Inspection & Sorting: At What Cost?

The cost of inspection is an ongoing issue between the automotive companies and fastener manufacturers today. As the automotive fastener manufacturers work to reduce price by means of improving the efficiency of the manufacturing process, their inspection costs have risen dramatically.

Historically, fastener manufacturers have focused on manufacturing parts, with sorting as an afterthought. Now, because of the quality demands placed on them, the sorting departments are growing fast. This growth has created new variables for the manufacturer, including cost, time, and many times inferior inspection processes.

Are possibilities for reducing costs the same in the inspection area as they are in the production area? Yes, however they are not as easily identified as in the production area. Although the automotive industry recognizes the cost in the inspection of the manufacturer's product, they aren't willing to pay higher prices to reduce suppliers' PPM levels. Suppliers can not always include inspection costs into the piece price, especially on grandfathered parts. Regardless, the expectations from the automotive industry still remain at zero PPM levels. And, in most cases, the fastener manufacturer has to incur the inspection cost.

Inspection departments today incorporate a variety of different methods to provide what is called 100% inspection. Methods that include hand sorting, roll sorting, acoustic, inductors, vision, and single laser inspection all reduce PPM levels to some degree. The remaining defects which make it through these methods cause the manufacturer additional costs which should not be overlooked. These include chasing problems in the field, flying personnel to customer's plants to resolve issues, hiring outside sorting companies to manually inspect product on the line, air freighting replacement parts, customer visits, 8-D's, and the potential loss of business due to reputation. When you add these costs along with any original equipment investment, the cost of sending product out or buying superior equipment is no longer expensive. Another potential cost is the automotive industries' back charges for assembly line shutdowns due to defective parts. This is becoming more common everyday and impossible to factor into a business plan. Line shutdown costs can be enormous, and will cripple the bottom line.

Mectron Engineering Company, Saline, MI, is tackling the 100% inspection issues from two sides. One is to supply proven inspection systems to the manufacturing companies to inspect their own product. The other is to use its own equipment to provide a high volume, automated inspection service.

State-of-the-Art Sorting Facility

Some companies have taken the human element out of sorting, and run their products through inspection machines. However, where they still have issues is in the packaging of the product after it has been inspected. It makes no sense to run product through an automated machine, only to have foreign material introduced at a separate packaging operation. The way to run the inspection department is to inspect and package in the same operation. The right way is through the machine, into the box, seal the box, and place it on the pallet. Mectron has perfected the turnkey sorting system to provide customers with 100% inspected — zero defect product.

Mectron Engineering Company is the only company in North America that utilizes its own machines and technology to sort and inspect products to zero defect levels. With quantities exceeding 280 million pieces annually, Mectron has a documented PPM level of a remarkable 0.000000012! (Figure 1). Since its inception, Mectron has sorted and inspected nearly one billion fasteners to this PPM level. This is the PPM level manufacturers can expect to achieve upon implementing a turnkey sorting, inspecting and packaging system.

Figure 1

The key to this success is Mectron's patented laser technology. By slicing the part into 16 points of inspection around 360° of the entire length of the fastener, the Mectron Q4000 (Figure 2) provides the most complete measurement capability of any system on the market today. Along with the addition of Magnetic Imagery™ for metallurgical defect detection (Figure 3), fasteners are inspected for both dimensional and metallurgical defects. The Q4000 is the only system used in Mectron's sorting facility. Most manufacturers have collected a variety of different types of inspection systems that allow them to reduce PPM levels, but, based on their capabilities, they also have to absorb the associated costs by not achieving zero defects.

Mectron has been focusing only on the business of inspection. Along with the patented laser technology, Mectron has developed an ISO 9002 certified program that eliminates the breakdowns that typically are associated with sorting departments. A full ISO compliant package can be supplied to Mectron customers to aid them in setting-up an inspection department (work instructions, process flow diagrams, preventative maintenance, etc.). Maintaining process flow through the inspection department is critical in order to maintain zero defect levels.

The advantages that Mectron inspection services provide are directly transferred to the manufacturing community. By feeding and packaging millions of fasteners annually, the intricacies of handling and controlling large variations of manufacturers' products can be fine-tuned and perfected. Mectron's entire system is continuously undergoing improvement, such as material handling, proper part separation, programming and controlling the product through the accept/reject gate. With this experience, Mectron has been able to eliminate potential catch points and areas that could cause damage. Mectron's own in-house sorting department enables them to test new technologies and software upgrades in a controlled atmosphere. This past experience allows Mectron to supply systems that hit the floor running.

Customer Driven Evolution

Continuous improvements in machine design, laser implementation and software modifications have all been driven by specific customer applications. Many existing Mectron users of the original 6 laser machines are opting for an 8 laser upgrade. The need for more inspection points around the part is becoming more important due to automotive demands. The tolerable defect size shrinks by the week, and the 8 laser Qualifier® provides the most complete on-the-fly inspection. Comparisons of 6 and 8 laser layouts and their respective defect detection heights can be seen in Figures 4 through 7.

Software advances are resulting in amazing defect detection capabilities. Previously difficult to inspect defects such as turned hexes on a round flanged part are now inspected quickly and easily on the fly. The laser array provides a relationship from laser to laser that allows for accurate measurement of flats and corners on the hex. The difference of the measurements from one laser to the next provides data to a new software feature that interprets these numbers and calculates the differences between a good hex and a good flat. Another technique in utilizing existing laser technology has allowed Mectron to provide bent part sorting on the Qualifier® machines with minor modifications. These are just a small sampling of R&D innovations driven by the needs of the fastener manufacturers.

Where Do We Go From Here?

Partial elimination of problems is not adequate in today's market. Costs involved with shipping defective product are escalating daily. In the long run, economically, it makes sense to go with a product or service that produces ultimate cost savings (which means zero PPM's) to both the fastener manufacturer and the auto producer.