Manufacturing process of plastic commutator

Update:15 Nov 2021

In the geared motor, the plastic commutator generally has the following main manufacturing processes (take the mica plastic compression commutator as an example): Commutator piece and mica piece manufacture, commutator piece assembly manufacture, plastic die-casting and post-casting Heat treatment a car shape. Milling mica tank, dipping insulating paint, milling wire slot, hanging tin, and quality inspection.
1. Commutator blades and commutator blade copper bars mainly require high electrical conductivity, sufficient mechanical strength and hardness, wear resistance, easy processing, and low price. Among them, the electrolytic copper (red copper) TPT cold-drawn trapezoidal copper bar is commonly used. For heat-resistant and high-speed motors, cadmium copper, zirconium copper, and chromium copper with good wear resistance, high mechanical strength, and arc resistance are used. Micro DC motors can also be partially gold-plated with silver nickel copper and red copper plates. Trapezoidal copper bars are processed by the raw material factory, and there are special standards for trapezoidal copper bars for motors. It specifies the tolerance range of the cross-sectional dimensions of cold-drawn copper bars, usually with limit sample inspections. The connection between the commutator segment and the winding outlet head is often linear connection, riser connection, wire hook connection, etc. In small motors, when the commutator is small in size and a riser piece is required, the riser piece and the commutator piece are used to form an integrated structure. The main processing methods of commutator blanks are punching, milling or extrusion processing. Generally, commutator segments with a thickness of less than 7 mm are punched with a special die, and the commutator segment surface together with dovetail grooves, risers, etc. Blanking and forming, high efficiency, easy to guarantee the quality dream, and convenient for the recycling of copper scraps. After punching, the burrs are removed from the copper sheet, and it can be transferred to the next process after cleaning.

2. The mica insulating sheet is a plastic commutator insulated with mica sheet, and its mica insulating sheet is mostly cut and punched out of artificial mica board. The artificial mica board is made by sticking small Yaoran mica flakes and mica powder together with an adhesive. Artificial mica board is divided into muscovite board, phlogopite board and epoxy commutator powder mica board. The latter two are commonly used in small commutators. The grades are: shellac commutator phlogopite board, epoxy commutator powder mica board. The large mica board is cut into strips with a shearing machine, and then a mica sheet with dovetail grooves is punched out with a forming and punching die on the punching machine. The dimensions in all directions should be about 1 mm larger than the commutator to reduce the short circuit between the plates after plastic compression.

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