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					Dankotuwa Porcelain PLC                                               Sagger and NBC plant

Time period: 31st of January 2011 to 05th of February 2011

Objective: Familiarize with the processes of saggers and NBC department

Working hours: Sagger - 7.30 to 16.30

                    NBC kiln – 06.00 – 14.00, 14.00 – 22.00, 22.00 – 06.00

Capacities:     Sagger bases - 250 – 350 pieces per day

                NBC kiln – 1500 pieces per day

Number of Employees: 35

Inputs: For saggers and bases – raw materials
          For cookware – pug rolls
          For NBC ware – pug rolls, glaze and biscuit ware
          For NBC kiln – glazed NBC items loaded cars


Outputs: Saggers and Sagger bases
           NBC ware
           Cook ware




1. Introduction

   The Saggers/NBC plant manufactures saggers, sagger bases, cook ware and New Bone China
(NBC) items glazing and firing. Saggers and sagger bases are made by powder pressing.


   1.1.      Main raw materials for sagger and base production
                         Japanese ball clay (JBC)
                         English ball clay (EBC)
                         Silimanite
                         Mullite
                         Aluminum oxide (Alumina)
                         Cordierite
                         Grog powder
                         Talc




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Dankotuwa Porcelain PLC                                           Sagger and NBC plant


2. Process Flowchart for NBC
          Flow Chart                     Operation Name                Monitoring and
                                                                   controlling parameter
                          (1) Moulds from Mould Department.       Damages and height of
                                                                  Moulds
                          (2) Pug rolls from preparation          Diameter, Volume of
                          department                              trapped air, Hardness
                          (3) Forming                             Thickness, Green
                                                                  product weight,
                                                                  Foot diameter
                          (4) Drying                              Temperature
                          (5) Green ware finishing and            Damages, weight
                          inspection
                          (6) finished green ware transport to
                          biscuit kiln
                          (7) Biscuit firing                      Temperature
                          (8) fired biscuit transporting to the
                          NBC plant
                          (9) large flatware, cups and casting
                          items receive from biscuit
                          department
                          (10) Biscuit inspection and finishing   Damages
                          (11) Glaze received from preparation    Density, viscosity
                          department
                          (12) Glazing                            Dipping time, damages
                          (13) Loading
                          (14) Firing                             Firing time, Firing curve
                                                                  and temperature
                          (15) Unloading
                          (16) Inspection                         Defects and
                                                                  grading




           16


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           16
Dankotuwa Porcelain PLC                                                Sagger and NBC plant


Process flowchart for saggers and sagger bases manufacturing

                             Operation Name                             Monitoring
                                                                        characteristics
                                1. Raw materials                        Type of raw material
                                2. Raw materials                        Type of raw material
                                3. Crushing                             Size of lump
                                4. Mixing of raw materials              Percentage     of    raw
                                                                        materials
                                5. Ageing of the body mixture           Ageing time
           5
                                6. Inspecting the body mixture          Moisture content
                                7. Information from planning
                                    dept.

                               8. Pressing                              Pressing pressure
          Name of     Monitoring
                               9. Drying                                Temepreture and time
          operation   characteristic
                               10. Inspection of green ware             Damages
          Raw         Type   of 11. Firing
                                 raw                                    Temperature
          materials   materials 12. Unloading
                                13. Inspection        and    pouring    Damages, thickness of
                                    setter materials                    setter and quality

           5                    14. Shaping
                                15. Raw materials for N8                Quality
                                16. Preparing of N8                     Percentage     of    raw
                                                                        materials
                                17. Raw materials for sagger            Quality
                                    glaze
                                18. Preparing of sagger glaze           Percentage     of    raw
                                    mixture                             materials
                                19. Sending sample to QA dept.
                                20. Applying     N8    and   sagger
                                    glaze
                                21. Drying                              Temperature
                                22. Finishing                           damages




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Dankotuwa Porcelain PLC                                                Sagger and NBC plant


3. Technical terms and Important things

               NBC (New Bone China) is the technical term used for ivory. These types of items
have an off white color, high translucency and weight less than the normal porcelain items. The
production processes of the NBC items are very much similar to that of the normal porcelain
items. One difference in the manufacturing of ivory items is that they undergo oxidation firing
while the normal porcelain is fired at a reduction atmosphere.

               Saggers are item made to carry the glazed flatwares in the glost kiln. The main
property of these is its ability to withstand very high temperatures (the Glost kiln operates at
about 1330 0C and this is enough to melt the glaze and fire the porcelain item but not saggers).




     3.1.    Sagger formula


 Raw material                                    %
 J.B.C.                                          13
 Mullite (1-2mm)                                 22
 Sillimanite (Japan)                             8
 E.B.C.                                          13
 Cordierite (1-2mm)                              22
 Grogs Large (1-2mm)                             8
 Aluminium oxide (Grade -B)                      11
 Talc(Fired talc powder)                         3


     3.2.    Sagger base formula


 Raw material                                    %
 J.B.C                                           20
 E.B.C                                           10
 Cordierite  (1-2mm)                             15
 Grogs powder                                    20
 Grogs Large (1-2mm)                             35




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Dankotuwa Porcelain PLC                       Sagger and NBC plant

    3.3.   Base body bricks formula


Raw material                          %
J.B.C                                 15
E.B.C                                 15
Sodust                                7.5
Cordierite (1-2mm)                    15
Grogs powder                          15
Grogs Large (1-2mm)                   40



    3.4.   Fire bricks formula


Raw material                          %
E.B.C                                 40
Sawdust                               35
Grogs powder                          60



    3.5.   N8 body formula



Raw materials                         %
J.B.C                                  3
Aluminium oxide (Grade -B)            66
Meetiayagoda ( Fired Powder)          31



    3.6.   Setter material formula


Raw materials                         %
J.B.C                                  4
Cordierite (powder)                   15
Aluminium oxide (Grade -B)             5
Grogs powder                          70
Meetiayagoda ( Fired Powder)           6



    3.7.   Sagger glaze formula


Raw materials                         %
Meetiayagoda ( Fired Powder)          10.52
Grogs powder                          63.15
Dolermite                              5.26
Meetiayagoda (Green ware)             21.05

                                                                 5
Dankotuwa Porcelain PLC                                                 Sagger and NBC plant

   3.8.      Batt body formula


Raw materials                                    %
E.B.C                                            28
Cordierite (powder)                              18
Aluminium oxide (Grade -B)                       10
Gogs powder                                      44



4.0. Suggestions

   NBC plant is needed to move near the biscuit kiln. Transporting biscuit ware and green
        ware is not suited. because,
               Products can be damaged by transporting
               Transporting time and extra cost for the transporting
               When the items are transported iron particles and other impurities can be
                absorbed to the product.
   An awareness program is proposed for the supervisors on theoretical knowledge of the
        saggers/sagger bases manufacturing process.
   A quality manuals system should be prepared for this department.




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