Here is a list of abbreviations used in this report.
- TE: Test Executive – manages the execution of a sequence of test steps.
- COTS: Commercial Off the Shelf – describes components that are readily available around the world.
- BDB: Business Database – developed or maintained by the manufacturer to assist in workflow and tracking of purchased inventory and manufactured goods.
- BOM: Bill of Material
- TDB: Test Database – holds test results from all tested parts and is used for both statistical analysis or test data as well as interfaces with the BDB to manage the workflow of the part as it moves through the assembly processes.
- OEE: Overall Equipment Effectiveness – measure of the usage and functionality of a piece of equipment.
- WIP: Work in Process – a measure or list of manufactured goods in an incomplete state of production awaiting final manufacture.
- MRP: Manufacturing Resource Planning – method or tool for planning the manufacture of goods including inventory, tooling, financial, personnel, and other resources needed to build and assemble the products.
Companies dealing with low-volume production often consider test automation to be cost prohibitive. Tests are typically done manually with minimal or no automation. And, measurement records are put on paper or into a secluded data file.
Automated test platforms running COTS test executives are often designed for high-volume production and don’t meet the needs of the situations of manual and semi-automated testing. Furthermore, low-volume production is often correlated with a need for strict control over measurement records because regulations or liability concerns put high value on the ability to retrieve the measurements recorded from a specific part long after it has been sent to the customer. Finally, because test results produced by these manual or partially automated test platforms are often less accessible, opportunities to improve the production process can be missed.
The solution discussed here reviews an approach that has shown quantifiable improvements at many test system installations by connecting test equipment with business systems to manage electronic work instructions, test procedures, and test records used by manual or semi-automated test systems.
While the discussion necessarily remains high-level due to confidentiality restrictions with most of our clients, we are able to report the specific results from one client that has agreed to share important performance metrics. This client is a manufacturer of low-volume and high-mix aircraft and space electronics and avionics, and will be referenced as the Aerospace client.
Many of our high-mix and low-volume clients had previously managed production by traditional means, with paperwork assigned to each production unit and operators performing inspection of the unit as it was assembled manually. Manufacturing assessment was made by manual weekly tally of production volume at each assembly station and issues encountered during assembly.
Because of the high-mix production environment, multiple whiteboards filled with production status were often scattered around the production floor to help management address critical issues. Significant labor was involved in maintaining and assessing current information on these whiteboards. Furthermore, written material was almost everywhere. Assembly work instructions and resulting test data were written on paper that traveled with each unit. As tests were performed, resulting measurement data was recorded manually, often on paper. The chance for error was significant. When questions arose about the status of a particular unit, many hours could be spent in locating and evaluating the paperwork.
By integrating the business database (BDB) with a test executive (TE) and a test results database (TDB), manufacturers have been able to reduce production costs. Specifically, the Aerospace client saw an average of 30% cost reduction across many product lines.
The automation of transactions between a TE, a TDB, and the BDB greatly enriches the ability of a manufacturer to improve both the manufacturing process flow and part quality.
The payback on the development cost for this type of integration depends strongly on the number of different product groups that are supported because this count is almost linear with the level of development effort. But, also important, is the amount of effort to create and make accessible queries that the TE and TDB can use to access the BDB.
For our Aerospace client, the payback was estimated to be about 1.5 years. Furthermore, installation time for upgraded test stations is typically between 1 to 4 weeks, depending on the complexity of the part being tested. Table 1 shows efficiency gains in various areas of manufacturing management. These gains total to about 30%.
Table 1 – Efficiency gains from various tools
In addition to the gains in management efficiencies, production gains are possible because, with test and assembly results placed in the databases, managers can perform statistical analysis of production bottlenecks and identify the most effective corrective actions at the business level. Management of subassembly BOMs and assembly instructions, with associated test steps and results, offer a clear understanding of manufacturing improvement opportunities. Specifically, our Aerospace client now manages seven times the production volume as 10 years ago without significant increase in production personnel.
Without the rapid access to the test and assembly data provided by these automated database transactions, manufacturers were previously wasting significant time locating status information or identifying problem areas. Worse, some production problems were never addressed due to the attention required by the immediate “fire fight” of the day.
Furthermore, mistakes and wasted time during assembly were avoided by assuring that assembly instructions were the correct version. Previously, significant effort was needed to assure that up-to-date instructions were in the hands of the assembly personnel. By placing work instructions in electronic documents, we are able to assure that the operator(s) at the assembly and test station(s) use the proper version of the work instructions. These work instructions are tied to part and model numbers so that reworked parts use the associated version, even if that part was several revisions behind the present.
Assembly errors were reduced and traceability was improved, leading to accolades from the customers of the manufacturers.