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10.1 Annual requirement of cocoons

The target of raw silk production in a year should be planned in order to determine the size of the reeling factory. The scale of the factory is also influenced by the properties of raw material cocoons because each has different raw silk yieldability. An exact survey of cocoon quality is required before reaching a decision. Generally, the number and scale of reeling machines for installation is derived from the daily target of raw silk production, which is calculated by dividing the annual target of raw silk production by 300 working days per year.

In this example, the raw silk yield from fresh cocoons is considered for two species. The raw silk percentage of fresh bivoltine cocoons is applied in Japan and the Republic of Korea, while the Renditta of multivoltine ratio of fresh cocoons required for producing 1 kg of raw silk is used in India, Pakistan and Sri Lanka. In the case of 60 000 kg of annual raw silk production, the required amount of fresh cocoons is as follows:

As can be seen from the above, the scale of the reeling factory should be differentiated by the raw silk percentage of the cocoon. To summarize, cocoon drying facilities are less useful in tropical countries as fresh cocoon production continues all year round. Temperate Zone countries can only rear silkworms twice or three times a year.

10.2 Equipment for installation

The proper equipment for installation has to be selected by considering the following factors:

  1. Properties of cocoons to be provided
  2. Length of cocoon filament, length of unbroken filament, size and weight of single cocoon filament, percentage of eliminated cocoons, percentage of cocoon shell and raw silk percentage.

  3. Supply conditions of fresh cocoon
  1. Supply times per year of fresh cocoon.
  2. Distance, road conditions, vehicle and containers for transportation of fresh cocoons.
  3. Quality distribution of fresh cocoons with different crop seasons and production sites.
  4. The proper kind and capacity of dryer, adaptable method of cocoon storage, size of cocoon storage room and space for fresh cocoon preparation can be decided based on conditions a to c.

10.3 Location and space

  1. Location. The location of the silk reeling factory should be chosen by evaluating availability of reeling water sources, manpower, electricity and transportation. Ideally, the factory will be sited on a slight hill near a good water supply with adequate drainage, near a densely populated region. The main building of the factory is usually in an east/west direction.
  2. Building site. Space for the building site should be procured to minimize the fixed capital and management costs associated with the idle land, unless future expansion is planned at the same location. Most facilities offer sleeping quarters for two shift operations and refreshment for the workers to increase productivity.

10.4 Quality and quantity of filature water

As water has a major impact on raw silk yield, it is recommended that the factory have access to well water and surface water sources. Quality and quantity of available reeling water is the most important factor in choosing location.

If a site near well water is considered, pumping trials should be conducted over a two-week period during the dry season.

Remember that the amount of reeling water required for production of 1 m/t of raw silk is 1 000 m/t in the Multi-ends reeling machine and 800 m/t in that of the Automatic reeling machine.

10.5 Selection of proper equipment

1)       Drying machine

  1. Chamber dryer or cabinet dryer. The delivery and feeding of fresh cocoons to the dryer is carried out manually. Only this type of dryer can execute a small production of fresh cocoons.
  2. Hot air dryer

The Multi-step type, equipped with an endless chain connected by a wire net is classified into Six, Eight and Ten steps. (More steps need less space for installation.) This type of dryer is vertically divided into three sections: upper, middle and lower each having a different temperature. This type is suitable for a large-scale reeling factory, which has a drying capacity of 5 000 to 18 000 kg of fresh cocoons per 24 hours.

This type has one band of cocoon feeding wire net which carries at least one foot of cocoon piling height for drying, while the Multi-step does only 5 cm of cocoon piling height on the cocoon feeding wire net. There is no difference in the drying capacity between both Multi-step and One-band types. The latter needs less space for installation, but it consumes more electrical power for the drying operation.

  1. Low temperature dryer. This dryer has a dual purpose of cocoon drying and storage. A continuous supply of fresh cocoons is needed for completion of one operation. More attention should be given to the operation of the dryer, especially temperature control.

2)       Sorting machine

A small-scale reeling factory is equipped with a simple type of sorting table. A large-scale factory is equipped with a conveyor or system attached to the sorting machine.

3)       Cooking machine

The proper capacity of the cooking machine should be selected, since most cooking machines are basically the same in structure. In addition, the devices for aiding the pre-treatment part and cooking control parts should be considered for use, depending upon the quality of cocoons, reelability and cocoon shell percentage.

4)       Reeling machine

The reeling machine to be selected usually depends upon the quality of the available cocoons.

