Inspection

Inspection is a fundamental activity within Quality Control. It is the process of measuring, examining, testing, or gauging one or more characteristics of a product or service and comparing the results with specified requirements to determine whether conformance is achieved for each characteristic.

Purpose and Role:

• Conformance Verification: The primary purpose is to determine if an item (raw material, component, finished product) meets its established standards or specifications.
• Defect Detection & Sorting: To identify non-conforming items and separate them from conforming ones, preventing defective products from moving forward or reaching the customer.
• Data Generation: Provides information about the level of quality being achieved, types of defects occurring, and process performance, which can be used for feedback and improvement.
• Tool for QC: Inspection provides the data upon which Quality Control decisions and actions are based. It measures quality but doesn't inherently control or improve it.

Objectives of Inspection:

• Distinguish good items/lots from bad ones.
• Detect process drift or changes before too many defects are produced.
• Provide assurance to customers (or internally) that requirements are met.
• Gather information about process capability.
• Prevent defective raw materials from entering production.
• Rate the quality level of products or suppliers.

Types of Inspection (Where/When):

• Receiving Inspection: Checking incoming raw materials and purchased components.
• In-Process Inspection: Checking parts or assemblies at various stages during the production process.
  • Floor Inspection: Inspector goes to the work area.
  • Centralized Inspection: Items brought to an inspection lab.
  • First-Off Inspection: Checking initial output after setup.
• Final Inspection: Checking finished products before they are shipped or sent to inventory.
• Functional Inspection: Testing if the product performs its intended function.
• Pilot Piece Inspection: Inspecting initial units of a new design.

Methods of Inspection (How Many):

• 100% Inspection: Every single unit is inspected.
  • Pros: Theoretically catches all defects (though subject to error). Necessary for critical items.
  • Cons: Expensive, time-consuming, often impractical, can be affected by inspector fatigue/monotony, doesn't prevent defects.
• Sampling Inspection (Acceptance Sampling): A sample is taken from a lot/batch, and the decision to accept or reject the entire lot is based on the inspection results of the sample according to predefined criteria (sampling plan).
  • Pros: Less costly, faster, reduces handling damage, feasible for destructive testing.
  • Cons: Carries risks of making wrong decisions (accepting bad lots - Type II error, or rejecting good lots - Type I error). Requires careful statistical design.

Drawbacks/Limitations of Inspection:

• Costly: Adds cost (labor, equipment, time) without adding direct value to the product.
• Post-Mortem: Typically detects defects after they have already occurred; doesn't prevent them.
• Not Foolproof: Subject to human error (measurement errors, judgment variability, fatigue) even in 100% inspection.
• Doesn't Improve Process: Merely sorts good from bad; doesn't fix the underlying cause of defects.

Indian Example: A garment manufacturing unit in Tiruppur exporting T-shirts likely uses multiple inspection types. Receiving inspection checks fabric quality (color, defects, GSM). In-process inspection occurs after cutting (checking dimensions) and after sewing (checking stitches, seams). Final inspection checks the finished garment for overall appearance, measurements, and defects before packing. They might use sampling inspection for fabric bolts but closer to 100% inspection for critical final checks on export garments to ensure they meet buyer specifications.

Inspection is a necessary component of quality management, but the modern focus is shifting towards process control and defect prevention rather than relying solely on inspection for sorting out problems after they happen.