Insulation parts

Slot Closures (Folded Slot Wedges)

Slot closures close the slots in rotor or stator after winding and are also called slot caps.

Class B, F, HBy the metre or to drawingChamfered one or both sides

In electric motor construction slot closures secure the winding in the slot: after winding they are pushed into the slot opening and hold the wires reliably in place. Slot closures are highly dimensionally stable, which makes them ideal as slot closures.

A wide range of geometries in terms of back width and leg length can be produced. For easier insertion into wound cores we make closures chamfered on one or both sides.

From samples to high-volume production, dimensions, lengths and quantities are free to choose.

By the metre or made to drawing

Standardised material by the metre is available in thermal classes B, F and H for cutting to length yourself. This is the economical solution for repair shops and for series with varying lengths.

To drawing we produce slot closures in special dimensions, geometries and tight tolerances. They are formed with our own tools and cut to length without damaging the profile. Clean cutting without profile damage is the quality difference you only notice during assembly: a crushed profile jams during insertion or sits loosely in the slot.

Manufacturing at Hauler & Hermann

We build our slot closure machines ourselves and run them with a control system developed in-house. The forming tools are made in our own tool shop, so new profiles and geometries are implemented within a few weeks. We process dimensionally stable sheet insulation and laminates of classes B to H, such as NPN laminate or Mylar polyester film. Production is certified to DIN EN ISO 9001 and DIN EN ISO 14001.

Selection criteria for purchasing and design

Four details define a slot closure: the slot opening geometry with back width and leg length, the required thermal class, the core length and whether a chamfer is needed for assembly. With a drawing or a sample part we quote at short notice, samples included on request. We also supply the matching slot liner for the same stator from a single source. Send us your enquiry via the contact form.

Product view

Isometric view, various shapes, variable lengths

Frequently asked questions

Is a slot closure the same as a slot wedge?

Not on our website. The slot closure, also called slot cap or folded slot wedge, is the folded part from flexible sheet insulation that closes the slot after winding. Rigid profiles from glass fibre laminate are on the slot wedges page.

Which thermal classes are available by the metre?

Standardised material for cutting to length yourself is available in thermal classes B, F and H. For other requirements we produce slot closures to drawing from the appropriate material.

Why are slot closures chamfered?

A chamfer on one or both sides makes it easier to push the closure into the wound core. Especially in automated assembly and with narrow slot openings, the chamfer prevents jamming.

Which geometries are possible?

Back width, leg length and overall length are free to choose. The profiles are formed with our own tools and cut to length without damaging the profile. Special geometries are implemented by our in-house tool shop within a few weeks.

Does Hauler & Hermann supply small quantities?

Yes. We supply everything from samples and small series to high-volume production. For repair shops and varying lengths, material by the metre is often the most economical choice.