Heating in these electric heating bags occurs when current flows through a conductive liquid, which is used as part of the heating mechanism. However, if this charged liquid escapes through the vent hole, it can lead to serious safety risks such as electric shocks or burns. In our testing of 20 sample groups, 17 failed both the electrical strength and leakage current tests due to improper venting. This failure was primarily caused by the electrode being exposed to the conductive liquid, leading to an input power issue. As temperature fluctuates, the resistance of the liquid changes, causing significant variations in input power. Some products even showed input power values two to three times higher than their rated power.
To cut costs, some manufacturers only include a thermostat in series within the design, using it both for temperature control and protection. However, during abnormal testing, the thermostat may short-circuit, causing the device to remain in a charging state. This leads to overheating, swelling, and potentially bursting, with high-temperature liquid splashing out. For "electric wire type" heating bags, the main issues are unrelated to structural design. Instead, they fail due to material-related problems—specifically, 13.1% of the "electrode type" samples failed because the materials didn't meet heat resistance or flame resistance standards.
The root cause is often poor material selection. The power supply terminals or appliance sockets failed the ball pressure test at 125°C and the glow wire test at 750°C, indicating that insulating materials were not suitable for high temperatures. There's a risk of deformation or burning under stress. Additionally, two other failures were due to the power cord diameter being too small (less than 0.75mm²) for appliances rated at 3A or higher, increasing the risk of fire from overheated cords.
Signage and labeling also posed issues. About 9.5% of the samples had incomplete information on the label, while 31.8% had more severe issues. According to IEC 60335-1:2001+A:2004, all devices must clearly show the rated voltage, power supply symbol, input power, manufacturer details, model, and class II marking. Out of the 20 groups tested, 8 of the "electrode type" and 7 of the "electric wire type" failed to meet these requirements.
Most of these issues stem from a lack of understanding of the standards by manufacturers. For example, 16.7% of the "electrode type" samples failed due to structural flaws, while 22.7% of the "electric wire type" samples failed due to incorrect power ratings. Some manufacturers altered the indicated power to match customer demands, but the actual measured power exceeded the allowed tolerance, leading to non-compliance.
From our analysis, we found that the unqualified items fall into three main categories: structural issues, material defects, and signage or power labeling problems. In the 20 groups tested, the "electrode type" had 84 total defects, while the "electric wire type" had 22. This clearly shows that the "electric wire type" has a much higher qualification rate. However, both types have their own challenges—structural issues for the "electrode type" and material selection for the "electric wire type." With targeted improvements, these issues can be resolved effectively.
Link Pin
Link
Pin is a device used for fastening/connecting objects or material together, mostly the Link
Pin which QFAP supplied are applied in diggers, excavators, trucks, or
railway equipments.
Most of our customers were from North America,
Europe and Chinese domestic market.
Annual Production Capability: 200,000pcs
Materials: carbon steel, stainless steel, alloys
steel, steel tube, etc.
Surface treatment:
painting, zinc plating, blackening, passivation, nickel plating, oiled, etc.
Heat treatment:
according to customer`s requirement.
QFAP have specialized in
producing high precision Agriculture Parts more than 10years, Because of the
long term cooperation, we could supply our customers not only the products but
also our recommendation on the designs to saving costs.
Link Pin,Linking Pin Model,Link Pin Kit,Link Pin Code
SHAOXING QIFENG AUTO PARTS CO., LTD. , https://www.sxqfap.com
