Successfully Automate Mechanical Testing Systems
Increasing globalization and economic conditions have driven organizations to place a greater focus on productivity and quality. As global competition increases, organizations need to operate more efficiently, produce high-quality products and maximize productivity.
Quality management relates to all areas of business from product design to production and service. Manufacturing companies are investing more money and resources into enhancing technology in an effort to improve quality control and productivity. These companies are benefiting from technology innovation, such as automated testing systems, which increase productivity by having the ability to produce goods faster while maintaining high levels of quality. Companies that do not focus heavily on quality tend to lose both customers and money, which leads to unexpected increases in manufacturing costs, along with poor customer satisfaction.
For many manufacturing companies, materials testing laboratories monitor the quality of the product coming off the manufacturing line. In many cases, manufacturing companies use either their in-house lab, or outsource to a contract testing lab. Mechanical properties for these products, whether it is a raw material or finished part, are characterized using mechanical testing equipment.
Tensile testing is the most common type of mechanical test; other test types include impact, compression, hardness and flexure. The product’s mechanical properties are checked and compared to a standard to determine if it meets the required specification. If not, the processes are adjusted and the product is discarded.
Usually, quality testing is conducted as a part of the manufacturing process. The amount of time it takes to communicate the results from quality tests to the manufacturing managers is critical, as money is lost because of manufacturing downtime and products that fail to meet specifications.
Mechanical testing can be expensive, and often, time consuming, which can lead to bottlenecks within the facility. Most manufacturers are not willing to let production lines run without verification that their products meet certain specifications, particularly those companies that produce high volumes of costly products, such as sheet metal companies.
Effective Quality ManagementFor a quality management program to be effective, large volumes of consistent, accurate test results are required. Technique and precision is crucial for obtaining useful data, so it is important not to rush the test. This is a challenge for most companies because testing is traditionally conducted manually, which proves to be a slow and tedious process. Unfortunately, as test backlogs increase, the pressure associated with delayed production schedules often results with operators rushing through tests and cutting corners to avoid bottlenecks. This is a serious problem that results in poor or invalid data.
In addition to the pressure from delayed production schedules, high degrees of repetitive testing cause fatigue and boredom, leading to operator error. Inconsistencies in how specimens are inserted into grips or how extensometers are attached to specimens lower the integrity of the data-the same is true for dimensional measurement. No matter how slight the inconsistencies are within these processes, it may have a tremendous influence on the data. Poor data may suggest that a product is out of spec when it actually is not, causing the production of that product to be stopped and discarded, which ultimately increases production costs.
On the other hand, the data may suggest that a product is acceptable when it actually does not meet the required specifications. This could pose a serious problem for both the manufacturer and the end user, as the integrity of the product is jeopardized, which could result in possible injuries or lawsuits.
Introducing Automation into Manual WorkflowGage repeatability and reproducibility studies (GR&R) suggest that operator error is the most common source of error when compared to error in testing systems or within specimen variability. In an effort to reduce or eliminate operator error, companies have enhanced their technological capabilities by incorporating fully automated mechanical testing systems into their labs. These automatic systems are designed with an automated specimen-handling feature that increases production throughput, improves quality and work consistency, and increases profitability.
It is important to understand the costs associated with quality control when in the process of justifying an automated specimen handling system. Quality control costs consist of preventative, appraisal and external costs. Preventative costs are incurred before a quality issue is discovered and would include costs such as additional training and other proactive activities. Appraisal costs incur while determining a product’s quality during manufacturing. External costs are the costs associated with a failure of quality control and are uncovered by a customer.
External costs result in the greatest magnitude of loss, as they include production expenses, freight, customer service and, most importantly, a negative impression left with the customer. Automated specimen-handling systems fall within appraisal costs and improve appraisal efficiency and effectiveness. Effective appraisal systems lower preventative and external costs, and are typically far less in magnitude than external costs.
Consistent AccuracyThe success of statistical quality control and process control programs requires the ability to perform consistent and accurate tests in large volumes. This can be achieved with robotic specimen handling and loading, which ensures consistent test control procedures, consistency of hundreds of specimen insertions, and precise data analysis and reporting. In addition, automated measurement of specimen dimension and bar-code reading stations eliminate the tedious, error-prone processes mentioned previously.
Automation systems are available in many configurations that meet the needs of a variety of applications, including metals, plastics and rubbers. Custom systems are available to accommodate the more complex specimen geometries and material types, as well as finished products.
A typical tensile automation system consists of a mechanical testing machine, software, automatic specimen identification and dimension measurement, robotic material handling and a specimen storage system. The operation of a system involves the robot moving specimens from the storage system, through an automatic identification and measurement sequence, and then installs the specimen into the grips. After the sequence is started, the process takes place with no operator involvement. Data is collected, analyzed and reported, while systems communicate directly with existing laboratory information management software. Automated systems are capable of running unattended around the clock.
Despite the significant initial costs associated with the integration of an automated testing system, the long-term benefits of automated systems far outweigh the risk and costs associated with correcting quality issues in the field. Q
Quality OnlineFor more information on mechanical testing, visit www.qualitymag.com to read these articles:
- “Sources of Error in Mechanical Testing Results”
- “Extend the Life of Materials Testing Equipment”
- “Casting Company Opens Its Testing Labs”