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- 日期: 2022-08-04
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The main reasons for shortening the life of polyester ironing feltThe ironing felt is the most vulnerable link in the whole laundry room equipment. When the ironing machine is not running normally during the washing process, the ironing felt will be damaged first, and the lifespan will be shortened eventually.
The main reasons for shortening the life of the ironing felt are as follows:
1-Mechanical reason: abnormal friction
2- Chemical reason: hydrolysis/chemical hydrolysis/pyrolysis
1. Mechanical reasons
Symptoms: The felt is transversely broken or thinned so that there are fewer and fewer fibers on the grooved bed.
1) Improper coordination of ironing rollers, grooved beds and other components will result in excessive tension on the ironing felt and eventually damage.
2) The temperature of the boiler is not enough, so that the bad bed presses the ironing felt until it breaks or causes a spring to penetrate the double ironing felt.
3) After several hours of operation after installing the new ironing felt, the excess ironing felt beyond the boundary of the second circle should be cut off, otherwise it will cause wet marks on the linen and extra pulling on the ironing felt.
4) Insufficient lubrication and inferior wax lead to additional tearing of the hot felt.
5) The steam valve must work normally, otherwise a low temperature area will be generated in the grooved bed due to shrinkage. This will accelerate the destruction of the ironing felt and also affect the ironing quality.
6) When installing a new ironing felt, be sure to fix the screws and washers on both sides to the two ends of the ironing roller and sew on the roller surface with a thin steel wire every 30 centimeters, so as to avoid the deformation caused by a section falling off. A typical example: a customer complains that the felt shrinks so much that the spring is exposed. In fact, the ironing felt did not shrink, but the installation was not firm. The ironing felt fell off during use and continued to run, resulting in the felt material becoming a diamond instead of a rectangle. At this time, the ironing felt had to be replaced.
7) Check the springs frequently. After years of work, they are likely to break and cause damage to the ironing felt.
8) The external hard objects will also cause damage to the felt or spring, such as scissors or the size of the ironed linen is too large or too small than the ironing roller.
2. Chemical reasons:
Symptoms: The strength of the felt is gradually lost and eventually turned into fiber debris
1) Hydrolysis: The typical phenomenon of shortening the life of ironing felt is the destruction of polyester molecules due to the combined action of steam, temperature and time, which is called hydrolysis. Higher humidity and temperature in the sheet or ironing felt can accelerate the degradation of the ironing felt to fiber debris. The method to detect whether the ironing felt has been hydrolyzed is to pierce the ironing felt with a coarse screwdriver. If it is easily pierced, it means that the ironing felt has been hydrolyzed and needs to be replaced immediately, otherwise it can be used continuously. Hydrolysis is very destructive to polyester, and polyester will face hydrolysis damage when it is above 95 degrees. If a modern high-speed feeder is used to feed the ironing machine at a high speed, the steam passing through the polyester ironing felt will be greatly increased than normal, and the life of the ironing felt will be shortened as a result.
An example shows that: at a speed of 18 m/min, the life of a 4000 g/m2 ironing felt is about 3030 hours, but the same machine is changed to a speed of 40 m/min for feeding, and the life is only 1486 hours (almost half shortened) .
In order to reduce hydrolysis damage and prolong the life of polyester ironing felt, it is necessary to do:
i) Check the moisture content of the linen before ironing, and control it below 50-55%.
ii) If you want to increase the output, you must have a special waterproof polyester felt. At the same time, the air volume should be kept above 660L/dm2/min.
iii) Ensure the normal operation of the steam valve and the exhaust fan.
2), chemical hydrolysis: the damage to the hot felt by hydrolysis will be greatly accelerated due to the acidic or alkaline type of the wet sheet. Due to poor water quality, rinsing, bleaching, and squeezing, excess detergent is left in the grooved bed and on the ironing felt, and the acid-base balance will be out of balance. If it is acidic, it will shorten the life of Nomex felt. If it is alkaline, it will shorten the life of polyester ironing felt. So the pH value in the sheets should be as close to 7 as possible and checked frequently.
3) Pyrolysis: Hydrolysis can be combined with pyrolysis to form combined destruction.
* Long-term exposure to high temperature will damage the mechanical strength of polyester fiber,
Especially when the temperature of the last roll of a multi-roll ironer is too high.
* The steam temperature and pressure of polyester ironing felt should be less than 6/7 bars (up to 160°)
Otherwise, Nomex (aramid) ironing felt should be used. (Use temperature 160-180°/180°-240°)
Ways to reduce the occurrence of pyrolysis:
① Raise the ironing roller when it is not working;
②Increase output by shortening the feeding interval between sheets and reduce the direct contact between the hot felt and the hot trough bed.
NOTE: If both chemical and mechanical problems exist, the life of the ironing felt will only last a few weeks!