It makes perfect sense to use movable metrological equipment to measure movable objects. By Anthony Lur, product marketing specialist, Faro Technologies
In all of modern history, the world has witnessed a total of three Industrial Revolutions, with all signs pointing toward the impending birth of a fourth one. Each revolution saw significant jumps in productivity and efficiency, and corresponding reductions in costs. Today, manufacturing practices are evolving to include ‘cyber-physical’ production systems controlled with smart products and the far-reaching internet ‘cloud’.
With regard to quality control for the automotive industry, the ‘smart’ factory revolution has brought about changes in manufacturers’ measurement needs. For example, the conventional factory and its incumbent methods are no longer ideal in this new environment.
Increasingly, climate-controlled metrology laboratories are making way for in-line inspection systems that enable quick assessment and prompt corrective action. Single-use measurement tools and template-type productivity tools (eg: check fixtures) are also slowly becoming obsolete. Replacing them are new devices that cater to multiple application needs, and that allow for machine-to-machine collaboration, cloud-based data inspections, and digital engineering processes.
3D Coordinate Technology In The Automotive Industry
For an industry such as automotive manufacturing that carries out high volumes of inspection daily, 3D coordinate measurement is indispensable to its operations. Here are some ways that the technology contributes to better running automotive production in the new manufacturing environment:
1. In-line Inspection
In response to automotive manufacturers’ cost-control needs, metrology suppliers began to develop devices that maximise efficiency, by eliminating the time and effort that manufacturers spent on transporting components to and from measurement rooms.
The portable CMM — a device that provides accurate readings even under the harsh conditions of the shop floor — was born. In essence, inspection checks are being moved closer to the production line, to a point where manufacturers demand the ability to complete tasks without even moving components off the line.
2. Production Part Approval Process (PPAP)
The digital data that 3D coordinate technology provides is useful for manufacturers that practise Production Part Approval Process (PPAP). Regardless of where along the supply chain a component supplier is present, the PPAP industry standard requires that each item of output fulfils design specifications consistently, as spelt out by the client. In that way, the automotive manufacturer is given full assurance of its component suppliers and their production processes.
3D coordinate technology has facilitated the execution of PPAP in the automotive industry today. The speed and consistency in which measurements are acquired by 3D coordinate devices enable both suppliers and manufacturers to communicate their requirements and results clearly and easily.
3. Machine-To-Machine (M2M) Collaboration
In a smart factory environment where machines ‘talk’ to one another, precision and automated inspection are key factors for manufacturers to achieve efficiency. Today, there are 3D measurement devices that provide those capabilities to make M2M collaboration a reality.
4. Highly-Flexible Mass Production
Changes in market demand for non-standard auto parts imply that manufacturers need to possess highly flexible production systems. To cope with varied needs, manufacturers seek out versatile tools that handle multiple applications and flexible part volumes, so as to cater to as many options as possible at the lowest cost.
5. Digital Engineering
With the emergence of this engineering discipline, manufacturers have been able to improve and develop their production processes and output with better accuracy and consistency. Advancements in 3D coordinate technology, in particular point cloud solutions, have caused the trend to escalate further.
6. Big Data, Cloud Computing
Part of the reason which supports the change in the new manufacturing landscape is the growing popularity of cloud computing and big data analytics. The availability of cloud-based applications for 3D coordinate measurements enables data consistency and integrity, allowing resources (eg: software information) to be shared across readily.
Portable 3D Coordinate-Based Metrology Systems
Portable 3D coordinate technology exists in several forms, including point-to-point contact instruments (eg: articulated arms and laser trackers), non-contact laser line scanner and 3D imagers.
Fundamentally, these devices provide the benefits of CMMs with the added versatility of being portable, which allows the user to deploy wherever there is a need. In addition to being less cost-prohibitive than fixed CMMs, portable CMMs do not require a controlled environment, making it easier on the pockets to operate and maintain them.
Point-To-Point Contact Instruments
One of the most common portable CMM devices available is the articulated arm. Equipped with several articulating joints, these measurement arms are able to determine and record the location of a probe in 3D space and report the results through software.
Typically, articulated arms come in models with either six or seven axes of rotation, providing the user with flexibility while performing measurements.
Some articulated arms are capable of providing volumetric accuracies of up to 23 microns (0.023 mm) and weigh about 10 kg (model dependent).
Apart from the articulated arm, another device that performs contact measurement is the laser tracker. Designed to handle larger working volumes, laser trackers offer extremely accurate measurements over long ranges.
