Dewatering Machine: In knit fabric finishing process squeezing or dewatering machine is used in case of tube or open form fabric for removing water after dyeing. In case of piece goods fabric hydro-extractor machine is used for water removing. During de-watering process additional chemical is used for soften the fabric. Different types of operational parameters are controlled during dewatering process.
Fig: Squeezer or dewatering machine
Objectives and Functions of Dewatering Machine: Various types of objectives are achieved by the de-watering process. Followings are the main objectives and functions of the dewatering machine.
Excess or remaining water is removed or reduce by the dewatering machine.
In most of the cases, softener is applying during de-watering process.
Apply overfeed to give some compactor.
Process Sequence in Dewatering Machine:
Dyed fabric from trolley
↓
J box
↓
De-twisted
↓
Spreading
↓
Fabrics pass through second padding chamber
↓
Ballooning
↓
Fabrics pass through second padding chamber
↓
Spreading
Working Principle of Dewatering Machine:
After completing the dyeing process from the dyeing machine then the fabrics are ready for de-watering. In de-watering machine tubular fabrics are mainly processed. There is a magnetic sensor which scene the twist of the fabric and its direction and turn the fabric in opposite direction to remove twist automatically. Here dewatering is performed. De-watering is the process to remove the water from the fabric completely by squeezing and it is done by the padder. A suitable expander is used before the fabric is passed through the nip of the padders, which expands the fabric flat wise and adjust the width.
Fig: Passage Diagram of The fabric in Dewatering Machine
The expander width is adjusted as S/J- 20%, PK-25%, Int.-35%, Lacoste-40% wider than the required width. There is a pair of rubber coated padder, where water is removed from fabric when passed through the nip of it.
Normally squeezer contain single or double padders where,
One for removing water and
Other for applying finishing chemicals such as softener.
But this finishing is done only for the tubular fabric. Open widths knitted fabrics are applied finishing treatment later in stenter machine.
Here present the compressor which given compress air to form ballooning before passing through the padder. This balloon remove crease mark but not form the maximum balloon otherwise shrinkage increase.
In feed and out feed traverses which present in albatros control the following functions by over feeding system:
To control the width (dia) of the fabric.
To control the spirality of the fabric.
To control the crease mark of the fabric.
To control the length of the fabric.
Follow the following fabric process routine:
The over stretching depends on these requirements.
Table: Unloading dia from dewatering machine
Item
Un-loading dia from de-watering machine
1×1 Rib
IN DIA + 20 % TO + 30 % OUT DIA
Interlock
IN DIA + 20 % + 30 % OUT DIA
Single jersey
IN DIA + 10 % TO + 20 % OUT DIA
Polo PK
IN DIA + 10 % TO + 15 % OUT DIA
2×1 Rib
IN DIA + 15 % TO + 20 % OUT DIA
Operational Parameters of Dewatering Machine:
Speed: As much as possible (40-60 m/min). Higher the GSM lower the speed.
Over feed: As required. Higher the GSM higher the over feed.
Padder pressure: 3-7 bar as required. Higher the GSM lower the padder pressure.
Width: Fabric width is adjusted as per required width.
Rule of Squeezing Machine or Dewatering Machine:
Twisting not allow in twister
Air must be enough in first and 2nd balloon for all fabrics
System of Single Jersey (S/J):
Dia of squeezer Ring guide 2” larger than dyed fabric.
1st padder pressure 1.5-2 bar and 2nd padder pressure 5-6 bar setting.
Enough over feed for 1-2% compaction.
Delivered fabric 1” large than Required dia.
M/C RPM setting must be 40.
System of 1×1 Rib and Interlock:
Dia of squeezer Ring guide 3-3.5” larger than dyed fabric.
1st padder pressure 1.5 bar and 2nd padder pressure 5 bar setting.
Enough over feed for 1-2% compaction.
Delivered fabric 1.5-2” large than Required dia.
M/C RPM setting must be 50.
System of PK or lacust:
Dia of squeezer Ring guide 2-3” larger than dyed fabric.
1st padder pressure 2 bar and 2nd padder pressure 4 bar setting.
Enough over feed for 2-4% compaction.
Delivered fabric 1.5-2” large than Required dia.
M/C RPM setting must be 30-35.
Calculation of Dewatering Machine:
…………………………..GSM of fabric before J box – GSM of fabric after second padder Extracted water % = —————————————————————————————– x 100 ………………………………………………………GSM of fabric before J box
…………………………GSM of fabric before J box – GSM of fabric after second padder Residual water % = ——————————————————————————————× 100 ………………………………………….GSM of fabric after second padder
Softener take-up %,
….GSM of fabric after second padder – GSM of fabric before second padder × 100
= ———————————————————————————————————————– ……………………………………GSM of fabric before second padder
Founder & Editor of Textile Learner. He is a Textile Consultant, Blogger & Entrepreneur. Mr. Kiron is working as a textile consultant in several local and international companies. He is also a contributor of Wikipedia.
