QUALITY CONTROL
QUALITY CONTROL, TESTING AND INSPECTION
Highly sophisticated laboratory equipped with all modern instruments, machineries and trained manpower are always engaged with quality checking and process controlling activities. The pre-requisite for quality product is quality raw materials. For this reason we import finest quality of raw materials from abroad. Each and every raw material is constantly tested for physical, chemical, electrical and machanical properties in our laboratory before actual use in order to ensure best quality of the products. For Example the copper is tested for elongation, breaking load, resistance and chemical purity etc. While the other major raw material varnish is tested for solid contents, viscosity, specific gravity, flash point etc. Besides the vigilant supervsion of the production Engineers, the quality control team and the Chemist keep constant watch on the in-process materials to ensure ideal processing condition and quality.
CHARACTERISTICS
The Essential Characteristics of SEC Wires are:
- A. The insulation film is thin uniform and have superior electrical Properties.
- B. The insulation film have superior mechanical and heat resistance.
- C. Wires are soft, flexible and have smooth surface for efficient winding.
- D. Wires have stabilized properties for a long period.
- E. Wires are moderately priced.
SEC Wires featuring space-saving qualities are essential for miniaturization and sophistication of electronic equipment. Particularly demand is increasing for high quality SEC Wires having enough softness to be adoptable to high speed automatic winding machines used for making coils, which are capable of maintaining the above mentioned various properties even after severe winding process. To ensure that the manufactured Super Enameled Copper Wire conforms to the standard, sample from each production line is tested round the clock in our Laboratory. All the tests mentioned in the related BDS. are done to ensure that the product is strictly standard. Samples of wire from both the inner and outer end of each reel are subjected to different tests out of which the following are mentioned:
PHYSICAL TESTS
(Conductor diameter and overall diameter) Conductor diameter and overall diameter is checked with a precision instrument so that they conform to the values given in the table:
| SWG | DIAMETER OF CONDUCTOR | Area of conductor (Nom) (mm) | Copper Weight (bare) kg/km | Standard resistance of HDBC at 20° C (68°F) Ohm/Km | ||
|---|---|---|---|---|---|---|
| Nominal(mm) | Maximum (mm) | Minimum (mm) | ||||
| 1 | 7.620 | 7.648 | 7.590 | 45.600 | 405.400 | 0.387 |
| 2 | 7.012 | 7.028 | 6.970 | 38.600 | 343.200 | 0.458 |
| 3 | 6.403 | 6.428 | 6.370 | 32.180 | 286.100 | 0.549 |
| 4 | 5.893 | 5.918 | 5.860 | 27.270 | 242.400 | 0.649 |
| 5 | 5.386 | 5.408 | 5.349 | 22.770 | 202.400 | 0.777 |
| 6 | 4.880 | 4.908 | 4.849 | 18.680 | 166.060 | 0.948 |
| 7 | 4.472 | 4.498 | 4.439 | 15.700 | 139.530 | 1.129 |
| 8 | 4.065 | 4.088 | 4.029 | 12.970 | 115.320 | 1.366 |
| 9 | 3.660 | 3.688 | 3.629 | 10.510 | 93.430 | 1.686 |
| 10 | 3.252 | 3.278 | 3.219 | 8.302 | 73.790 | 2.136 |
| 11 | 2.946 | 2.974 | 2.915 | 6.816 | 60.560 | 2.601 |
| 12 | 2.642 | 2.668 | 2.616 | 5.481 | 48.720 | 3.238 |
| 13 | 2.337 | 2.360 | 2.314 | 4.289 | 38.130 | 4.137 |
| 14 | 2.032 | 2.052 | 2.012 | 3.243 | 28.830 | 5.471 |
| 15 | 1.829 | 1.847 | 1.811 | 2.627 | 23.350 | 6.756 |
| 16 | 1.626 | 1.641 | 1.610 | 2.075 | 18.430 | 8.552 |
| 17 | 1.422 | 1.438 | 1.407 | 1.589 | 14.130 | 11.180 |
| 18 | 1.219 | 1.232 | 1.207 | 1.163 | 10.380 | 15.210 |
| 19 | 1.016 | 1.026 | 1.006 | 0.811 | 7.207 | 21.910 |
| 20 | 0.914 | 0.924 | 0.904 | 0.657 | 5.838 | 27.040 |
| 21 | 0.812 | 0.820 | 0.805 | 0.519 | 4.613 | 34.220 |
| 22 | 0.711 | 0.718 | 0.704 | 0.397 | 3.532 | 44.700 |
| 23 | 0.610 | 0.615 | 0.605 | 0.292 | 2.595 | 60.850 |
| 24 | 0.558 | 0.563 | 0.554 | 0.245 | 2.181 | 72.420 |
| 25 | 0.508 | 0.513 | 0.503 | 0.202 | 1.797 | 87.630 |
| 26 | 0.457 | 0.462 | 0.452 | 0.164 | 1.460 | 108.200 |
| 27 | 0.416 | 0.421 | 0.412 | 0.136 | 1.212 | 130.400 |
| 28 | 0.375 | 0.378 | 0.372 | 0.111 | 0.987 | 160.100 |
| 29 | 0.345 | 0.348 | 0.342 | 0.093 | 0.833 | 189.500 |
| 30 | 0.315 | 0.318 | 0.312 | 0.079 | 0.703 | 227.900 |
| 31 | 0.294 | 0.297 | 0.291 | 0.068 | 0.606 | 260.400 |
| 32 | 0.274 | 0.277 | 0.271 | 0.059 | 0.525 | 300.600 |
| 33 | 0.254 | 0.257 | 0.251 | 0.051 | 0.451 | 350.600 |
| 34 | 0.233 | 0.236 | 0.230 | 0.043 | 0.381 | 414.300 |
| 35 | 0.213 | 0.216 | 0.210 | 0.036 | 0.317 | 484.161 |
| 36 | 0.193 | 0.195 | 0.190 | 0.029 | 0.260 | 589.631 |
| 37 | 0.173 | 0.175 | 0.170 | 0.023 | 0.209 | 735.530 |
| 38 | 0.152 | 0.155 | 0.150 | 0.018 | 0.161 | 950.960 |
