies around smart factory concepts also need to mature, in particular MBD and attaching valid and complete manufacturing and quality information to a CAD model. This will force upstream designers (and design software) to become not only more adept at attaching that information, but also get in the habit of doing it in the first place.