With good planning, an organization can use test and inspection as a tool for competitive advantage. The following will illustrate how this works in an automotive environment; however, the concepts easily generalize to any industry.

During product development in many industries, some type of development, or launch, process occurs. One hypothetical, generic model for such a launch process might look like the following:

• Concept
  
• System level
  
• Preliminary design
  
• Critical design
  
• Test readiness
  
• Production readiness
  
• Launch

The design aspects will apply to process design just as much as to product or service design. So, when should testing begin? Some form of testing can begin when there are accurate simulators or prototype hardware and/or software. Testing becomes more formal as the launch of the product nears. Early testing verifies the state of a design, whether process or product.

Types of Tests During Development

A variety of approaches provide reasonable coverage as one attempts to uncover any significant product or process issues. Some of these types of testing include compliance testing to specification requirements; extreme testing to produce product damage as well as characterize the product; combinatorial testing to check all inputs against all outputs; and stochastic, or exploratory, testing to randomize test inputs.

When Does Inspection Begin?

One of the nice things about inspection is that it is typically nondestructive. While a small sample of product under extreme testing is often studied, large quantities and samples of product will need to be inspected. A product or process can be inspected as soon as there is something to look at. During product development, the following can be analyzed:

• Requirements
  
• Design (HW/SW) and schematic reviews
  
• Computer-aided design (CAD) modules
  
• Models
  
• Prototype parts
  
• Review process
  
• Bill of materials (BOM)
  
• Pricing

This list is not exhaustive, but it is suggestive of the types of characteristics one can use during the initial developmental inspections.

Types of Inspection During Development

Enlarge this picture During product development in many industries, some type of development process occurs. One hypothetical, generic model for such a launch process might look like the above. Source: Kim H. Pries and Jon M. Quigley

A bill of materials verification is used to compare the product with the drawings and with the bill itself. This type of inspection is usually tedious; however, we know that a BOM should be better than 98% accurate to support the manufacturing resources planning (MRP) system accurately. Additionally, traceability matrices can be used to verify product or process against the specification. Checklists at any phase of the process ensure that tasks have been completed. One also can inspect design guidance documents for compliance and perform some level of attribute requirements checking.

In the automotive world, the accuracy of machines, processes and employees is studied with gage repeatability and reproducibility (GR&R) inspections. Accurate templates and measuring instruments as well as determining individual impacts on measurements will enhance the performance of a manufacturing process.

Test, Inspection & Evaluation Master Plan Operations (TIEMPO)

Test, Inspection and Evaluation Master Plan Operations (TIEMPO) expand the concept of a test and evaluation master plan by focusing on staged deliveries of which product or process release is a superset of the previous release, and the test and inspection iterations are coordinated with releases. Under this plan, the following inspections can be handled:

• Code reviews
  
• Code releases
  
• Design reviews
  
• Schematic reviews

TIEMPO helps to reduce risk by developing superset releases wherein each subset remains relatively untouched and most defects will reside in the new portion—the previously developed part of the product or process is now a subset and should have already proven to be defect-free. Frequent critical reviews are used to guide design and to find faults. The frequent testing allows for verification evolution by stimulating quality growth and reliability growth. Experience indicates that the following benefits arise from this approach:

• Reduced risk
  
• Identification of early activities to secure quality—even before testing can take place
  
• Test and design release iterations planned—test tools and test processes developed in time to test
  
• Frequent customer access for review of product evolution

One Industry Approach: Automotive/Vehicular

The standard approach in the vehicular industries is the advanced product quality planning (APQP) mode of the Automotive Industry Action Group (AIAG). The components of this approach are the concept, product development, process development, verification and validation, and feedback and corrective action—each with its own set of steps and input and outputs.

Failure Mode Effects Analysis (FMEA)

Enlarge this picture The Production Part Approval Process (PPAP) is used in the automotive industry. Source: Kim H. Pries and Jon M. Quigley, Project Management of Complex and Embedded Systems, Ensuring Product Integrity and Program Quality (Boca Raton, CRC Press, 2008)

Two automotive tools that illustrate the connection between inspection and testing are Design Failure Mode Effects Analysis (DFMEA) and Process Failure Mode Effects Analysis (PFMEA). The tools facilitate critical reviews of either the design or the processes that produce the designed product (production processes). This tool critiques a particular design or process function using failure modes, causes, effects and some estimated values.

The Risk Priority Number (RPN) is the product of estimation of the severity, probability and detection of a particular failure. The higher the RPN, the greater the risk to the product design or process. Recommended actions often are testing actions to determine if the estimates of severity, probability and detection are valid or to determine another way to achieve the function. In any case, the results of the DFMEA or PFMEA have an impact on the design verification testing (DVT) and production validation testing (PVT).

In the automotive world, DVT means using prototype parts, prototype tooling, an unfinished production process and maybe even handmade parts. The purpose of DVT is to test out and verify design ideas before proceeding with development.

Again, in the automotive world, PVT means using production software, production components, production tooling, the final production process and production information systems. The goal of PVT is to verify that product is manufactured correctly using a real production line.

Reliability Testing

Reliability testing assesses the probable quality behavior of the product or process during some quantum of time. During reliability testing, small sample sizes are used when a baseline exists, as well as with larger sample sizes with no baseline. Physical models for accelerated testing are used in order to compute probable product life, which can be hampered by lack of good models, especially when a baseline does not exist.

The Production Part Approval Process (PPAP) and Inspection

APQP supports multiple inspection points such as bill of materials checks against parts and drawings, appearance approval and the various review processes.

By definition, an inspection is a form of quality containment—trapping the product or process that does not truly break the chain of cause and effect. The function of inspection, then, is to capture bad material and to stimulate meaningful corrective actions.

In the automotive approach, there are at least 18 items that must be provided to the customer. The list includes the following:

• Design Records
  
• Authorized Engineering Change
  
• Engineering Approval
  
• DFMEA
  
• Process Flow Diagrama
  
• PFMEA
  
• Control Plan
  
• Measurement System Analysis Studies (MSA)
  
• Dimensional Results
  
• Records of Material / Performance Tests
  
• Initial Process Studies
  
• Qualified Laboratory Documentation
  
• Appearance Approval Report
  
• Sample Production Parts with pictures
  
• Master Sample with signoff
  
• Checking Aids
  
• Customer Specific Requirements
  
• Part Submission Warrant (PSW)

All documents must be inspected before they go out or are reviewed with the supplier quality assurance personnel of the customer organization.

Ensuring Quality

Test and inspection are critical to the successful launch of a new product or a major modification of a previously released product as well as a new process. Both testing and inspection provide for verification and validation that the product and the process are functioning as expected. If all goes well, one can expect a successful launch.