Circuit board and semiconductor device technology has increased to the point where manual operations in component insertion, soldering, and test have become increasingly difficult for the assembly line worker. Even with good work instructions, errors often do occur and are not identified until a rework and repair operation is necessary. Some test operations on circuits that contain software are prohibitively time consuming when performed manually. Unfortunately, the production rates on military hardware, such as missiles and tactical computers, often are not considered sufficient to justify the introduction of automatic assembly equipment. Therefore, we remain content with manufacturing state-of-the-art electronics using the processes and procedures that are obsolete. Production rate should be a basis for determining the degree of factory automation; but is not an excuse for not taking the steps necessary to ensure efficient product manufacture.
Changes on the factory floor are often considered as discrete, isolated events that only impact the assembly line worker. With the introduction of any assembly aid or semi-automated equipment, consideration must be given to the other plant operations that are likely to have an increased workload. For example, consider a plant operation that introduces a fully automated production line but has not considered upgrading the materials and yield tracking capability from a manual method of operation. In such a case, it will not take long for spot material shortages to appear and the availability of yield information will be obsolete before it can effectively be used. The result should be obvious! Any anticipated gain in productivity, reduced production costs, or improved production rate will not be achieved. In fact, it may appear that it was more cost-effective to fabricate electronic assemblies using manual techniques.
The type of facility involved in the manufacture of the end item product should be consistent with an accurate assessment of current manufacturing operations, the ability to perform the job, the knowledge and implementation of technology improvement projects (along with the necessary capital investments), and the necessity to reduce production costs and sustain production efficiency and product quality.
On low rate production lines, assembly aids for manual component insertion, the use of optical comparators for visual inspection of circuit cards, and programmable cable assembly equipment is cost-effective. A semi-automated transport system that provides controlled material flow for peak production efficiency also should be used.
The decision to introduce automated insertion equipment should be based on the anticipated production rate for a family of product types. Cost analysis comparing manual operations to the use of semi-automated equipment should be conducted using the number of component insertions per month for the family of product types. The results of the cost tradeoff should be a predominant factor in the decision to use automated insertion equipment.
Some degree of programmable test equipment is critical to the efficient testing of today's electronics circuit cards and assemblies. As a minimum, in-circuit test equipment that verifies the integrity of circuit assemblies before soldering, and programmable functional test equipment should be evident.
As assembly aids and automation are introduced on the factory floor, other areas for facilities improvement should be considered. For example, a material and process control system can accurately provide for the location of the components within the plant, the status of the operations completed on subassemblies currently "in-process," and routing directions for the balance of the process. Methods based on a manual process prohibit timely responses to project changes, inhibit different functional areas from accomplishing more discrete and finite scheduling tasks, and above all, cause excessive schedule delays within the manufacturing cycle.
Utilization of computers to support manufacturing processes, using a common design and manufacturing database should be considered as facilities improvements are made. Also, computer graphics capability can reduce the drafting tasks by 10 to 40 percent over the standard drafting board approach with the added advantage of enhanced accuracy and quality.
Current blueprint control systems are another candidate for computer assistance. Manual blueprint control systems require considerable lead time. Drawing revisions take too long because the system is technically antiquated resulting in operators using obsolete information. On-line computer access at key operator stations affords the capability of working with the latest drawing revisions. Many delays in completion of product fabrication can be attributed to the complexity of the planning paper that must travel with it. Using computerized technology can reduce the typical factory paper work such as planning sheets, routing sheets, work loaders, assembly instructions, and quality control documents.
Automated test and tracking techniques should be developed as part of the facilities improvement effort. Such test and tracking techniques can monitor where key parts are located through the manufacturing process and provide a real-time status of work-in-process assemblies. It can record test results and perform statistical tolerance analysis. Tracking techniques also provide for the location and progress of the processed item against the commitment baseline.