In commercial truck production – where vehicles are manufactured with thousands of components produced by several suppliers from different countries around the world – major components require record keeping, and traceability is key. Traceability, the capability of tracking goods along the supply chain, provides real-time information on where, how, and by whom parts are produced and integrated. Such an approach provides means of reducing, controlling, or eliminating recalls during production processes.
An example of traceability challenge is Jacobs Vehicle Systems Inc. in Bloomfield, Connecticut, a manufacturer of diesel and natural gas engine retarding systems and valve actuation mechanisms. To support a request from one of their largest customers for improved traceability, Jacobs was faced with the requirement to add scannable, laser-marked traceability content to the brake rocker arm during manufacturing and assembly.
Just before final assembly, the rocker arm is tagged with a data matrix code – a 2D computer code that includes basic components and manufacturing information – and a human readable content. One key requirement was that the data matrix had to be validated on 100% of the parts and pass a C or higher grade for it to be acceptable. Additionally, the cycle time had to be held within 25 seconds. The 2D code grading process guarantees traceability of the applied mark throughout the assembly process and throughout the lifetime of the product.
On a different customer’s rocker arms, products are marked and validated in a two-step process. First, the operator loads the part in the laser marker; the part is then placed in a nearby vision grading unit that verifies the 2D code grade. Because of this additional step, the process adds another 10 seconds, impacting productivity. Moving to a fully automated solution would improve cycle time, guarantying 100% verification. This option was very attractive for Jacobs.
Fast, automated part validation
After the evaluation of possible technologies to improve performance and cycle time, Jacobs opted for the laser marking capabilities of Foba because of its Intelligent Mark Positioning (IMP) technology. Foba lasers provided some clear advantages to the manufacturing requirement of the commercial truck industry.
Brent Mayerson, manufacturing process control engineer at Jacobs, comments, “The fact that that Foba could do 100% in-system validation eliminated the need for a separate machine. Saving space and operator time were key benefits.”
The ability to validate the data matrix code right after the part has been marked, without the need for an operator to handle the part, eliminates extra handling that directly affects cycle time. The validation process consists not only in grading of the 2D code, but also in validating its unique content, something that would not have been possible on a remote station without adding a tracking process and networked devices. On the new line, the complete grading process added less than one second to the full 20-second process, a significant improvement compared to the other line’s two-step operation. The recorded information, which include date, time, production information, and passing code, is available for storage on a network drive or the cloud and can be used to manage customer inquiries.
Improved laser marking technology
With the evolution of lean manufacturing, suppliers are continuously challenged to find solutions that minimize manufacturing risks, improving yield and throughput while tracking processes in real-time. Traceability of parts and record keeping of manufactured components have evolved from the human readable mechanical recording such as dot peen (micro-percussion created by a hard needle) to state of the art non-contact technology such as lasers. Lasers have opened the doors to faster and more complex marking solutions, like gray scale marking, annealing, engraving, or layer removal. With today’s technology, digital tracking of production processes has evolved and made many tasks easier.
The use of semiconductors and fiber optics in lasers has enabled marking/engraving systems to come in smaller packages that now can sit on the user’s desktop. They are rugged, air-cooled, run on standard power outlets, require close to zero maintenance, and will outlast compact fluorescent, low consumption kitchen light bulbs. Today’s lasers are easier to use, and come with improved mark accuracy, stability, and performance. Combined with their lower costs of production, lasers have achieve a strong market penetration.
Motor vehicle part manufacturers are continuously pushing for further ways of reducing costs of production. Manufacturing space comes at a premium, and manufacturers are always looking at ways of packing more performance and production capabilities within a smaller footprint. Ever-smaller laser markers have to be able to produce marks on a variety of materials from metal alloys to plastics with a higher mark contrast that lasts beyond the life of the product. Traceability content has to fit in tight spaces and needs to meet their customers’ requirements.
Traceability content typically combines a 2D symbol such as a data matrix code, human readable content, and a logo. Data matrix codes are preferred for their ability to efficiently pack information and are readable even when faced with degradation or contamination.
Marking 2D codes come with sets of challenges as many manufacturers require them to meet a certain standard, typically the Association for Automatic Identification/Direct Part Marking (AIM/DIM) standard. The AIM/DPM standard focuses on methods to grade the quality of a data matrix code using characteristics such as the contrast and the uniformity of the mark.
Marking products for traceability
Finding room on a product to place traceability content is often a challenge. Manufacturers and designers tend to use every available space on the part to squeeze all tracking information required. The marked content, such as the lot number, serial numbers, and a 2D code have to be readable by machines and humans. Sizing down the content is not always desirable, particularly with data matrix codes that require some minimum size as they need to be read by most commercial readers.
As an example, a 2D Code with up to 31 characters will end up with a matrix of 20x20 cells. So it can be read from a distance of 150mm (6") by most readers, it will require and area of 13mm2 x 13mm2 (0.5in2 x 0.5 in2). The space available for traceability content is limited, and the mark needs to fit tight within that space.
With limited space, the alignment of the mark can be a challenge as some of it may not fully land on the part. These slip-ups can look innocuous but could have a direct negative impact on the product’s workmanship. To address these challenges, Foba’s IMP technology has built-in validation tools, tools that validate the part identity and automatically align the traceability content to the part. Often, parts from the same family, that can only be differentiated by a hole size or a part length, are easily confused by operators. Validating the part identity adds a layer of safety that prevents the wrong part from being laser marked. The mark alignment feature, on the other hand, compensates for those situations where the part is not properly seated in its fixture and aligns the mark to the part.
Another benefit of using laser systems with built-in traceability capabilities is their ability to be reprogrammed on the fly. Stand-alone, dedicated, industrial vision-based validation systems are not always cost effective. A stand-alone code validation station requires mechanical support structures, electrical wiring, lighting, vision programming, software communication, hardware interface, and data logging. The cost of integrating such a system can easily exceed the cost of a laser built-in tool without the flexibility and turnkey solution of a fully integrated system. Stand-alone systems are typically dedicated to a single product and work well as long as a new or a variation of the product is not introduced. In these situations where changes are needed, production is faced with a fixed transition schedule, forced downtime, and strict implementation schedules.
The implementation of the proper traceability process is a win-win situation for all – designers, suppliers, manufacturers, and consumers. The reality is that the commercial truck industry is in constant evolution. With manufacturers managing parts coming from different suppliers around the world, in case of a recall, tracking without a traceability system would be a horrendous if not impossible job.
Traceability plays a key role not only in managing recall efficiently but most important in preventing them as it is used during the entire production process. For traceability to work, recorded contents, either done by a laser or other form has to be properly accomplished. Today’s laser marking technologies are fast and cost effective. Combined with integrated vision, the technology provides a real-time validation and tracking system that helps reduce cycle times, improve quality, and optimize the supply chain by providing information about component movements. Traceability is a key competitive advantage that resonates with higher quality standard and corporate responsibility.
About the author: Faycal Benayad-Cherif is business manager for software and vision at Foba Laser. He can be reached at 978.263.9560 or firstname.lastname@example.org.