  1. Simple reeling machine. This type of reeling machine has five to six ends per basin without the Stop motion device. For this machine, the operator is seated and processes poor quality cocoons. The reeling capacity is in the range of 500 to 600 g per basin per 8 hours.
  2. Multi-ends reeling machine. The Multi-ends reeling machine is equipped with 20 small reels per basin. The groping ends, picking ends and cocoon feeding of reeling thread is done manually with the reelers in a standing position. The reeling capacity of this machine is in the range of 800 to 1 000 g per basin per 8 hours. This equipment may be used with all qualities of cocoons.
  3. Automatic reeling machine. An automatic reeling machine may be used effectively if good quality cocoons with 60 percent reelability, 1 000 m filament length and 20 percent cocoon shell are used. In automatic reeling, the production of raw silk can be increased with less labour, compared to Simple type or Multi-ends type reeling. Note: Mass production can lead to a reduction in raw silk yield. One set of automatic reeling machines usually consists of 400 reels, but 200 reels to 480 reels can adjust the number of reels per set. The capacity of reeling per set is around 30 kg per 400 reels per 8 hours.

5)       Re-reeling machine

The re-reeling machine is composed of large wheels known as "window", which reel five or six skeins per wheel. One window of five skeins wheel has the re-reeling capacity of ten skeins per 8 hours (5 skeins x 2 times = 10 skeins), if one skein weighs around 130 g. It is possible today to find the High-speed re-reeling machines on the market.

6)       By-product treatment machine

On an industrial scale, the reeling factories in excess of 1 000 ends require installation of a by-product treatment machine to separate pupae from parchment layer "reeled out cocoons". This function is done manually in small-scale factories.

7)       Reel permeation device

The reel permeation device "Vacuuming treatment tank" is necessary for the pre-treatment of small reels for the re-reeling process. This device is especially useful for double skein reels, which have over 70 g of raw silk wound on to a reel.

8)       Skein twisting and booking machine

There are two kinds of skein twisting and booking machines. One is the short skein-booking machine by which the skeins are twisted and folded once. Another is the long skein-booking machine by which the skeins are twisted on the turntable and booked without folding.

9)       Raw silk testing equipment

The raw silk testing equipment for quality control in the reeling factory is required as follows:

The Serigraph and Cohesion testing machines are not necessary for reeling factories, but are for quality assurance and research institutions

Table 32. Items of machinery required for a silk reeling factory
(Capacity 70 M/T fresh cocoons yearly)

Types of machines





Cocoon drying machine

Hot air blowing and circulating system, three horizontal sections upper, middle and down rooms with automatic electrical thermostats
L 12 700 x W 5 300 x H 2,000


1 set


600 kg of fresh cocoons per 8 hrs.

Cocoon cooking machine
Endless chain system. No. of baskets : 70
L 8 550 x W 1 190 x H 1,795


200 kg of dried cocoons per 8 hrs.

Cocoon reeling machine
Semi-automatic type with denier detecting system 14 ends per basin
L 16 135 x W 1 360 x H 1 795

32 basins

117 kg of dried cocoons per 8 hrs.
Silk re-reeling machine 5 heads per wheel
L 18 470 x W 1 360 x H 1 360

40 wheels

45 kg of raw silk per 8 hrs.
Vacuum permeation device Power : 1.5 hp
? 750 x H 1 200

1 set

100 kg of raw silk per 8 hrs.
Cocoon assorting machine Conveyor type

1 set

300 kg of dried cocoons
By-product treating machine Automatic type
L 7 880 x W 545 x H 1 000

1 set

30 kg of dried pellete per 8 hrs.
Silk booking machine Motor driven

1 set

Silk skein twisting machine Hand driven

1 set

Seriplane winding machine 20 black boards, carrier and Standard Photos included

1 set

Illumination equipment for inspection For Cleanness and Neatness test

1 set

Denier scale 400 revolution and 200 revolution

2 sets

Sizing reel Circumference of reel 1.125 m

2 sets

Rewinding test machine 10 bobbins

1 set



2 tons
Oil tank  


Water tank  




Electric equipment  


Mechanical tools  




Table 33. Building space required for each item of machinery to be installed


Space (m2)


Cocoon drying


Hot air circulating type : 1 set
Cocoon storage


Honey comb tube type and general room type
Cocoon sorting


Conveyor type sorting machine : 1 set
Cocoon cooking


Auto cocoon cooking machine : 1 set


Semi-automatic reeling machine : 32 basins


Re-reeling machine "32 wheels
Inspection and finishing


Seriplane winding machine, illuminating equipment and rewinding test machine
By-product treating


Auto by-product treating machine : 1 set
By-product storage




Boiler 1 set (2 tons)


Tools and spare parts
Raw silk storage









1,255 m2



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