What Do You Need To Know before Choosing Press Felt? And Solutions To Common Problems

As an important consumable in the paper making industry, press felt can be divided into three categories: top press felt, wet felt and dryer felt according to their uses. They have excellent water filtration properties and are used to filter moisture from paper pulp and stack wet paper from multiple webs.

Press felts are completed through the following operations: warping and winding - weaving - combing - needling - shaping - finishing.

Their lifespan is generally: about 2 months for felts used in toilet paper machines, about 3 months for felts used in cylinder paper machine, and about 35 days for felts used in cultural paper and packaging paper machines.

(1) How to choose press felt?

At present, most press felt are made of needle-punched felts, which have fast dehydration efficiency, low moisture absorption, and no need for singeing.

For paper machines with low speed requirements, the weight can be in the first 730~750, and the gram weight of the upper press felt needs to be 50 grams higher. It can be determined according to the structure and specific gravity of the press felt bottom mesh, the effective power of the paper machine vacuum pump, the washing water pressure and the size of the drying cylinder.

In addition, please note that the press felt specifications can be selected according to the principle of "long rather than short, wide rather than narrow, thin rather than thick".

(2) How to install the purchased press felt?

The front of the press felt is the sizing surface, and the running direction of the press felt on the paper machine should be the arrow on the surface of the press felt. After the press felt is installed, wash it with hot water with 5%-10% sodium hydroxide or detergent. The hot water temperature should be 50℃-60℃. Wash it after idling for 15-20 minutes, and then wait for the press felt to soften completely.

Note: The initial tension of the press felt should not be tight, and the speed should not be too fast. After 2-3 days, the press felt can be tightened and the speed can be increased.

(3) How to deal with the press felt becoming wider after use?

This is a normal phenomenon and should not be torn by hand. Stop the machine and wait for the press felt to dry before cutting off the excess. Then iron the edges with a soldering iron.

(4) What is the situation when the press felt shrinks?

This is mainly due to the loose structure of the base mesh during press felt production. In this case, the press felt tension roller should be loosened to allow the press felt to run in a relaxed state. Incorrect standard lines will affect the normal operation of the press felt.

(5) How to solve the problem of new press felt sticking to the slurry?

The slurry sticking to the new press felt is generally caused by the rough surface. You can use a copper brush to brush it first. The slurry sticking to the press felt after a period of use is caused by the fibers being too long. You can use a blowtorch to burn the fibers.

(6) Can the reverse side of the press felt be used?

Whether the press felt can be used from the back depends on the structure of the press felt. Plain press felts and ordinary press felts can be used from the back, but it is still necessary to pay attention to the fact that the fibers on the front of the press felt should not be too small, otherwise it is easy for impurities to enter and cause embossing. If it is a twill press felt, the back cannot be used.

(7) Why is the press life too short?

It depends on the condition of the felt. Is it because the press felt is not dehydrated well in the later stage of use, or is it because the paper surface is not good or the press felt is worn out? This can be seen from the felt cloth. If the vacuum plate surface is uneven, the material is rough, and the opening is too large, the friction rate of the felt cloth will increase, which will shorten the life of the press felt cloth.