Olivia, Kathy, et al., what kinds of defects is inspection missing, and what fraction of defects is it catching? The inspector missed something - so what else is new? As we all know, visual inspection is typically said to be 85% effective. The few times (no more than 4) that I have been able to check inspection effectiveness against true process performance, I have calculated confidence intervals that included the 85% number. My view is that inspection can serve as a pretty good safety net, to catch a problem of, say, a polarized capacitor installed backwards on each of 20 board, but in finding needle-in-the-haystack problems its capabilities are limited. As the frequency of the occurence of defects decreases, the probability of detection of any individual defect decreases, as one might expect and which research result was reported by Malcolm Gladwell in the New Yorker a few weeks back. (That's why paying airport inspectors more won't make planes safer.) Also, I tell people our inspection instructions do not provide for any "overlap". The statement that "three inspectors missed it" is not true - one inspector has the job of looking for, say, surface mount solder nonconformances and no other inspector will even try. Two people have a chance to make a mistake - the person who installs the part and one inspector. Lou Hart -----Original Message----- From: Olivia Mc Dermott [SMTP:[log in to unmask]] Sent: Thursday, January 03, 2002 10:01 AM To: [log in to unmask] Subject: Re: [TN] Final Audit/Inspection We do have inspection points throughout the process. The problem is they are also missing defects and letting them through to final inspection.I wondered if there is a direct instruction on inspecting. 1. you do this 2. you do this. >From: Kathy Kuhlow <[log in to unmask]> >Reply-To: "TechNet E-Mail Forum." <[log in to unmask]> >To: [log in to unmask] >Subject: Re: [TN] Final Audit/Inspection >Date: Thu, 3 Jan 2002 08:49:32 -0600 > >I would first start with some in-process sampling so you can pinpoint what >types of defects the process is currently producing. Do you see more >missing components from surface mount or do you have a problem withe solder >shorts on the solder side because of wave issues or snapping problems. >All to many organizations use a final inspection as a safety net. In my >dream world I would have no one doing final inspection but bring it back to >the process and do the inspection at the process through auditing by both >production and quality personnel so immediate feedback can be accomplished. > Otherwise you get data that is out of date and you can't really take >effective corrective actions, especially if your world is as a CM or small >run lots. > >If you must do a final inspection then we typically start with a complete >part verification (value, polarity, AVL check) than solder (quality, >quantity, lead placement) and finally any specific customer >instructions(labeling, rev add, etc). > >Kathy ><< TEXT.htm >> _________________________________________________________________ Send and receive Hotmail on your mobile device: http://mobile.msn.com ------------------------------------------------------------------------ --------- Technet Mail List provided as a free service by IPC using LISTSERV 1.8d To unsubscribe, send a message to [log in to unmask] with following text in the BODY (NOT the subject field): SIGNOFF Technet To temporarily halt delivery of Technet send the following message: SET Technet NOMAIL Search previous postings at: www.ipc.org > On-Line Resources & Databases > E-mail Archives Please visit IPC web site (http://www.ipc.org/html/forum.htm) for additional information, or contact Keach Sasamori at [log in to unmask] or 847-509-9700 ext.5315 ------------------------------------------------------------------------ --------- --------------------------------------------------------------------------------- Technet Mail List provided as a free service by IPC using LISTSERV 1.8d To unsubscribe, send a message to [log in to unmask] with following text in the BODY (NOT the subject field): SIGNOFF Technet To temporarily halt delivery of Technet send the following message: SET Technet NOMAIL Search previous postings at: www.ipc.org > On-Line Resources & Databases > E-mail Archives Please visit IPC web site (http://www.ipc.org/html/forum.htm) for additional information, or contact Keach Sasamori at [log in to unmask] or 847-509-9700 ext.5315 ---------------------------------------------------------------------------------