MIL-STD-105E is an attribute sampling plan that contains tables and reference material to conduct inspection. ANSI / ASQ transferred it into Z1.4 which is still available today. ISO 2859 is the equivalent standard with minor difference. AQL is low as 0.01 percent but it cannot be used to inspect product with quality levels in the ppm range.
MIL-STD-105E Inspection Levels
Level I: for inspecting minor features of minor importance.
Level II: for inspecting features of major importance but the part failure does not cause a hazardous or an unsafe condition. Normal remote control product us using this inspection level.
Level III: for inspecting features that may cause critical defects that result in a hazardous or unsafe condition.
S-1: when act of inspection damages or destroys the inspection part. Use this inspection level only if the inspection costs are extremely severe to your company.
S-2: when act of inspection damages or destroys the inspection part. It uses for features of minor importance.
S-3: when act of inspection damages or destroys the inspection part. It uses for inspection of features with major importance.
S-4: when act of inspection damages or destroys the inspection part. It uses for inspecting features that could cause critical defects.
AQL Inspection table
Procedure in using AQL table
– Determine the lot size.
– Determine the inspection level.
– Check the table provides sample size and accept and reject criteria.
– Select the sample quantity from the lot for inspection.
– If less defects than the reject number you can accept the lot, or else reject the lot.
8D Report
8D report is widely used in electronic manufacturing industry as a standard procedure for resolve problems. Some factories use name of CAR (Corrective Action Report) with similar procedures.
8D report purpose is to identify, correct, and eliminate recurring problems. It establishes a permanent corrective action based on statistical analysis of the problem and on the origin of the problem by determining the root causes.
The 8 steps are:
D0: Preparation and Emergency Response Actions: Plan for solving the problem and determine the prerequisites. Provide emergency response actions.
D1: Form a Team: Form a team of people with product/process/technical knowledge. Teammates can provide new perspectives and different ideas for problem solving.
D2: Describe the Problem: Specify the problem by identifying in quantifiable terms the who, what, where, when, why, how, and how many (5W2H) for the problem.
D3: Develop Intermediate Containment Plan: Define and implement containment actions to isolate the problem from any customer or production line.
D4: Determine and Verify Root Causes and Escape Points: Identify all applicable causes that could explain why the problem has occurred. Also identify why the problem was not noticed at the time it occurred. All causes shall be verified or proved. One can use five whys or Ishikawa diagrams to map causes against the effect or problem identified.
D5: Verify Permanent Corrections for Problem: Using pre-production programs, quantitatively confirm that the selected correction will resolve the problem.
D6: Define and Implement Corrective Actions: Define and implement the best corrective actions and validate corrective actions with evidence of improvement.
D7: Prevent Recurrence of Problems: Modify the management systems, production arrangement, operation systems, practices, and procedures to prevent recurrence of same or similar problems.
D8: Congratulate to the Team: Recognize the collective efforts of the team.