Measurement ranges and accuracies have improved significantly in recent years. For instance, the Faro Laser Tracker Vantage’s radial measuring range is 80 m, and at that range, it captures data at typical accuracies of up to 39 microns (0.039 mm).
Non-Contact Laser Line Scanners
As an option, laser line probes can be mounted to articulated arms to provide non-contact scanning capabilities. This technique is a suitable way to create a dense point cloud, which can be used for tasks such as inspection and reverse engineering. Suitable for delicate objects where touch probing should be avoided, non-contact scanning is a quick way to obtain a full surface model of a part.
The device projects a laser line on the part to be inspected, which is reflected back towards the scanner and captured by a camera. Through standard triangulation methods, 3D locations are determined and recorded accordingly. By moving the laser line across the entire surface, the probe captures the 3D profile for further processing.
Designed as a portable solution, the 3D imager is an accurate, non-contact system, capable of capturing surface data of up to four million discrete points in seconds.
The device uses light projection technology and a camera to generate true representations of any part placed in its field-of-view (around 0.5 m x 0.375 m). For larger parts, reference points can be added so that separate sets of point clouds can be stitched together when needed.
Case Study 1: Using 3D Coordinate Technology On EVs
Okayama Vehicle Engineering Center (OVEC), a network of 16 companies from the Okayama prefecture was tasked with building the next Electric Vehicles (EV). Since its inception, the organisation has rolled out its prototype vehicle, known as the OVEC-One.
The development of the EV was based on Mitsubishi Motors Corporation’s Galant Fortis model. To convert it into an EV, unwanted components such as the car engine had to be removed and replaced with other components (eg: inverter, battery, compressor, heater etc.). The challenge was to layout 10 new components of varied sizes and shapes thoughtfully in the available space.
To ensure that all the equipment fits in the space under the hood, the team acquired 3D data of each item with non-contact measurement, using a measurement arm. With the 3D CAD data, the team decided on the layout virtually, checking that the components do not interfere with each other.
When asked about the design process of the equipment layout, Shiro Aikawa, coordinator of OVEC, said: “3D measurement of the various components was necessary as they varied so widely in shape and size. Many of them were hard to measure with a caliper or tape measure. The FaroArm allowed us to efficiently complete the layout of the hood interior in a short period of time.”
Case Study 2: Using 3D Coordinate Technology In Car Assembly
When it comes to car assembly, FAW-Volkswagen Automotive is a company that requires in-line inspection. The company utilises an overhead conveyor to move vehicles around the plant, and regular inspection and alignment checks on the equipment are necessary to ensure optimal performance.
Common areas of interest requiring inspection include anchor points on the cradle support structure, corresponding anchor points on the conveyor trolley, and relative distances between work piece and centre axis. These measurements vary in nature, and range anywhere between 2 to 4 m in length.
Traditionally, the technicians rely on hand tools such as tape measures, gauges, micrometers, and spirit levels to get the job done. However, these traditional methods were not ideal in more ways than one.
“To begin with, accuracy levels achieved are lower with hand tools,” shared Zhou Tingzhi, an engineer from the assembly shop maintenance department. “At times, complex measurements would require several procedures, and these would accumulate large error margins. It would also take us a long time to perform the measurements and calculations manually.”
The company now deploys a 12-ft measurement arm on the maintenance platform, located right next to the assembly line. Whenever a glitch occurs on the production line, the team would use the device to pinpoint the precise problem area before zooming into it. Since then, the company’s inspection and alignment checks on its manufacturing systems have become much more precise and simple.
This, in turn, has kept the plant operating at its best. Mr Zhou revealed: “Now, equipment alignment and inspection of check fixtures can all be done with just one tool. With the FaroArm, we can accomplish our measurement task, which has a volumetric size of 4 m and below, at an accuracy of up to 0.02 mm. We have eliminated the possibility of human error, and greatly increased the precision levels.”
Case Study 3: Large Parts
Finally, when it comes to the inspection of large components, Komatsu uses the Faro Laser Tracker Vantage to inspect parts used to produce mining and construction equipment, large dump trucks and wheel loaders. Since its implementation, the team reduced measurement time for machinery frames from 1.5 days to a day, with an added capability to measure complex features (eg: mounting holes) on a part.
The reason for doing so is because of the sheer size of the parts. It is common for a machinery frame alone to exceed 2 m, which makes inspection both labour-intensive and time-consuming.