“Sanforizing Machine” is the Machine used for the sanforizing process. Sanforizing Machine means a machine consisting of a large steam-heated cylinder, an infinite, thick, woolen felt blanket which is in close contact with the cylinder for most of its circumference and an electrically heated shoe pressing the fabric against the blanket while the latter is in stretched condition as it curves around the feed-in roll.
Sanforizing is a mechanical finishing process in which silk fabrics are handled to avoid the natural dimensional alternation between warp and weft. It is also called the method of finishing with antishrinkage. It is a treatment method used primarily for cotton fabrics and also for some other textiles made from natural and synthetic fibers. It is a method of stretching, shrinking, and fixing both the length and width of the woven cloth before cutting and producing to reduce the shrinkage that would otherwise occur after washing.
- The sanforizing method is based on the idea of expanding its outer surface and contracting the inner surface when an elastic felt blanket is passed around a metal roller in contact with it. So the process is called a process of controlled compressive shrinkage.
- The sanforizing method involves stretching and manipulating the fabric until it is washed.
- The fabric is fed into a sanforizing machine during the sanforisation process, where it is treated with water or steam to facilitate shrinkage, then rubbed against a heated rubber band to relax and re-contract the fibers.
- The amount of potential wash shrinkage has to be determined before shrinkage. Following the test procedure, a full-width sample is wash-tested. The compressive shrinkage machine can be adjusted accordingly after the longitudinally and widthwise shrinkage has been determined.
- The fabric is continuously fed into the sanforizing system and moistened therein either with water or steam. A rotating cylinder presses a rubber sleeve against another cylinder, which is heated and rotates. Thus the sleeve is compressed briefly and expanded laterally, relaxing to normal thickness afterward. The fabric to be handled is transported between a rubber sleeve and heated cylinder and is compelled to follow this brief compression and lateral expansion, and relaxation. So, it shrinks.
- The larger the pressure applied to the rubber jacket, the greater the resulting shrinking. The cycle will repeat itself.
The Sanforizing process can be represented in the following schematics below:
- Fabric (F) is moistened by water and/or steam and passes through the skyer (S) or another moisturizing system. This will lubricate the fibers and facilitate the ability to shrink within the fabric.
- The fabric is moistened such that each thread achieves a moisture content of about 15%.
- The above stage gives very little resistance to compression of the fabric.
- When the fabric passes through the expander of the clip (C) we get the appropriate width. The clip expander also transports the fabric to the machine’s most critical part: the rubber belt assembly (specified by arrows in the figure above).
- We see the endless Rubber Belt (R) in the close-up of the above figure. We obtain an elastic stretching of the rubber belt surface by squeezing rubber belt (R) between pressure roll (P) and rubber belt cylinder (RB).
- The more rubber belt we grab, the more stretched the surface becomes. This squeezing point is known as the nip-point or the pressure zone.
- Tissue (F) is now being fed into the pressure field.
- The rubber belt recovers itself after entering the pressure zone and the surface returns to its original length taking the cloth with it. The result of this behavior is a warp yarn shortcoming that brings the filling yarns closer together. Shrinkage occurs at this actual moment.
- The fabric comes into the dryer (D) after compaction within the rubber belt unit. Here the fibers are protected by extracting the moisture from the fabric in their shrunken state.
- A further examination of the fabric is taken after the compressive shrinkage cycle is done. This sample is being wash-tested, too. This test’s final result must meet the Sanforized Standard, in length and width, before it can bear the Sanforized name.
- All Sanforized Licensees have a contractual obligation to follow the test method necessary and meet the requirements set by The Sanforized Company.
Sanforizing Machine Parts
This machine consist of the below mentions parts.
- Entry / Exit J-box
- Infeed roll
- Rubber Belt
- Felt drum
- Felt centering unit
- Delivery roll
- Machine Safety switches
Entry / Exit J-box:
This unit is used to unroll the fabric and store it into the Scray to run the machine continuously. It is consists of a motor controlled by the inverter, compensator, and expender rollers.
The speed of the motor can be controlled by the inverter and the compensator is used to synchronize this unit with the machine. During the running of the machine, press the push button “J-box filling” the speed of J-box drives is increased and J-box will be filled. When we depress the push button “J-box filling”, the speed of J-box down to stoppage. If the minimal fabric contents are falling, the speed of the J-box drive increases the machine speed with the influence of the compensator, and breaking roll is released. We can also see the speed of the J-box on the meter at the operating panel. There is a photocell installed at the J-box which senses the fabric indicates that the J-box contains the fabric or not.
Inlet roll transfers the fabric from J-box to rubber belt. It is consists of motor, inverter, and compensator. The speed of the motor synchronized with the machine rubber belt.
This is the main part of the machine. It is consists of the heavy motor, inverter, safety limit switches. To run this motor we first select the rubber belt and then press the ON push button. The speed of the belt motor is increased or decreased by the push buttons at the operating panel. The speed of the machine is shown on display at the operating panel. There are a safety limit switches installed at both sides ( left & Right). If the belt crosses the right or left limits then the limit switch is activated and the machine will be stopped to protect the belt.
It is consists of a motor, inverter, felt centering device, safety limit switches, and compensator. The motor speed controlled by the inverter and synchronized with the help of a compensator. The speed of the felt depends on the speed of the rubber belt.
To control the shrinkage of the fabric, there is a shrinkage meter and by the adjustment of this POT we achieved the required shrinkage and we can see it on the digital meter in terms of percentage. The analog ammeter is also mounted on the operating panel, showing the current tension. There is an additional option by which we can bypass the compensator with the help of the selector switch at the operating panel in case of the overfeeding process. To protect the felt for any damage, there are two limit switches installed on both sides (left & right).
Felt centering device:
To control the movement of the felt there is a centering guide roller that changes its position with the help of guiding motor. This motor is controlled by the limit switches which sense the felt position and makes the contact to run the guiding motor clockwise and counterclockwise, according to the position.
This unit gets the fabric from the exit J-box and passes it to the winder or plaiter. It is consists of a motor, inverter, and hand POT. The selector switch is used to select it at the operating panel and other exit operating panels. The speed of the roll is synchronized to the rubber belt.
Plaiter / Winder:
This unit coupled with the delivery roll with the help of a chain and clutch. There is a separate clutch for the plaiter and winder. The selector switch for the plaiter and winder in placed at the exit operating panel. Both clutches are operated with the 24VDC power supply.
Rubber Belt Grinding unit
This unit is installed before the rubber belt and used for the grinding of the rubber belt. The motor is coupled with the grinding roll by the gears. This is a single-speed motor and power connection is in star-delta fashion. The controlling panel of the grinding unit is installed near the rubber belt and we can turn it ON and OFF from the selector switch at this panel.
All the inverters communicate with each other with the help of the CAN communication system. There is a CAN communication system installed in the electrical panel which controls the speed of the machine, shrinkage percentage, and inverter frequencies control.