Feature Article : What You Should Know About QC Product Inspections
“The ideas of control and improvement are often confused with one another. That is because quality control and quality improvement are inseparable.” ~Ishihara
Why should you perform QC inspections?
A benefit associated with ensuring product quality through QC inspections includes identification of problems early in the process with the goal of eliminating the cause(s). In addition, inspections can reduce costly rework, warranty costs, etc. And, they can avoid shipment delays and provide valuable data useful for effective supplier management.
Most importantly, QC inspections ensure product meets your customers’ expectations. Many times, our clients don’t see the product before it reaches their customers. This makes an on-site evaluation even more of a significant advantage as an added level of assurance.
Who should perform product QC inspections?
It is often costly to allocate internal resources to inspection activities due to time and travel cost considerations. For organizations using an agent and/or trading company, they may not have specialized QC resources and often represent multiple interests. A manufacturer may have QC incorporated into the process, but it does not offer an unbiased evaluation. Using a third-party such as Pro QC allows organizations to partner with experienced, knowledgeable quality professionals that have local expertise and can offer a non-biased evaluation at a reasonable cost.
What happens during an on-site inspection?
Pro QC’s quality engineers are deployed to locations worldwide. A standard inspection would incorporate the following:
The engineers will use a checklist designed with the specific product specifications and other characteristics/criteria in mind. Random sampling and AQLs are generally ANSI Z1.4 based but can vary depending on the industry requirements or client request.
QC inspections can occur at multiple locations. Most often, product inspections occur at the manufacturing facility. However, it is not uncommon to inspect at a warehouse, fulfillment and/or distribution center.
When is the best time to perform inspections?
Pre-Production (First Article)
The pre-production inspection is considered essential in the process of approving the parts/components/products.
The purpose of this inspection is to determine objective evidence that all engineering, designs and specification requirements are clearly understood, accounted for, verified and recorded. This includes a complete, independent and documented physical and functional inspection process to verify that prescribed production methods have produced acceptable items as specified by engineering drawings, purchase order, engineering specifications, and /or other applicable design documents.
An in-process inspection is performed to monitor that the established production methodology and techniques are being followed, and to verify manufacturing process can flow smoothly towards meeting the product’s engineering specifications requirements and reliability.
In this stage of inspection, each process is verified and recorded for early detection of errors and deficiency in the process that might lead to a product’s nonconformity. This allows for corrections enabling the product to continue its flow through the manufacturing process. An in-process inspection is conducted when 20% - 40% of the products are produced.
This is a reliable quality control method for checking the product’s quality throughout the relationship with the supplier. The pre-shipment inspection happens when the products are 100% produced and 80% packaged.
This inspection is to be carried out under the industry sampling standard, the ANSI / ASQ Z1.4-2008 TABLE I for Single Normal Sampling Plan, Doubling Sampling Plan, Tightened Sampling Plan and Reduced Sampling Plan methods or any sampling plan methodology to be given by the client. The sample size will be determined from the sampling plan based on the shipping lot and will be randomly selected from the submitted shipping lot. You can view the ANSI Z1.4 sampling tables here. (http://proqc.com/quality-resources/ansi-sampling-tables)
Pro QC also assists with inspections of reworked items or other special requests as required.
How often should you inspect?
How often to inspect depends on a number of variables:
Supplier history (new supplier vs existing)
Product return information
Internal evaluation feedback
Size of purchase order
Legal agreements (requirements)
How do you use defect data to drive improvements?
Inspection reporting information can be useful in identifying trends in supplier performance. For example, consistent defects in one area may warrant a process audit to identify the root cause and employ corrective action for resolution.
Using inspection data:
Evaluate a check sheet or other data chart over a period of time.
Visualize the information to observe and compare trends over any determined period of time.
Incorporate multiple suppliers to target improvement efforts at each location. For example, is one supplier exceeding at meeting expectations in one or more areas where others are not? Why? Use quality tools to further examine root causes and execute corrective actions.