Lap Former Machine:
To get quality yarn, I mean combed yarn before combing process lap former machine is used. It is also called combing preparation machine. The lap former has, furthermore, the task of forming the interfacing or lap, which is employed to feed the comber machine. The lap is obtained by doubling a certain number of slivers (from16 to 32) previously subject to a drawing passage. The slivers are fed side by side, passing, through rollers and stop motion. The slivers enter the drafting section and then calendar section to produce a compact lap. Finally the lap is wound on to bobbin. In the lap former, the material under goes a light draft of around 1.5 to 2 times one a drawing aggregate of the type 2 on top of 3 cylinders.
Lap preparation is the important step before combing operation, which influences the quality of the combed sliver. The requirements of the lap for the good performance of combing are good fiber orientation, leading hooks presentation, and uniform thickness. The combers are fed with fiber lap produced by doubling several slivers and webs.
The lap prepared with proper doubling and draft may enhance the uniformity of the output sliver. The lap sheet with higher degree of evenness produces the highly uniform combed sliver. Good fiber orientation in the feed lap along the length of the feed lap is a prerequisite for obtaining better sliver quality. Lap can be produced by different routes as pointed in Figure 2.
Sliver lap former machine and ribbon lap former machine are used to produce the lap by doubling several numbers of slivers and webs, respectively. Another route has sliver doubling machine, also called super lap former machine, used for lap preparation. Route-2 is adopted in the modern lap preparation process. Route-1 is also still in use in many spinning mills. In the route-1, the card slivers in the range of 16–32 numbers are doubled and drafted in the sliver lap machine and the delivered lap sheet is wound onto the cylindrical spool, which is termed as “sliver lap.”
The dimension details of sliver lap are given as follows:
- Lap grams per square meter (GSM) of 50–70 g/m
- Width of 230–300 mm
- Diameter of 500 mm
- Weight of up to 27 kg
The importance of lap preparation is as follows:
- Fibres from carded sliver are not well oriented and may lie in all directions.
- Most of the fibres arc hooked.
- To avoid excessive strain on comber needles.
- To avoid loss of good fibres in the nods.
- To get high degree of evenness in transverse direction.
Features of Lap Former Machine:
- Delivery speed up to 120 mts/min
- Batt weight up to 80 gms/mt
- Pro-In control for lap build-up
- 4/4 spring loaded drafting system
- Integral top roller release
- Variable top roller loading
- Modular construction
- Complete belt drive
- Auto spool changer
- Positively driven creel
- Lap transport through lap trolley
Features of Modern Lap Former Machine:
- Auto doffing for full laps.
- Auto stop motion at sliver breakage, at doffing and lapping.
- Auto grain adjuster.
- Auto leveling.
- Auto lap carrying device.
- Indicator light for faulty location.
- Lap length measuring unit.
Functions or Objectives of Lap Former Machine:
The functions of lap former are as follow.
- Equalizing: To improve evenness of the lap by doubling of slivers
- Parallelizing: To create parallel arrangement of fibres in the lap by drafting of slivers
- Blending: To compensate the raw material variations by the doubling of slivers
- Dust removal: To remove dust within the overall process by suction
- Lap formation: To make lap by calendering
Necessity of Lap Former Machine:
- To reduce the strain to delicate comber reduces.
- To reduce fiber damage.
- To reduce chance of good fibers waste.
- To reduce short fibers.
- To reduce thick and thin places in the sliver.
- To control wastage.
- To parallel and straight of fiber in carded sliver by changing pushing of fibers.
- Not freely opening of fiber from sliver.
Classification or Types of Lap Former Machine:
A. Conventional system
- Sliver lap former machine
- Ribbon lap former machine
B. Modern system
- Super lap former machine
I have already published an article on different types of lap former in spinning process. You can read that article.
Working Principle of Lap Former Machine:
Generally, twenty eight cans of drawn sliver from the first draw frame are placed under the two creel rails of the lap former. Flow of material through the lap former is shown in the Figure 3 Creel rollers withdraw the slivers from the cans and feed to the drafting system. The slivers running into the drafting arrangement are attenuated by a draft of 1.3 to 2.5.
The two webs created by the drafting system pass over two deflecting plates onto the web table. These webs are superimposed or placed one above the other. The calender rollers draw these superimposed webs from the table and compact them to make lap and deliver it to the lap winding assembly. Winding assembly winds the lap on an empty tube. Empty tubes are automatically exchanged when length of the lap is completed.
References:
- Process Management in Spinning by R. Senthil Kumar
- Textile Engineering – An Introduction Edited by Yasir Nawab
- Mechanics and Calculations of Textile Machinery by B. Varadarajan, C. B. Senthil Kumar, and N. Gokarneshan
- Handbook on Cotton Spinning Industry B. Purushothama
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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.
