The ideal way to achieve efficient automated testing

Today, automated systems with integrated metrology equipment are widely used in industrial production lines. This article analyzes the limitations of metrology automation, proposes that semi-automated systems are more cost-effective than fully automated systems, and provides some suggestions on when to integrate automated inspection systems in production lines.

Automated production environments are nothing new. Control systems and information technology have reduced the need for human involvement, a fact that has existed for decades. However, integrated metrology equipment is a relatively new concept in the automation paradigm. By integrating quality inspection into the production process, companies can benefit from improved repeatability and increased inspection efficiency in their inspection processes, thereby achieving better process control.

When it comes to automated systems with integrated metrology equipment, it covers a wide range of potential options. Automatic coordinate measuring machines (CMMs), that is, those with direct computer control (DCC), have been widely used. In many cases, automatic CMMs have almost completely replaced manual CMMs. Its measurement process is completely automated by the probe. Therefore, automatic CMMs are an option for automated systems such as process measurement and guided assembly processing. The advantages of using these integrated technologies are lower operating costs, consistent performance, and improved product quality. However, there are still some risks in using these automated systems.

The three-dimensional coordinate measuring machine is measuring the blade clamped on the fixture. Outside the measuring machine cover is the robot responsible for loading and unloading.

Limitations of Automation Systems

While automation systems are becoming increasingly popular, they do have some limitations. Common automated production systems utilize robotic equipment to facilitate the automated handling of parts. In some cases, such as unattended manufacturing, a fully automated production cell with integrated metrology tools is the most efficient solution; however, in most cases, a semi-automated solution that combines automated and manual processes is the most efficient solution. When companies evaluate the advantages of these systems, they need to carefully consider when these systems make sense and when they do not, and what the risks and benefits are. The

most challenging aspects are the technical limitations of implementing these automation projects. It is often not feasible to integrate a high-precision coordinate measuring machine on the shop floor because of vibration and temperature fluctuations. Another limitation may be the cycle time of the production cell. Long cycle times result in the use of semi-automated solutions. For example, it is difficult for a part handling system to determine if the robot only moves four times in an hour. In addition, if a shop cell produces parts faster than the metrology equipment can inspect them, a part buffer may be required to accommodate parts waiting for quality inspection. A

bigger issue that manufacturers may face is part cleanliness—an issue that many people are not aware of. After the parts are machined, some metal chips and oil will remain on their surface. In this state, it is impossible to obtain accurate metrology results for the parts, and repeated measurements will damage the accuracy of the CMM. This is when economic factors come into play. Although many people expect the initial cost to be high, they may ignore all the potential expenses, such as the need for housing and buffers for parts storage; the lack of turnkey software solutions due to the lack of standard communication codes between robots and CMMs; the lack of experienced implementation engineers; and development costs are other factors that must be seriously considered.

To solve the above problems, engineers are actively improving feasible solutions and will customize program middleware for them. The middleware can manage the communication between the CMM and the production environment, so that the activities on the shop floor can be synchronized. When the robot loads and unloads workpieces to the CMM and interfaces with external devices on the CMM (such as part fixtures), the middleware communicates with the workpiece handling system to collect environmental information; it manages and displays all measurement system status and can tell the user whether the measurement is in progress, whether the cycle is controllable, whether the cycle is terminated, or whether the workpiece attribute is good, marginal or unqualified.

Schematic diagram of an automated manufacturing cell with a coordinate measuring machine

Advantages of Semi-Automated Systems

Sometimes, semi-automated systems can be even more cost-effective than fully automated systems. The ultimate goal of any manufacturer is not to fully automate the factory, but to get the most out of the given parameters. A more achievable goal, rather than focusing on automation, is to reduce capital expenditures; for example, a company can efficiently operate two CMMs instead of three. Another cost consideration in choosing between automated and semi-automated workpiece handling/inspection systems is labor. Three

highly paid people can be responsible for programming, operating and maintaining this high-tech system.

Although a semi-automated system may require the intervention of a highly skilled person, it may be the best solution for the application. For example, there are four part trays on a conveyor that are automatically loaded onto the measuring machine. Although a person must clamp the parts onto the conveyor, there is always a part in place for inspection. When the CMM operator walks away for other tasks, the parts are not idle.

How to choose the right one

For companies that are considering integrating inspection systems with automated part loading and unloading systems, the final decision will be based on the details of the application. Some initial considerations include the accuracy required, the complexity of the part, the ability to clean the part prior to inspection, and the preferred technology.