Commutator Mica Board
The P9 Epoxy Commutator Mica Board is a rigid, high-performance insulating material for DC motors, offering uniform thickness and effective insulation at 130°C.
1. Product Introduction
The P9 Epoxy Commutator Mica Board is a rigid, board-shaped insulating material made from epoxy resin adhesive bonded mica paper, which is baked and pressed.
This product features uniform thickness and high electrical performance, making it suitable for insulating commutator copper segments in DC motors operating at a working temperature of 130°C.
2. Technical Parameters
- Dimensions
(1) Area should be no less than 250×500 square millimeters. An area of no less than 250×300 square millimeters is allowed for up to 5% of the total weight. For areas smaller than the specified size (which may include large mica boards with obvious markings for voltage breakdown points), shipment will be based on an agreement between the supplier and the buyer.
(2) Thickness and tolerance are as shown in the table below.
| Nominal Thickness | Tolerance | |
| Average Value | Individual Value | |
| 0.4-0.15 mm (in steps of 0.05 mm) | ±0.03mm | ±0.06mm |
2. Appearance: The commutator mica board should have neat edges, with no pinholes, surface bubbles, foreign impurities, or delamination at the edges and corners.
3. Composition Content: See the table below.
| Mica | Adhesive | Volatile Matter |
| Not Less Than 90% | Not Less Than 10% | Not Less Than 1.0% |
4. Shrinkage Rate: See the table below
| Nominal Thickness (mm) | Under a pressure of 600 kg/cm² and a temperature of 20±5°C (not exceeding) | Under a pressure of 600 kg/cm² and a temperature of 160±5°C (not exceeding) |
| Not Less Than 90 | 9% | 2.5% |
5. Smoothness: The commutator mica board, tested under a pressure of 600 kg/cm² and a temperature of 160±5°C, should show no adhesive dripping or mica sliding at the edges.
6. Breakdown Strength: The breakdown strength under normal conditions should be no less than 20 kV/mm. The individual values of breakdown strength should be no less than 75% of the standard value.
7. Voltage Withstand: The commutator mica board should withstand a voltage calculated at 9 kV/mm without breakdown.
8. Delamination Rate: See the table below. (No specification required for mica boards with a thickness of 1.0 mm or more.)
| Standard Thickness Range and Sample Area (mm) | Delamination Rate |
| 0.4-0.65 20 × 20 |
Not Exceeding 5% |
| 0.7-1.0 20 × 40 |
Not Exceeding 10% |
