Components can be a large part of the raw materials costs that go into building a circuit board. Diligently managing the purchasing process ensures the best possible part at the lowest possible price, and today's MRP systems provide the pathways from driving demand to purchasing to receiving and delivery of goods to stock.
Pick lists give an orderly method of kitting parts against production orders. Companies control inventory at every step of the path — from the back door to the manufacturing line. But in many operations, the trail turns cold at this point.
A good start is to implement a concise, complete tracking system that picks up where normal MRP systems end — as components are kitted for assembly.
Minimal changes to the existing process can ensure end-to-end inventory tracking. Adding a bar code tag to incoming reels and tubes enhances the normal matching of packing slip against the original order. The bar code ties the vendor, vendor lot code, quantity, part number and type to a centralized database.
At this point, inventory and stock room clerks can scan the bar code to identify inventory movement from the dock to the stockroom and finally to the assembly line. Scans performed at each stage provide positive tracking of all inventory movements.
As components are pulled from the kit and loaded into intelligent feeders, another scan links the two pieces of data. The specific intelligent feeder is loaded with the complete tracking information for each job, including available inventory. Once loaded, the feeder is mounted on a docking feeder cart and ready for the changeover process.
Reducing changeover time and supply-uncertainty headaches delivers an important benefit to managing your resources. Intelligent feeders are an ideal complement to docking feeder carts in your capital equipment strategy. While the actual savings depend largely on the previous waste rate and set-up yields, it can be a significant figure.
Rapid Changeover Time
Using intelligent feeders brings extended benefits; specifically it allows materials personnel to manage materials and production personnel to focus on production. Materials personnel will load component information — vendor, lot code, component type and quantity — directly to the inventory control system. Once the part is married to a tape feeder in the production area, the information can now be shared with the all placement systems and the host database server. As loaded feeders are moved around the production area to various machines or docking carts, data integrity is maintained.
The intelligent feeders provide the ability to track component lots and consumed and remaining inventory. This eliminates guessing about how many components are left on a reel, provided no "strips" of tape are removed manually. This practice will cause both a loss of traceability and inaccurate inventory counts, defeating some of the key benefits if the intelligent system.
One additional feature of the system is production prediction, where the system knows how many boards can be produced with the current load, and what the first shortages will be. This makes it possible for the production manager to decide when the low supply indicator illuminates to give operators time to either splice another reel onto the feeder or replace the unit with a new supply of parts before a work stoppage can happen.
When it's time to change over the line, exchanging docking feeder carts takes an average of a few minutes per side. Since the carts are pre-verified off-line, they will be ready to run; however the intelligent feeders log on to the placer control system as soon as they are connected for verification. A row of green indicator lights lets the operator know the process is complete and all the proper components have been loaded onto the system. Any other indicator color — yellow or red — lets the operators know that additional attention is required.
Utilizing a system designed-in by the equipment manufacturer allows for a more proactive approach and ensures maximum efficiency and yields. Taking advantage of the feeders' built-in intelligence, docking cart verification system and integrated lot-tracking system maximizes profitability by reducing and, at times, actually eliminating waste.
Changeover Process Verification
Intelligent feeders can enhance verification of the overall rapid changeover process with first article inspection. Quality control checks determine how this inspection is performed. In some cases, it's a simple visual check of paste deposition and a verification that all components are on the pads correctly. In other cases, first article inspection could include automated machine vision verification of paste and placements. Some manufacturers may continue to build a short run of boards during the first article inspection phase, making any necessary adjustments prior to the reflow process.
A successful rapid changeover can be completed in 10 to 15 minutes, depending on the complexity of the line, operator skill and first article inspection requirements.
With the SMT line changeover completed, the feeders help keep the line running efficiently with their on-board inventory report. Indicator lights change from green to yellow as the line reaches the pre-set inventory replenishment threshold. This gives operators sufficient time to replenish the supply, either by splicing in a new reel or preparing to replace the feeder once it uses the last part. Regardless of the method used, production can continue uninterrupted by unplanned downtime. Managers can set the low-parts warning threshold based on the ability of the line operators to respond to the alert.
Complete tracking information is available once production is completed, providing detailed reports on parts usage. Reports can follow the production lot or be included in serialized board records.
Reaping the Benefits
Making small changes in handling components within the production process can significantly reduce planned and unplanned downtime on the SMT line. Using tools such as docking feeder carts, intelligent feeders and the information they supply to manage component inventory contribute to making an SMT line run more efficiently. Reducing changeover time by preparing docking carts with intelligent feeders in the stock room or prep area can both increase production efficiency and add a degree of management certainty that can be reflected in better cost management and reliable delivery schedules. Intelligent feeders can help manufacturers work smarter and increase their bottom line.
Contact: Samsung/Dynatech Technology, Inc., 1 Rodeo Drive, Edgewood NY 11717 631-667-4910 E-mail: info@DynatechSMT.com Web: http://www.DynatechSMT.com