Inspection techniques

What is this method?

Visual Inspection is particularly effective detecting macroscopic flaws, such as poor welds. Many welding flaws are macroscopic: crater cracking, undercutting, slag inclusion, incomplete penetration welds, and Essentially, visual inspection should be performed the way that one would inspect a new car prior to delivery, etc. Bad welds or joints, missing fasteners or components, poor fits, wrong dimensions, improper surface finish, delamination’s in coatings, large cracks, cavities, dents, inadequate size, wrong parts, lack of code approval stamps and similar proofs of testing.

Why is this method?
  1. To collect information regarding the performance of the product with established standards for the use of engineering production, purchasing and quality control etc.
  2. To sort out poor quality of manufactured product and thus to maintain standards.
  3. To establish and increase the reputation by protecting customers from receiving poor quality products.
  4. Detect source of weakness and failure in the finished products and thus check the work of designer.
When is this method used?

Many studies across all industries have demonstrated that there is a cost and time ratio for development: production: delivery of 1:10:100. It means each error will cost 10 times more (in dollars and in time) to fix in production than it would to fix in development, and 100 times more if the error reaches the customer.

That’s why checking quality only at the end of production is very risky. But you don’t have to wait until everything is done.

There are mainly three tools at the disposal of buyers, to check on the quality of their suppliers’ products. Each buyer should try to choose the solution(s) that best fit(s) her needs.

  1. Pre-production inspection (a.k.a. “initial production inspection”)
  2. During production inspection (a.k.a. “in-line” or “in-process” inspection)
  3. Final random inspection (a.k.a. “pre-shipment inspection”)
Roles and responsibilities:

The quality inspector usually follows a pre-established checklist that is based on the product specifications. Inspected products can be the components used for production, semi-finished goods, or (most often) finished goods before shipment to a customer.

The ISO 2859 standard (derived from MIL-STD 105 E) defines an inspection as an “activity such as measuring, examining, testing, or gauging one or more characteristics of a product or service, and comparing the results with specified requirements to establish whether conformity is achieved for each characteristic”.