This issue’s “Connector Basics” topic, explained by George Bedorf of APEX Electrical Interconnection Consultants, is connector manufacturing process validation.
Connectors are made from plastic and metal. The selection of these materials, including metal finishing, along with very precise and detailed mechanical parameters, are described on production drawings and related specifications. Connectors that meet all the specified design requirements are manufactured and tested to validate the connector performance. A test report and product specification provides proof that the design satisfies the customers’ requirements. Often, connector performance problems in customers’ applications are a result of product that was not manufactured to specified design requirements. Manufacturing process validation will reduce the risk that this will occur.
Validation of the manufacturing process demonstrates that the processes have the potential (or capability) to consistently produce products that meet specifications and ensures that product design objectives are achieved throughout the product life cycle. Records of the validation are maintained for future reference.
One approach to process validation has been to perform a “first article inspection.” Parts produced by a production tool, usually contacts from a stamping die or plastic housings from a mold, are measured and the results compared to the production drawings. If the requirements are met, the tool is approved. If not, then the tool is reworked or process parameters are changed until an acceptable part is produced.
Is first article inspection enough to ensure that the process has the potential to produce product that satisfies requirements throughout the product life cycle? While essential to verify that new tools or assembly equipment can produce good product, first article inspection alone does not provide the necessary data to validate that all the components and steps of the manufacturing process will ultimately result in connectors that will consistently meet all requirements. Process validation is performed under actual factory conditions with the processes operated by skilled and knowledgeable operators.
Process validation actually begins early in the engineering phase of new product development. During the engineering/scientific phase of a new product creation, consideration must be given to “design for manufacturing.” Agreement between product design engineers and manufacturing engineers on a design that will meet objectives and can be consistently manufactured is an essential element of risk management during the product design and development process. If risk assessment determines that the necessary manufacturing technologies have not yet been sufficiently developed and tested, then a manufacturing process development project should be completed before proceeding with the proposed design.
A competent product development engineer will understand the manufacturing processes and tooling to the extent that most design requirements will be easily met by the manufacturing process. Teamwork between product development and manufacturing engineers will identify dimensions and characteristics that are critical to function or critical to quality as well as those dimensions and characteristics that are indicative of process stability. These critical characteristics will be agreed upon prior to both the design FMEA (failure mode and effects analysis) and the process FMEA. The FMEAs will verify the critical characteristics. The critical dimensions are related to the function of the design feature but not to the tolerance limits of the dimension.
Using the product drawings, critical dimensions, and characteristics, as well as the production capacity requirements and cost objectives, the manufacturing engineers will develop requirement specifications for all tools and assembly equipment that will be part of the manufacturing process. These requirement specifications will also include tool and process verifications that are necessary to approve the tools and equipment for delivery to the production location. In addition, manufacturing throughput and cost-related targets are established.
Based upon this information, the team develops a plan for manufacturing process validation. The validation plan should include capability studies for the identified critical dimensions. These capability studies will also include an analysis of the capability of the measuring instruments. Where 100% automated measuring and inspection is part of the manufacturing process, the validation confirms that these devices accept only product that meets requirements. The quantities of components and assemblies needed for the validation tests should be documented as part of the plan. Data collection forms are also developed for maintenance of records.
When the production tools and equipment have been installed at the production location, sufficient material should be used to establish the process parameters for each step of the process. Also, any required training will be provided to the production process operators at this point.
Next, a formal process and product control plan must be documented. This is a concise summary of process parameters and product dimensions and characteristics that will be measured and monitored during the production process. Any needed measurement capability analysis should have also been completed.
When both the manufacturing and product development engineers have objective data that demonstrates all tools and equipment are production-ready, process validation may start.
Typically an engineer from the manufacturing organization will coordinate validation activities between the various production locations, including suppliers. This coordination includes more than completing paperwork and sending it along with product to the next process location. The responsible engineer must ensure that the process parameters are kept constant for each step of the production process and that operators are not “tinkering” with the process parameters. It also is essential that all material be identified for traceability of material and that samples used for monitoring and measurement are kept with the data.
At the end of the process validation, a report that summarizes the results is prepared and reviewed by members of the product development team. This report will validate that in addition to product quality requirements, requirements for manufacturing costs and volumes can consistently be achieved. What happens if the results of the testing do not validate that all objectives can be met in production?
It is important to note that the risk of not meeting objectives was mitigated by informed selection of the critical-to-function and critical-to-quality dimensions, thorough tool and equipment requirement specifications, and testing of all tools and equipment prior to delivery to the production facilities. Therefore, any shortfall in meeting objectives will be relatively minor and may be resolved by the development team with small changes and then repeating a part of the validation testing. If in the interim it is necessary to produce product for sale, the control plan must be modified such that all product delivered to customers will fulfill all design objectives.
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With more than 30 years in the connector industry, George Bedorf has established a record of success with strategic planning and tactical implementation using process improvement methodology. He has expertise in the use of planning and tools to improve both business and manufacturing processes, as well as extensive hands-on experience in the development and implementation of new processes and the introduction of new products into manufacturing. Bedorf’s management experience includes director of quality assurance at AMP Incorporated. He has an engineering degree from Stevens Institute of Technology.