| 39 | 0.132 | 0.135 | 0.129 | 0.012 | 0.122 | 1261.220 |
| 40 | 0.122 | 0.125 | 0.119 | 0.010 | 0.104 | 1476.110 |
| 41 | 0.112 | 0.115 | 0.110 | 0.009 | 0.088 | 1752.130 |
| 42 | 0.102 | 0.104 | 0.099 | 0.008 | 0.073 | 2112.860 |
| 43 | 0.091 | 0.094 | 0.088 | 0.007 | 0.058 | 2652.460 |
| 44 | 0.081 | 0.084 | 0.079 | 0.005 | 0.046 | 3347.770 |
| 45 | 0.071 | 0.074 | 0.068 | 0.004 | 0.035 | 4364.810 |
| 46 | 0.061 | 0.063 | 0.059 | 0.003 | 0.026 | 5904.450 |
Resistance of the Enamel Cover to Abrasion
This test is applicable to wires of diameter 0.230mm (bare) and larger. The test is performed in an automatic Abrasion testing apparatus by repeatedly scrapping the surface of the enameled wire with the side of a loaded needle. 0.4 mm dia, steel sewing needle which is held at right angle to the wire. The apparatus is equipped with an electrical circuit so arranged that a voltage of 12 volt d.c. is applied between the needle and the conductor and that when the needle wears the enamel an electrical contact is made between the needle and the conductor. The motion stops as soon as a current of approximately 5 mA passes. Three such tests are performed on a sample at longitudinal distance of 25mm and angular distance of 120° each time. While for BDS requirement, this average number of scrapping for Three tests should not be less than 30 and no individual value should be less than 15, the corresponding minimum values for our wires are usually 45 above and 30 above respectively.
Flexibility and adherence to enamel
Our enameled wires meet the requirements of (i), (ii) or (iii) below according to the size.
- (i) Wires of diameter less than 0.250mm (bare): A specimen of the enameled wire 25cm long between grips is steadily stretched to 31cm at the rate of 30 cm/min (or to the breaking point of the wire, should this occur first). The specimen is then wound for contiguous turns on a polished metal mandrel having a diameter three times bigger than that of the bare wire. The covering shows no crack.
- (ii) Wires of diameter 0.250mm to 2.00mm (bare) inclusive: A specimen of the enameled wires is wound for ten contiguous turn round itself. The covering shows no crack.
- (iii) Wires of diameter greater than 2.00mm (bare): A specimen of the enameled wire is wound for ten contiguous turns round a polished metal mandrel having a diameter three times the diameter of the bare wire. The covering shows no crack. All the above samples are checked for cracks under a Microscope.
Heat Shock
(A) For SECW based on Polyvinyl acetal varnish: A sample of the enameled wire prepared as described in clause 3.3 (i), (ii) or (iii) according to the size of the wire, is placed in an oven operating at 155°C to 160°C for 30 minutes. The covering shows no crack. (B) For SECW based on polyester Varnish: The wires shall meet the requirements of (i) or (ii) below according to size:
- (i) Wires of diameter 0.914 mm (bare) and less : A specimen of the enameled wire wound for ten contiguous turns round a polished metal mandrel having a diameter four times the diameter of the bare wire is heated in an air oven at 200°C to 205°C for 30 minutes. The sample is allowed to cool to room temperature. The covering shows no crack.
- (ii) Wires of diameter greater than 0.914 mm (bare): A specimen of the enameled wire wound for ten contiguous turns round a polished metal mandrel having a diameter six times the diameter of the bare wire is heated in an air oven at 200°C to 205°C for 30 minutes. The sample is allowed to cool to room temperature. The covering shows no crack.
Heat ageing
(A) For SECW based on polyester Varnish: A specimen of the enameled wire unstretched and unbent is heated for 120 hours in an oven in free air at a temperature of 180 ± 2°C. The specimen is then allowed to cool to room temperature and wound for ten contiguous turns on a polished metal mandrel having a diameter three times the diameter of the bare wire. The covering shows no crack.
(B) For SECW based on Polyvinyl Acetal Varnish: A specimen of the enameled wire unstretched and unbent is heated in an oven in free air at 130±2°C. The period of heating shall be 96 hours. The specimen is then allowed to cool to room temperature and tested as below according to size.
- (i) Wire of diameter 0.900mm (bare) and less : The aged specimen is wound for ten contiguous turns on a polished metal mandrel having a diameter three times that of bare wire. The covering shows no crack.
- (ii) Wires of diameter greater than 0.900mm (bare): The aged sample is wound for ten contiguous turns on a polished metal mandrel having a diameter four times the diameter of the bare wire. The covering shows no crack.