1. Loose or cracked contacts
Contacts are the electrical contact parts that complete the switching load of the relay. Some products' contacts are assembled by riveting and pressing. The main defects are loose contacts, cracked contacts, or excessive deviation in size and position. This will affect the contact reliability of the relay. The occurrence of loose contacts is caused by unreasonable dimensions of the matching parts between the spring and the contact, or improper adjustment of the riveting pressure by the operator. Contact cracking is caused by excessive material hardness or excessive pressure. The three-phase clamp phase volt-ampere meter can directly display the vector diagram, especially suitable for power supply and consumption units to check the wiring status of the electricity metering system and relay protection system. For contacts of different materials, different material processes are adopted. Some contact materials with higher hardness should be annealed before contact manufacturing, riveting, or spot welding. Contact manufacturing should be careful because there are tolerances in materials, so the cutting length should be determined after trial. Contact manufacturing should not have burrs, scratches, or incompleteness. Contact riveting deviation is caused by the operator not aligning the mold correctly or the upper and lower molds being misaligned. Contact damage and contamination are caused by not cleaning the oil and iron filings on the mold. No matter what kind of defect, it will affect the working reliability of the relay. Therefore, during the contact manufacturing, riveting, or welding process, it is necessary to comply with the self-inspection regulations of first-piece inspection, middle sampling, and final inspection to improve assembly quality.
2. Unstable relay parameters
Many parts of electromagnetic relays are assembled by riveting. The main problem is loose riveting or poor bonding strength. This defect will cause unstable relay parameters, large parameter changes under high and low temperatures, and poor resistance to mechanical vibration and impact. The main reasons for this defect are oversized or undersized riveted parts, improper placement of parts, unqualified tooling and molds, or incorrect installation. Therefore, before riveting and welding, it is necessary to carefully check whether the tooling, molds, and riveted parts meet the requirements.
3. Deformation of electromagnetic system riveted parts
After riveting, parts may bend, twist, or be upset, causing difficulties in assembly or adjustment in the next process, and may even lead to scrapping. The main reasons for this defect are parts being too long or too short, uneven force during riveting, mold assembly deviation or design dimension errors, and improper placement of parts. During riveting, operators should first check whether the dimensions, appearance, and molds of the parts are correct. If the mold is not installed in place, it will affect the assembly quality of the electromagnetic system or cause core deformation and upsetting.
4. Damage to glass insulators
Glass insulators are made by sintering metal pins and glass. During inspection, assembly, adjustment, transportation, and cleaning, it is easy to cause bending of pins, chipping or cracking of glass insulators, resulting in air leakage and reduced insulation and voltage resistance performance. Pin rotation can also cause displacement of contact springs, affecting reliable on-off of the product. This requires assembly operators to handle parts gently throughout the relay production process, arrange parts neatly in transfer boxes, and not allow pulling or twisting of lead pins during assembly or adjustment.
5. Coil faults
There are many types of coils used in relays, some with outer wrapping and some without. Coils should be placed separately in special containers. If they collide and intertwine, separating them may cause wire breakage. During the riveting of the electromagnetic system, the pressure of the hand press and press machine should be adjusted appropriately. Excessive pressure will cause coil wire breakage, coil frame cracking, deformation, or winding breakdown. Insufficient pressure will cause loose winding and increased magnetic loss. Multi-winding coils generally use different colored leads as the head. During welding, attention should be paid to distinguish them, otherwise the coil may be welded incorrectly. For coils with start and end requirements, the start and end are usually marked. During assembly and welding, attention should be paid, otherwise the relay polarity will be reversed.
