In a former position, we had a machine for trimming leads. It had a horizontal blade, high speed saw. We had to use it on one type board for a customer that wanted very short lead protrusion.(RF stuff) The blade had to be very sharp. Setup errors could easily destroy a board. Bow and Twist issues could easily destroy a board. Our system was manual, X and Y plane. Move too fast or too slow and you got flags, and metal chips. The vacuum (ESD?!) could not clean up every thing. So, the station quickly became a mess of little tiny metal pieces. It was a nightmare to control the process. DON'T GO THERE IF YOU DON'T HAVE TO. Do not even think of it if you have a no-clean process. > -----Original Message----- > From: TechNet [mailto:[log in to unmask]]On Behalf Of Stephen R. Gregory > Sent: Tuesday, December 18, 2001 12:12 AM > To: [log in to unmask] > Subject: [TN] Mass lead trimming systems... > > > Hi All! > > The subject has come up here about mass lead trimming systems. > From what I've > learned, they have their place. But in our situation, I have the > opinion that > they aren't warranted here. We do a lot of class-3 electronics, > have hardware > (screws and whatnot from connectors) that hang below the lead length > requirements. > > Many of the requirements on the asssembly drawings of products we build, > still call out MIL standards, even though they are obsolete, we are still > obligated to build to these standards...those that build product > according to > these standards, and have tried to deviate, or change, from what is > documented on these standards know what a task that is...it isn't going to > change. > > So, in my opinion, mass lead trimming systems have no place here. > There are > too many things that call out extra work that will need to be > done because of > these systems. > > The J-STD's call out that if lead trimming is performed after wave solder, > then the joints should be either re-reflowed, or inspected under 10X to > ensure that there has been no fractures... > > I've also heard that these systems need METICULOUS maintenance. If they > aren't maintained perfectly, they will cause major problems. > > Just want to hear from any of you that have direct experience with these > systems.. > > My position is that you either prep PTH components so that lead length > requirements are met after soldering, and/or you make the adjustments that > are available on your auto-insertion machines so that you meet lead length > requirements...if you have to trim after wave solder, then either > you haven't > specified the proper component prep, or you need to adjust the > cut and clinch > on your auto-insertion equipment...I come the school that you can > do things > before wave solder that keeps lead length requirements within > specifications, > and not require mass lead trimming afterwards. > > So with that being said, what opinions are out there about mass > lead trimming > systems? > > As always, all ya'll are the best... > > -Steve Gregory- > > ------------------------------------------------------------------ > --------------- > 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 ---------------------------------------------------------------------------------