Incoming Inspection Items for Thermal Fuses
1. Visual Inspection
1. Printing: Model number, batch code and manufacturer logo are clearly and completely printed without missing, blurring or fading.
2. Body: No cracks, deformation, damage or scorch marks on the housing; no glue overflow, seal cracks or material leakage at the sealing part.
3. Leads: No oxidation and blackening, insulation damage, wire breakage, severe bending or exposed copper wires.
2. Dimension Measurement
Measure overall length, housing length/width/thickness, lead wire diameter, exposed lead length, terminal bending size and lead spacing against drawings; all dimensions shall be within tolerance.
3. Electrical Performance Test
1. Room-temperature resistance: Measure resistance between two leads with a multimeter; the reading shall meet specification tolerance, and distinguish high-resistance and low-resistance types.
2. Continuity: No open circuit or internal short circuit at ambient temperature.
3. Withstand voltage test: Apply standard high voltage between leads; no breakdown, creepage or flashover occurs.
4. Key Thermal Performance Test (Critical Control Item)
1. Trip temperature
Heat up evenly with a constant-temperature oil bath or oven, record the cut-off temperature which must fall within the specified range. The fuse will form a permanent open circuit after tripping and cannot recover conductivity.
2. Non-operating
1. Visual Inspection
1. Printing: Model number, batch code and manufacturer logo are clearly and completely printed without missing, blurring or fading.
2. Body: No cracks, deformation, damage or scorch marks on the housing; no glue overflow, seal cracks or material leakage at the sealing part.
3. Leads: No oxidation and blackening, insulation damage, wire breakage, severe bending or exposed copper wires.
2. Dimension Measurement
Measure overall length, housing length/width/thickness, lead wire diameter, exposed lead length, terminal bending size and lead spacing against drawings; all dimensions shall be within tolerance.
3. Electrical Performance Test
1. Room-temperature resistance: Measure resistance between two leads with a multimeter; the reading shall meet specification tolerance, and distinguish high-resistance and low-resistance types.
2. Continuity: No open circuit or internal short circuit at ambient temperature.
3. Withstand voltage test: Apply standard high voltage between leads; no breakdown, creepage or flashover occurs.
4. Key Thermal Performance Test (Critical Control Item)
1. Trip temperature
Heat up evenly with a constant-temperature oil bath or oven, record the cut-off temperature which must fall within the specified range. The fuse will form a permanent open circuit after tripping and cannot recover conductivity.
2. Non-operating
