Feature Article : Understanding the Inspection Process
By: Jennifer Stepniowski, Regional Operations Manager Pro QC International
Controlling quality by utilizing product inspections throughout the production cycle reduces sourcing risks and cost. However, to maximize the effectiveness of inspections, an understanding of the process is necessary.
Inspections can be conducted at any point throughout the production process, with the maximum benefit observed when strategically employed at the beginning (first-article), in-process (30% -50% complete) and pre-shipment (100% produced and at least 80% packaged). The idea is to identify, contain and resolve issues as quickly as possible.
A key component and initial step of the inspection process is the development of a comprehensive inspection plan. This documentation outlines the methods and procedures required for conducting the inspections. In addition, it provides necessary product details such as conformance characteristics regarding appearance, workmanship, function, safety and packaging. With this information, check points are outlined that classify potential defects (non conformances) as major, minor or critical. General defect classifications used by Pro QC include:
Critical – Any condition found which poses the possibility of causing injury or harm to, otherwise endangering the life or safety of, the end user of the product or others in the immediate vicinity of its use.
Major – Any condition found adversely affecting the product’s marketability and sale-ability or adversely affecting its required form, fit or function, and which is likely to result in the end user returning it to the source from which is was purchased for replacement or refund.
Minor – Any condition which while possibly less than desirable to the end user of the product, does not adversely affect its required marketability, sale-ability, form, fit or function and is unlikely to result in its return to the source from which it was purchased.
The first activity performed on-site includes quantity verification. Depending on the stage within the production process that the inspection is occurring, this may include raw materials, in-process components, inputs (components) from other sources and/or completed and packaged product. Missed inspections sometimes occur when the supplier fails to meet the requirements for product available to inspect.
The verified quantity is used to determine sampling size for a statistically valid method of selecting random units that represent the quality of the total lot. Pro QC uses ANSI Z1.4 2003 single sampling for typical inspections unless otherwise directed by clients.
Sample sizes are selected for each component identified in the criteria for inspection. Acceptable quality levels, AQLs, are identified for determining an accept or reject result. A general example of a pre-shipment inspection on a lot of 1,000 packaged units might include:
Packaging – Special Level III (13 Units) Drop-testing is often conducted to check the integrity of the unit and/or master carton packaging integrity. In addition, the condition of the cartons and labeling accuracy is evaluated.
Appearance & Workmanship -General Level II (80 Units) Examples of appearance and workmanship usually include making sure samples are free of cosmetic defects such as scratches or dents and that all components and accessories are included.
Function & Performance – Special Level 1 (5 Units) Examples of function and performance might include assembly or electrical testing, as applicable.
Defects are classified and tallied once the samples are inspected. The AQLs provide the information required to determine a result for each inspection component. Using the example above for appearance and workmanship, along with the standard AQLs that Pro QC references unless otherwise indicated, the result would be:
Critical defects – 0.010 One critical defect noted results in a reject result.
Major defects – 2.5 On a sample of 80 units, up to five major defects would be acceptable.
Minor defects – 4.0 On a sample of 80 units, up to seven minor defects would be acceptable.
An inspection can be placed on-hold if an issue is identified that is not clearly stated in the criteria or is otherwise questionable in nature. Pro QC will revert to the client for a final determination.
Once an inspection is complete, detailed reports and photographs are compiled and delivered to the client on our web resident database. The factory is immediately advised of the results so that any necessary rework or other corrective action can begin immediately.
Inspecting product at the source either throughout the production process or prior to shipment has numerous advantages, and through a better understanding of the process, the value of this powerful quality tool is maximized.
You will decide how to best apply these procedures to your products, and your Pro QC Account Manager is there to guide you through the process, suggest options and ensure that your projects are conducted to your specifications, whether you are an experienced QA professional or new to outsourcing.
Contact Pro QC and reduce your sourcing risks and cost for outsourced tooling, components and products.