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Why CMMs Are Manufacturing’s Evolutionary Winners

Why CMMs Are Manufacturing’s Evolutionary Winners

The advent of new, high-performance measuring technologies could have posed an existential threat; but instead, the CMM has proven its resilience and remains key to metalworking manufacturers’ long-term strategies. Article by Sea Chia Hui, Hexagon Manufacturing Intelligence.

The DEA TORO CMMs can be employed as metrology stations in the development and engineering departments for supporting industrial design of complex contoured shapes, as well as flexible gages for process control in a shop environment.

For more than 40 years, the accuracy of coordinate measuring machines (CMMs) has guaranteed them a central role in metalworking companies’ quality control processes. The advent of new, high-performance measuring technologies could have posed an existential threat. But instead, the CMM has proven its resilience and remains key to metalworking manufacturers’ long-term strategies. This is because rather than replacing CMMs, new measuring technologies are complementing their strengths as quality control capabilities expand across the production cycle.

Adapting to Accelerated Evolution

A whole gamut of machines from smartphones and cars through to PCs have benefited from rapid technology advances that include lower cost of processing, higher performance software, and faster network connectivity. CMMs are no exception. But what makes CMMs different is their unique robustness and adaptability. A sizeable number of CMMs in use today have been in operation in excess of 20 years, kept up to date by retrofitting software and sensor systems.

At the heart of the CMM’s longevity are its unparalleled accuracy and durability, combined with an ability to be upgraded for new applications and working methods. Unlike many other machines, there is no need to replace a CMM in order to gain access to new functionalities. Manufacturers simply change a CMM’s controllers, software or sensors, while keeping their principal investment intact for years.

Increased Versatility and Cost-Effectiveness

Recent advances in measuring software, sensors and data analysis systems have played a crucial role in transforming the ease-of-use of CMMs, opening them up to new applications while increasing their measurement throughput.

One of the consistent benefits of a CMM has been its ability to provide 2-D touch probe-based measurement of unparalleled accuracy, precision and repeatability. But today’s metalworking companies often want to combine the accuracy of a 2-D probe sensor with the fast 3-D data capture offered by optical sensors.

Contactless measurement, for example, makes sense for sheet metal parts where throughput and speed of measurement are of the essence, or for metal parts on which a probe would leave an undesired mark. And because laser scanners can be used to create solid models from surface profiles, they are the ideal tool for reverse engineering and rapid prototyping.

Improvements in multisensor systems mean CMMs are ideally placed to support both tactile and 3D non-contact measurement. Crucially, manufacturers are able to opt for CMM software and machine controllers that enable seamless transfers between different non-contact or tactile sensors within a single inspection program. This enables a CMM to automatically switch between different sensors to capture a full metrological report even for complex parts.

And because software systems can be programmed to instruct the CMM to automatically change over sensors, multisensor systems can be left to run untended, whether they’re using touch trigger, optical, chromatic white light, laser point, or laser line sensors. The supporting software also makes it easy to create a graphical analysis of the captured CMM measuring data and overlay it on three-dimensional CAD models to compare the real data with the nominal data. This visual representation makes anomalies easy to identify, allowing operators to take decisions quickly on the shop floor.

And since the advent of intuitive software systems and greater levels of automation have made CMMs simpler to operate accurately, their use has been opened up to a wider range of employee skill sets and levels of experience.

Dealing with the Task in Hand

Not every application will need the same software package—much will depend on parts to be inspected and the complexity of their geometry, and the extent to which manufacturers want to analyse captured data and use it to inform their design, engineering, and production processes.

Similar factors shape the choice of a CMM, which is determined by the volumes of the workpieces to be measured, the tolerances required, and the desired throughput speed. Gantry CMMs, for example, continue to be a popular choice in the automotive, shipbuilding, and aerospace industries, because they are designed to accommodate the measurement of very large sheet metal parts. And they can be adapted to meet different accuracy and productivity requirements.

Parts such as aeroblades or car powertrain gears, for example, need to attain very tight tolerances, which requires the use of high precision CMMs. In contrast, the manufacturers of car bodies or aircraft fuselage are likely to seek a CMM optimised for throughput rather than precision.

