What Are the Differences Between Quality Walls, Quality Gates, and Containment Gates?
In manufacturing there are many “protect the customer” methods implemented by and/or forced upon suppliers while they work to improve product and process quality.
A Quality Wall is generally a communication center for organizations that generate quality alerts from customer complaints. Upon receipt of a complaint; a description of the defect with a picture or graphic is posted on the quality wall. There is generally a morning meeting of 10 – 15 minutes where the quality manager and production management reviews the quality alerts with the operators for awareness. When the defect is not repeated for a period of time the quality alert is removed or crossed out and the latest quality alerts are emphasized in the morning meeting.
Quality Gates are generally put in place to check parts and flag defects with some post it marking/arrow etc. and these defects are recorded and reported to Quality Management. The defective parts flow to a repair area where they are repaired and shipped. The quality records are used for reporting First Time Quality and defect data.
Containment gates are in place to force “build in station”. These gates are generally owned by manufacturing. When a defect is found, the part is returned to the operator workstation and repaired by the production operator. The operator is made aware of the issue and often is still running the same part allowing for an established breakpoint and for all product to be repaired in a timely manner.
This methodology allows for immediate corrective action and stops the flow of defects. An Andon System is generally used for containment gates to alert production supervision to a stoppage of process. A team leader/and or supervisor responds to assist in solving the issue and beginning the problem solving activities. Once defects are no longer being found at the containment gate – it is removed and the quality system is updated to reflect any error proofing etc. that was developed during the containment period.
Quality walls are useful for communication and bringing attention to issues when there is a customer complaint. They are useful for team meetings and often important metrics are reviewed during sessions at the quality wall. They are intended to be permanent and become of the Quality System.
Quality gates are useful for inspection of parts and flagging defects that are then sent to repair. The data collected is used to calculate first time quality and ensures parts are repaired before shipping. Defects generally flow to the repair area and improvement trends can be tracked through quality gate data. These stations are generally owned by the quality department and once in place become part of the quality system.
Containment gates are put in place to enforce “build in station”. Because defective parts are routed back to the workstation, the operator is aware of the issues and the flow of defects is stopped. Once engineering/production has the proper fixes in place, quality verifies the prescribed exit criterion has been met and containment is stopped. Usually an andon system will be left in place at the workstation and whenever there is a problem the operator will activate the and-on and get team leader/supervisor help and resume production.
If in-house containment is not effective to protect the customer, the next step (short of actually solving the problems) is to put the supplier on controlled shipping. This is when the parts to be contained are shipped to a third party inspection facility; inspected, and shipped to the customer. This step is usually a last resort prior to re-sourcing the product.
-Ed Baccus, Managing Principal