The Process of Making Cement Asbestos Sheet

Photo: Illustrative image for the 'The Process of Making Cement Asbestos Sheet' page

- the basic methodology of producing the Cement Asbestos has changed little in the last 100 years

by Terry Dash and Tim Gane

***Step5***

1. Cement and reinforcing fibre (originally asbestos) in a 10:1 ratio are mixed with water to form a thick slurry.  Small quantities of other chemicals, eg cellulose is added to aid the manufacture process.

2. This slurry is transferred into a number of stirred vats to maintain the slurry in suspension.

3. A rotating cylinder fitted with a sieve cloth is partially immersed in the vat and picks up a thin layer of cement and fibre gradually builds up as the slurry dewaters through the sieve cloth.

4. A moving belt (Felt) is in contact with the rotating cylinder and picks up the thin primary layers of cement and fibre on the surface of the felt.

5. The application of vacuum to the underside of the felt aids the dewatering process and gradually an ever increasing thickness of material on the felt.

Photo:Step 6 Cross Cut Knives Cut the Wet Sheet to the Required Size

Step 6 Cross Cut Knives Cut the Wet Sheet to the Required Size

Photo courtesy of Linda Clarke

6.When the desired thickness is reached the wet sheet is cut and fed off the belt though a series of cross cut knives where the sheet is cut into the required size.

Photo:Step 7 Depiling - Lifting the Cured Sheets from the Oiled Tins

Step 7 Depiling - Lifting the Cured Sheets from the Oiled Tins

Photo courtesy of Linda Clarke

7. The flat sheets are transferred to an oiled, profiled tin by a pneumatic moulding head and the resultant corrugated sheet is left to cure for 24 hours.  (The tins are oiled to assist with separation after the curing)

Photo:Step 8 Linda Pettit and Steve Manning Handmoulding the Wet Sheet

Step 8 Linda Pettit and Steve Manning Handmoulding the Wet Sheet

Photo courtesy of Linda Clarke

8. Smaller pieces of the cut wet sheet from step 6 are used for hand-moulding.  As the name implies the sheets are hand moulded over preformed glass fibre moulds before being left to cure in the same way as the sheets.

Photo:Step 9 Sorting and Stacking the Finished Sheets

Step 9 Sorting and Stacking the Finished Sheets

Photo courtesy of Linda Clarke

9. After 24 hours in the tins the finished sheets are inspected, wrapped and transported to the stock yard to complete the curing process for 14 days before leaving the site to the customer.

Photo:Step 10 An Example of the Finished Product in the Standard Grey Finish

Step 10 An Example of the Finished Product in the Standard Grey Finish

Photo courtesy of Linda Clarke

10. The standard finished colour is grey but it may be painted either on site or at the factory where water based acrylic paint is spayed onto the preheated (90degC) sheets and hand-moulded products.

Photo:Step 11 Fitting a New Cloth Ready for the Next Batch of Sheets

Step 11 Fitting a New Cloth Ready for the Next Batch of Sheets

Photo courtesy of Linda Clarke

11. Finally the equipment must be washed down, thoroughly cleaned and a new felt cloth fitted ready for the production of a new batch of sheets.

 

 

 

The Products

There are a large range of products made at Meldreth, but the most important are:

Profile 3

A corrugated sheet in a varying range of  sizes but all with a 3 inch   distance from crown to crown. This is used for smaller structures.

Profile 6 or BIG SIX

As the name implies, a corrugated sheet of varying sizes but all with a  6 inch distance from crown to crown.  This is used for larger structures.

Flat Sheet

Used for wall cladding

Handmoulded Goods

Rainwater goods, ventilators, Whaddon tiles, soil goods, bath panels etc. etc.

All of the products come with a 30year guarantee.

Photo:Atlas No 1 Machine ~1929 - 30

Atlas No 1 Machine ~1929 - 30

David Catley

Photo:Atlas No 5 Machine in the late 1960s

Atlas No 5 Machine in the late 1960s

Robert Henry

Photo:Atlas No 5 Machine in the late 1960s. (Alec Watts is in the White Coat and Bill 'Popeye' Stanford is by the Machine)

Atlas No 5 Machine in the late 1960s. (Alec Watts is in the White Coat and Bill 'Popeye' Stanford is by the Machine)

Robert Henry

 

This page was added by Tim Gane on 29/01/2011.

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