Stamped parts for the electrical industry are stamped insulation parts that safely separate current-carrying components in motors, transformers, switchgear and connectors. Typical ones are slot insulation, slot wedges, phase insulation, spacers and coverings from insulating materials such as Nomex, pressboard, PET film, mica or vulcanised fibre. The choice depends on thermal class, dielectric strength, tolerance and creepage resistance. GOBA has stamped these parts to drawing since 1959, from first sample to high-volume series.
Which insulation stampings the electrical industry needs
Every electrical machine with a winding needs insulation parts that hold the voltage between copper and lamination stack, between the phases and against the enclosure. The most common stamped parts:
- Slot insulation, insulating the lamination stack from the winding in the slot.
- Slot wedges, fixing the winding in the slot and closing it off at the top.
- Phase insulation, separating adjacent phases in the winding overhang.
- Spacers and distance pieces for defined clearances and creepage distances.
- Coverings and insulating washers at terminals, clamps and feedthroughs.
An example: in an electric motor the slot insulation is often stamped from an NMN laminate, a composite of Nomex, polyester film and Nomex. The part gets cuffs at the ends that overhang the lamination stack and extend the creepage paths. Whether these cuffs are folded or stamped in is decided by manufacturing together with you.
The quantities span a wide range. A prototype motor needs a few dozen slot liners, a pump series in white goods several hundred thousand a year. The same contour runs sometimes cut tool-free, sometimes from a full-cut tool. The geometry stays the same, the process follows the volume.
Typical materials
The material decides thermal class, dielectric strength and stamping behaviour. The insulating materials most often stamped in the electrical industry:
- Nomex, an aramid paper by DuPont of thermal class H up to 220 degrees, for slot and phase insulation in higher-loaded machines.
- Pressboard, a compressed cellulose board, economical for transformers and motors in the class A to E range, good in oil.
- PET films such as Mylar or Hostaphan, thin, tear-resistant and cheap, often laminated with nonwoven as DMD.
- Mica products for high voltages and temperatures, insensitive to partial discharges.
- Vulcanised fibre for mechanically loaded spacers and coverings with good strength.
For slot and layer insulation in motors, Nomex is the standard where thermal class counts. Where oil and price decide, GOBA reaches for pressboard. Which paper belongs in which motor is described in detail under insulation paper for electric motors.
Requirements for insulation stampings
A stamped part in the electrical industry must do more than fit. It carries an electrical and a thermal function. Design and purchasing set these characteristics together:
- Thermal class to IEC 60085, from A 105 degrees through F 155 degrees to H 180 degrees, matched to the winding temperature rise.
- Dielectric strength matched to operating and test voltage, with reserve for ageing.
- Contour tolerance, so the part seats reliably in the slot or winding overhang.
- Creepage and clearance distances that withstand contamination and moisture.
The thermal class is the first filter. A part made of PET film fails in a class H machine, no matter how cleanly it is stamped. That is why GOBA fixes the material by thermal class before geometry comes into play. Which class belongs to which material is shown in the overview of thermal classes of insulation.
In stamping itself the edge counts. A burr or a frayed cut edge shortens the creepage distance and becomes a weak point at the slot. GOBA keeps the cutting tools sharp and matches the cutting clearance to the material thickness, so the edge severs cleanly and the laminate does not delaminate. With thin films the press starts slower, otherwise the material tears at the hole.
Industries and applications
Stamped insulation parts sit in almost every electrical device with a winding. The application fields differ in voltage, temperature and environment:
- Electric motors from small drives to industrial motors, slot insulation and wedges.
- Transformers and reactors, layer and phase insulation, often in pressboard and oil.
- Switchgear and switching devices, coverings, barriers and spacers.
- E-mobility, traction motors and charging electronics with high thermal load.
- White goods, motors in washing machines, pumps and compressors in large quantities.
In electromobility especially the demands rise: higher voltages, tighter installation spaces, higher continuous temperatures. For these components GOBA produces insulation stampings from Nomex and mica in tight tolerances. In white goods, by contrast, the unit price counts. A washing-machine motor needs the same function but in millions of pieces, so GOBA stamps from a full-cut tool and delivers reproducibly, lot after lot.
From sample to series
GOBA accompanies an insulation stamping from the first drawing to running series. The flow:
- Send drawing or sample with material, thermal class, tolerances and quantity.
- GOBA checks material and process and prepares a technical quote.
- Produce first sample and check it in your machine, then written approval.
- Series start with documented first-article inspection and batch traceability.
For first samples GOBA cuts tool-free, and for the series a stamping tool is added at high volumes. The basics of these parts are under stamped parts. Whether your own tool pays off or awarding the work to GOBA is cheaper is settled by the comparison under Make or Buy for insulation parts.
GOBA as a partner
An insulation stamping stands or falls with the right material. Hit the thermal class cleanly, design the dielectric strength with reserve and tolerance only the function-critical dimensions tightly, and you get a part that lasts the life of the machine. GOBA has stamped slot insulation, wedges, phase insulation and coverings from Nomex, pressboard, PET, mica and vulcanised fibre since 1959, from first sample to high-volume series. Send your drawing to our stamping and forming, have insulation and molded parts produced, or discuss your drives with our team for electromobility and automotive. You will receive a technical quote, usually the same day.