Category

Theme images by Storman. Powered by Blogger.
Best viewed in Google Chrome

Kilns & Furnace related ...

Labels

Labels

Raw Materials related ...

Advertisement

Popular Posts

Services

Showing posts with label Production. Show all posts
Showing posts with label Production. Show all posts

Quality Assurance during Green Production of Refractory Bricks

- No comments

Quality is defined as what the customer wants in a product (here ‘Refractory’), not just meeting specifications but also ensures customer delight. Consistently achieving the specifications without failure is one of the most important requisites for Quality. Then, a question automatically arises that how can one be effectively consistent in any regular operation. The answer is: one has to plan and follow some Standard Operating Procedures or SOPs, a term more popular among Quality Circles. Standards promote good work habits among all levels of the organization. To standardize is to choose the best method and promote consistency which is essential for quality.
Operator running a Friction Screw Press (FSP) image
Fig.- Operator Running a Friction Screw Press (FSP)
There has to be SOPs for each and every operation starting from raw material testing, acceptance to brick dispatch in a refractory plant. But merely having SOPs will not help in any respect except for showing them to any customer, if such a situation arises! However, following these SOPs religiously will not only benefit in getting the quality in various refractory products but also, help in increasing the productivity and reducing the rejection percentage at every level thus, ultimately bringing down the cost of production.

An array of Friction Screw Presses in a Refractory Plant image
Fig.- An Array of Friction Screw Presses in a Refractory Plant

Nevertheless this article is not to discuss the advantages of SOPs or Standardization which will be discussed in a separate post. Here our point of discussion is how to ensure quality in a refractory brick during its green production. For this each and every brick must pass through a process of checking as a part of standard procedure in the process of production. Below is a list of such things (parameters) that have to be checked during green production of refractory bricks as a criterion for their acceptance or before sending them to drier.


GREEN BRICKS CHECKING LIST
1. Size and critical Dimensions as per actual & shrinkage given in the Production Programme (Refer Drawing if required).
2. Quality / Plate mark / Special instructions.
3. Right angle, Centre slope.
4. Warpage, Bulging.
5. Die Plate jam, cleaning.
6. Spongy, Texture.
7. Rags, Corner loose.
8. Lamination, Crack (Hammering).
9. De-airing & Pressing stroke (Set-up approval).
10. Green B.D, Refractory Composition.
11. Sieve analysis report of Powder (Mixture).
12. Free iron in the Powder/Mixrure.

Green BD (Bulk Density), Burned BD and Moisture Content of Green Mixture (Powder) of Alumina Refractory Bricks

- No comments

Before going into large scale production of any product, based on their R&D work and the results obtained from pilot scale production laboratory has to fix certain parameters (recipe of production for that product) and provide it to the production department which the latter will follow in order to meet the required specifications and quality of that product. Two such important parameters required for manufacturing any type of refractory bricks are the ‘Moisture content’ of the green mixture (powder) and ‘Green BD’. Here our focus will be on the practical aspects of these two parameters of refractory bricks particularly those containing various percentages of alumina (Al2O3%). 

The amount of moisture or water present in the green mixture (powder) of alumina containing refractory bricks help in green binding and also add plasticity. But beyond a certain percentage, water or moisture present in the green mixture of refractory bricks would be harmful leading to an increase the rejection percentage mainly due to -


(i) Increase in porosity and
(ii) Development of radial cracks in refractory bricks.



What should be the maximum percent of moisture, green BDs corresponding to the different values of burned BDs of refractory bricks having different Alumina content (Al2O3%) etc. are given in the following table:

Refractory Bricks (Al2O3%)
Moisture%
Burnt BD
Green BD
Factor (Gr.BD/Br.BD)
40.00
7.00
2.20
2.36
1.073
45.00
6.50
2.25
2.41
1.071
50.00
6.50
2.45
2.62
1.069
60.00
5.50
2.50
2.65
1.060
70.00
5.50
2.60
2.75
1.058
75.00
5.00
2.65
2.78
1.049
80.00
4.50
2.70
2.82
1.044