Tea is manufacturing using green leafs. Basically there are three varieties of Tea industry. Based on the height from the sea level to tea estate there are 3 regions has been identified.
Since we are in the “Low Grown Tea” range, we would like to share our knowledge regarding Manufacturing of Low Grown tea.
Two leaves and a bud is known as Green leaf. In our factory we use green leaf plucked from our very own tea estates and also gereen leafs collected from our neighbor planters. Some planters directly send green leafs to our factory themselves while some planters are sending green leafs to our collection centre in our shopping complex in Pitigala town centre. And also some of our planters handed over their green leaf to our collection trucks which are known as Lines. These Lines are function on schedule and we have been maintaining several Lines providing our suppliers much comfort.
Regardless of the way we get green leaf to factory, we do weighing first of all.
Green leafs are stored in plastic boxes which have capacity of 16 to 18 kg. Storing in these boxes reduces the wastages and over fermenting.
After weighing green leaf boxes send to the Loft. Loft is an area which has wooden floor. Our loft is in the first floor.
So we use Leaf Elevator to bring those boxes to Loft.
In the loft we categorized these green leafs in to 3 grades according to the following standards. This process is known as “Leaf counting”.
There should be 60 % to 80% of B grade among the collected green leafs, to have good tea product after all.
After taking leaf count, green leafs are spread on the Troughs for Withering. As we have to spread according to Trough's capacity weighing has to be done again. Green leafs are spread on the trough with the density of 2.5kg to 2.75 kg per square feet.
Afterwards, we start trough Fan. (Fan starter - Isolator use to turn on and off) It pushes huge air flow and this air flow goes through green leafs in trough. We push cool and /or hot air depending on the weather conditions. Can be changed the temperature of the wind we push, using Fans. This 48” fan has 960 RPM (Rotation per minute) motor and has an ability to push 9 CFM (Cubic feet per minute) air. We use hydrometers to see what is happening to green leafs. Hydrometer has two scales. One is known as Wet bulb and other is known as Dry Bulb. Difference between Wet and Dry bulbs means us a lot. In this case, withering, there should have 6 degrees difference between wet and dry bulbs. This process takes 4 to 6 hours. And then check the hydrometer’s difference is 6 degrees or not. It is not, we loose them and let the green leafs to wither further 6 to 8 hours.
This process removes 42% to 46% of moisture in the green leaf. Afterwards we take Leaf Count again.
Now withering is done. Since there may be some dust particles and unwanted things, withered green leaf should be cleaned. We send withered green leafs to Withered Green Leaf Shifter for cleaning. Then have to measure what we have now. So we are weighing the Withered Green Leafs.
Rollers are installed in the ground floor. As you see they are big and strong machineries. We send withered green leafs to Rollers. This is called charging rollers. This picture shows the process of charging withered green leafs to a Roller. Capacity is depending on the Roller modal. Our factory is using automated process form rollers. (Earlier we had separate machineries but since automated system provides us quality improvements, speed up the whole process, accurate timing, low wastage and minimal labor cost, we have moved to automated system.)
We have to maintain acceptable humidity in the rolling room. So we spray water around the Rolling room. It helps oxidizing properly. In the rollers, withered green leaf breaks apart and starts oxidizing.
We let withered green leafs to roll about 20 minutes in the rollers and unload the stuff. In the rollers there should be room temperature of 80F to 85F. So we need to cool the stuff.
When the rollers are operation green leafs are gathered as balls and we have to break those gathered balls apart. And also we need to separate leaf particles which are broken in to small enough particles. In order to accomplish these tasks we put rolled stuff in to Roll Breaker. In the Roll Breaker it cools the leafs, break apart gathered balls and separate small particles – doles.
All the doles and Big Bulks from Rolling Breaker send to Fermenting Area.
Fermenting area is a humidity controlled room. We keep the doles and Big Bulk to oxidizing for 2 hours to 2.30 hours. The Hydrometer difference should be below 3 degrees. When spreading for oxidizing that layer should have standard thickness.
For doles thickness should be 1.5 inch to 2 inch and for Big Bulk thickness should be 4 inch to 6 inch.
We must stop oxidizing after 2.30 hours. To stop oxidizing we put them in to Drier.
There are two types of driers available.
When we use E.C.P. Drier, its inlet temperature is 210F and out let temperature is 130F.
If we use F.B.D., its inlet temperature is 260F and outlet Temperature is 195F.
When we fill properly oxidized doles and Big Bulk in to drier we keep them 19 minutes to 21 minutes in the drier. When the time we unload the stuff its moisture content dropped till 2.8% - 3%. What we have from the drier’s outlet mouth is Black tea.
(this window separates humidity controlled area from drier area. Fermanted leafs sends to drier via this window.)
In another word we have finished making Black tea.
With Black tea we are going to remove fibre and stalk, grading, and finally packing.
First step is to remove fibre which comes with black tea. We use Fibre Mat to separate fibre from good tea. Fibre Mat has rollers (Cylinders) and they are rotating when the machine is working. In one side there is a unit with Felt Packing and it touches the roller. This action generates Static Electricity. The black tea which we taken from the drier mouth is go through the fibre mat. Fibre contains much moisture as its nature than Black tea. The rollers are charged with static electricity and due to static electricity, the rollers grab that fibre with much moisture content. What we have through Fibre mat is fibre free Black tea.
Then we send the Black tea through 3T Stalk Extractor. This equipment has rotating cylinders which has more static electricity generated using DC voltage. As its huge power of static electricity this 3T Stalk Extractor grabs stalks productively. Now we have done removing stalks also.
Then we send the Black tea to another equipment, which was used as a stalk extractor, sometimes ago. But today we use it as a filter which separates black tea by sizes. This machine is called Middleton Stalk Extractor.
Middleton Stalk Extractor has 3 trays.
What comes out from these trays sends to Chota Shifter and MICHI Shifter. Here when passing through these shifters grading is done. The following chart shows the pathway of filtering and grading of tea in Chota shifter and MICHI Shifter.
Chota Shifter is also known as Rotary Shifter. This shifter has several filters. The number indicates number of halls per length of single inch. Low number means big halls and high number is small halls.
The stuff come out from the No. 4 of MICHI Shifter sends to Terriniper for break into small doles again.
Now we are in a last filtering process. In this stage we are going to remove stalk using Colour separator. Colour separator has sensors which could identify stalk using its colour. These colour separators use advance technology and are very valuable machineries. The following types of tea having stalks and has to be removed. Therefor we send them through Colour Separator.
FBOP 1, FBOP, BOP1, OP1, OP, OPA, PEKOE, PEKOE 1
This is the final stage of Tea grading. Now we have to remove unwanted particles. So we use Suction Winnower. unwanted particles collected to dust collectors.
Now tea manufacturing process is over. We send the total out come to the Bulking Chamber in packing section. In the bulking chamber maintain separate stocks of each kind of tea. When we have enough stock we start packing. According to the packing density we decide number of tea packs per load. There are standard number of packs per load .10 packs, 15 packs, 20 packs, 30 packs and 40 packs. It exceeds 40 packs the next number of pack should be 60. Likewise there should be increment of 20. (ex. 60 packs, 80 packs, 100packs)
Ready to go. Invoicing under selling mark (Brand name), and send to Colombo Auction through broker.
For our drier we need firewoods. We have to split firewoods into relevent sizes which suitable for driers.
You can view our factory layout from here. Please click here.