When it comes to smaller parts, manufacturers in the metalworking industry have a choice of bridge CMMs that again provide differing levels of throughput, accuracy and flexibility, depending on the application need. Manufacturers can also consider gaining productivity benefits by installing CMMs on the shop floor.

As we have seen, the CMM’s versatility is at the root of its ongoing success, offering manufacturers the possibility to closely match a CMM’s measuring capabilities with their application needs. Whether a manufacturer is looking for an entry-level CMM or the most accurate measuring machine on the market, with the right supplier they can be confident of deploying a cost-effective CMM solution that future proofs their business for years to come.

 

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Benefits Of Improved Multisensor Measurement

Benefits Of Improved Multisensor Measurement

Multisensor systems have evolved considerably over the years as the component technologies for motion control, optics, lighting and cameras have improved. Tim Sladden, Quality Vision International, tells us more.

Multisensor coordinate measuring machines that combine vision, touch and laser sensors have been used in manufacturing quality control for nearly 20 years. Many still recall the early days of multisensor systems when the primary sensor worked well, but the additional sensors – sometimes added almost as an afterthought, offered limited capability and poor accuracy.

Today’s multisensor systems have advanced to the point that all sensors now offer full capability and accuracy. Limitations inherent in earlier designs have been removed through more careful integration of the sensors with the measuring axes.

Improvements in the metrology software are the greatest enabler of comprehensive multisensor capability. Measuring software has evolved in ways that allow each sensor to be truly integrated and measure with consistent uncertainty at all times.

Along the way the economic benefits of multisensor measurement systems have become clear: reduced capital and calibration expenses, shorter learning cycles, added flexibility and convenience, and most important – lower overall uncertainty in the measurements.

Figure 1

Manufacturing Processes Improved

To highlight the full range of capabilities of today’s multisensor measuring systems, let’s look at three types of parts and how their manufacturing processes have been improved by using multisensor measurement.

In Figure 1, we see a femoral implant being measured with a calliper. This is not that simple orthopaedic implants are among the most complex-shaped devices being machined today – there is simply no way to measure the critical dimensions and form of these parts with a single sensor system.

For starters, the highly polished surfaces of knee implants are extremely sensitive. Even casual contact by a tool or gauge could damage the surface finish, causing friction that could lead to improper fit and ultimately pain in the patient receiving the implant. To measure these parts, a variety of non-contact or minimally invasive tools – vision optics, lasers or very light contact probing force – are needed.

More importantly, femoral implants consist of a series of curves controlled by profile tolerances, each of which is simultaneously constrained by the material condition of one or more datum features. These geometric dimensioning and tolerancing (GD&T) conventions enable the designer to specify the form of the part exactly, but make verifying the part a challenge. To properly measure this part, the measurement points must be collected, and then fitted to the CAD model in their entirety in order to ensure all material conditions are properly evaluated. Data from tactile, scanning, laser and optical sensors needs to be integrated with the CAD model, and powerful software is needed to perform the GD&T evaluation.

Modern System

Enter the modern multisensor system. A system with telecentric optics, through-the-lens laser, and a micro-scanning probe can measure the outside dimensions, profiles and curves without damaging the part, and compare the data directly to the CAD model.

The manufacturer of this part faced high re-work and scrap rates, in spite of careful machining, polishing and measurement. Compounding the issue were disputes about dimensional conformance between different measurement techniques.

Multisensor measurement solved the first problem, by accurately measuring the critical features without damaging the part. True multisensor software enabled the data to be fitted to the CAD model and applied the GD&T standards properly.

This combination enabled the manufacturer to eliminate disputes about measurement accuracy between different gages, and ultimately reduce the number of finishing steps needed to produce the part to customer specs. All of which reduced scrap and re-work costs substantially.

Our next example is a large casting with a variety of machined surfaces, mounting holes and bearing ways on each of its four sides. This part has more than 50 discrete dimensions that must be controlled to ensure fit and function within the assembly it is part of. Many of these dimensions relate to datums on opposite or adjacent sides of the part. Ideally, the part would be measured in one set-up, without having to re-stage the part to enable measurement of all its surfaces.

