US Navy Preference for Dreisilker Repair Process for over 20 Years (News)

In the editions of the NAVSEA S6260-BJ-GTP-010 "Electrical Machinery Repair, Electric Motor Repair, Shop Procedures Manual" starting in the 1980s (this is the Navy Rewind bible), the Dreisilker method (by name) is outlined.

As noted by the Navy rewind manual (Section 8-14): “Oven Burnout Procedure: The simplest, but most time consuming, method of preparing a failed winding for removal from a stator is a pre-heated, temperature-controlled burnout oven that has a forced exhaust system [to atmosphere – see the EPA article] until all the insulating materials have turned to ash and the windings can be removed. This will take at least 12 hours. The oven temperature during burnout should not exceed 700F (600F for T-frame and aluminum stators), measured by thermocouple on stator iron. After removing the stator from the oven, allow it to stand and cool to room temperature.”

The motor is not allowed to be rapidly cooled to reduce the amount of core warping and only one stator in the oven at a time. Both of these requirements are ignored by virtually all motor repair facilities. Normally, motors are stacked in an oven, thermocouples unused, and, in many cases, temperature suppression systems turned off to speed the process.

As noted, following discussion of the burnout process:

8-17: "Warming and pulling is the preferred method for stripping the stator. This method is to be used on motors with sealed insulation systems and can also be used with aluminum frame motors. This method uses lower temperatures, so it does not damage the laminations."

This is the Dreisilker/Thumm method of coil removal.

Dreisilker is mentioned twice more in the repair winding removal process: Section 8-18 – “Suitable end turn cutoff devices are manufactured by Lancer of Wisconsin and Dreisilker Electric Motors, Inc. of Glen Ellyn, Illinois;” and, Section 8-20 – “Commercial devices suitable for the operation are made by S and W Enterprises of Savannah, Georgia, and Dreisilker Electric Motors of Glen Ellyn, Illinois.”

The process is outlined as not damaging the condition of electric motors versus the burnoff oven. A copy of this section is available (public information) by contacting the MotorDoc.