Hi, For historic interest.
Way back in the early 1970's I was employed by a company that made thermocouples. The smallest was 0.5mm diameter and was sheathed in stainless steel. The actual thermocouple wires were insulated from the sheath and themselves by magnesium oxide. We also designed, built and operated a capacitor discharge welder (CDW) to make the thermocouples. We would start with the raw cable on a reel and cut to length. We would then (using a microscope to view what we were doing) clean the area around the thermocouple wires, removing the MgO to expose sufficient to weld and the wires pushed together. The other end of the thermocouple wires were connected to the return of the CDW and then the capacitors were charged to the "correct" value. The welding torch was aligned with the thermocouple wires and argon gas was started to form an inert shield around the weld area. The discharge was executed and the weld inspected for quality and to make sure that the weld is inside the sheath. The final stage was to back-fill the sheath with MgO and fit a stainless steel cap over the (now insulated) thermocouple junction. The CDW was used to weld the cap in place. The cold end was terminated with flexible "tails" and encapsulated in a water-tight seal. These were used in nuclear power stations. The surprising thing to me was how little your hands would shake when working under the microscope ! The name of the company was BICC Pyrotenax. Regards Tim ************************ Tim Haynes A1N21 Electromagnetic Engineering Specialist SELEX Sensors and Airborne Systems 300 Capability Green Luton LU1 3PG ( Tel : +44 (0)1582 886239 7 Fax : +44 (0)1582 795863 ) Mob : +44 (0)7703 559 310 * E-mail : [email protected] P Please consider the environment before printing this email. There are 10 types of people in the world-those who understand binary and those who don't. J. Paxman From: [email protected] [mailto:[email protected]] On Behalf Of Nick Williams Sent: Monday, July 21, 2008 8:47 PM To: Bolintineanu, Constantin Cc: [email protected] Subject: Re: THERMOCOUPLE WELDER *** WARNING *** This mail has originated outside your organization, either from an external partner or the Global Internet. Keep this in mind if you answer this message. It never occurred to me that someone might make a special gadget for this job - I just use our workshop oxy-acetylene torch! Nick. At 15:04 -0400 18/7/08, Bolintineanu, Constantin wrote: >Dear Colleagues, > >I would like to kindly ask you in regard to the THERMOCOUPLES WELDERS >that you are using. >Information regarding the suppliers, and best performances and >reliability, with not to many headaches are very much appreciated. I >must admit that what we found is not an approved type... >I would prefer to understand which is the best solution without using >too many consumables. > >Please accept in advance my many thanks for your replies. > >Respectfully yours, >Constantin > >Constantin Bolintineanu P.Eng. >TYCO SAFETY PRODUCTS CANADA >3301 LANGSTAFF Road, L4K 4L2 >CONCORD, ONTARIO, CANADA >e-mail: [email protected] >Tel: 905 760 3000 ext 2568 >Fax: 905 760 3020 > - This message is from the IEEE Product Safety Engineering Society emc-pstc discussion list. Website: http://www.ieee-pses.org/ To post a message to the list, send your e-mail to [email protected] Instructions: http://listserv.ieee.org/request/user-guide.html List rules: http://www.ieee-pses.org/listrules.html For help, send mail to the list administrators: Scott Douglas [email protected] Mike Cantwell [email protected] For policy questions, send mail to: Jim Bacher: [email protected] David Heald: [email protected] All emc-pstc postings are archived and searchable on the web at: http://www.ieeecommunities.org/emc-pstc SELEX Sensors and Airborne Systems Limited Registered Office: Sigma House, Christopher Martin Road, Basildon, Essex SS14 3EL A company registered in England & Wales. Company no. 02426132 ******************************************************************** This email and any attachments are confidential to the intended recipient and may also be privileged. If you are not the intended recipient please delete it from your system and notify the sender. You should not copy it or use it for any purpose nor disclose or distribute its contents to any other person. ******************************************************************** - This message is from the IEEE Product Safety Engineering Society emc-pstc discussion list. Website: http://www.ieee-pses.org/ To post a message to the list, send your e-mail to [email protected] Instructions: http://listserv.ieee.org/request/user-guide.html List rules: http://www.ieee-pses.org/listrules.html For help, send mail to the list administrators: Scott Douglas [email protected] Mike Cantwell [email protected] For policy questions, send mail to: Jim Bacher: [email protected] David Heald: [email protected] All emc-pstc postings are archived and searchable on the web at: http://www.ieeecommunities.org/emc-pstc