While access and tolerance issues make a tactile scanning star probe (Figure 2) the ideal sensor for the bearing tracks, other features such as the small blind holes on the adjacent face are best measured using video, while surface flatness measurements on the mating surfaces are best made using a laser. The custom made flip fixture in this photo automatically indexes the part to present each side to the sensor array for measurement. This casting is a component in a complex assembly that relies on machined-in precision for the reliability of the overall mechanism. Thus, measurement is critical to the overall quality of the end-product.

For the maker of this part, multisensor measurement offered a number of benefits. Most significant was the time savings of being able to confirm all dimensions on one system, rather than having to program, stage and measure on several different systems, then combine and compare the data to determine if the part met spec. Another significant benefit is that the multisensor system offered the same uncertainty regardless of the sensor used.

In our third example, we see another complex machined casting – in this case, hydraulic transmission housing. This part presents a challenge to measure in a single set-up. Not only are there dimensions along the outer stems and top flange, there are dimensions on the seal surface and spline more than six inches deep inside the part. To access all these features in one orientation, long working distance optics and a LWD laser are needed to reach features at the bottom, as well as scanning probe capability to measure inside dimensions on the stems and interior profile.

Once again, the combination of scanning probe, laser and video measurement makes quick work of measuring this complex part. The laser quickly gathers a large pattern of data from the mating surface on the top flange. Flatness on this seal surface is critical. The scanning probe measures the interior profile in several locations, as well as the inside diameters of the in-flow and out-flow stems to calculate interior volume and flow rate characteristics. The long working distance laser also reaches to the boss on the inside of the spline for a flatness measurement, and long working distance optics quickly measure the gear teeth and ball bearing positions in the ball spline.

Each of these three examples illustrates the value inherent in a high quality multisensor measurement:

In all cases, it was possible to measure the entire part on one measuring system – saving the cost of buying and maintaining multiple measuring systems, and eliminating the differences in uncertainty between differing measurement technologies.

The range of sensors available enabled the key dimensions to be measured using the best sensor type for the feature without compromising efficiency or accuracy. Deployable and long working distance sensors help eliminate interference between sensors and minimise offsets that use up valuable measuring range.

 

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Interview With Mr. Tim Sladden, Vice President Of Operations – Asia At OGP

Interview With Mr. Tim Sladden, Vice President of Operations – Asia at OGP

Asia Pacific Metalworking Equipment News is pleased to interview Mr. Tim Sladden, Vice President of Operations – Asia at OGP regarding OGP’s achievements for 2018, the company’s aims for 2019, and the trends that will shape the industry in the following year.

1) Can you sum up your company’s focus and achievements in 2018?

Throughout 2018 our focus was to help our customers in the Asia Pacific region meet their rapidly increasing manufacturing capacity goals.  Many manufacturers in the Electronics, Medical, Automotive and Aerospace industries were increasing their capacity, while others were upgrading existing systems with the latest electronics and software to meet unprecedented demand for advanced products which required advanced metrology solutions to help assure design and quality goals. OGP was proud to deliver a record number of optical and multisensor measurement systems and a great many system upgrades in the region in 2018.

2) What are your expectations for the regional economy in 2019?

In 2019, we expect that the rate of investment in new manufacturing capacities to begin to level off, but customer expectations for increased efficiency will continue to rise. With metrology being one of the key contributors to manufacturing efficiency, it is expected that as the trend of increased part complexity and tighter tolerances continues, demand for new metrology systems and upgrades will continue to be high throughout the year.

3) What business trends in Asia are of interest to your company in 2019?

Increased interconnectedness of all manufacturing systems from design through quality via IoT, and new 5G mobile technology will begin to impact a wide range of industries and markets.  The shelf-life of technology will become shorter as consumers continue to demand the next new thing.  Advances in medical technology and greater access to health care for patients in many parts of the world will make their mark on the industry as well.  While there are a few clouds over parts of the global economy, the general outlook for 2019 remains quite sunny.

4) What do you think is the key industry trend to watch out for 2019?

Rising expectations for makers of manufacturing equipment to provide ”process” expertise along with equipment and services will be one very important trend in 2019.  Following more than a year of significant manufacturing capacity increases, customers at all points in the global value chain will have heightened expectations for faster services that are more specialised. Manufacturers will also have to improve their production quality as well as their capacity for making products.

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