sleepers or ties are an important part of railroad construction. So the Railway sleepers manufacturing process involves a few important steps.
The manufacturing of railway sleepers seems to be complicated due to the equipment used at factory but the actual process is quite simple if we understand it properly.
Now, let us discuss different types of sleepers manufacturing process.
Railway sleepers manufacturing process
In this article, we will discuss the following
- concrete sleepers
- Iron or steel sleepers
- Timber or wooden sleepers
Note: As concrete sleepers are important we will discuss in detail step by step and a brief explanation of remaining sleepers
concrete sleepers manufacturing process
concrete sleepers were introduced in the late 1890s but in India, these are manufactured and laid from 1982.
Concrete sleepers are of two types monoblock and twin block concrete sleepers.
But mostly we prefer Monoblock sleepers,
In the railway sleepers manufacturing process, concrete sleepers are mostly used. So it is very important to know the steps involved in this type of sleeper.
The manufacturing of concrete sleepers is similar to pre-stressed concrete units manufacturing.
watch the video: What is Prestressed concrete? Pre tensioning and Post-tensioning?
Preparing molds
The initial stage of production of sleepers is to make ready molds,
If you are manufacturing sleepers for the first time you have to make the molds into required shapes and sizes.
When you have a full-size manufacturing unit, you can re-use molds for the production of sleepers.
First clean and ready molds that are used for the casting of concrete. Lubrication is done on the inner sides of molds, so this reduces or avoids sticky action of concrete towards molds.
Pre-tensioning of strands
After cleaning and lubrication of molds,
Strands or cables are cut into the required shape and inserted into the molds. These strands are fixed at both ends using anchors.
Now, these strands are tensioned using a hydraulic jack, then anchors are tightened.
Concreting
Concrete is premixed and poured into the molds, then table vibrators are used for proper compaction of concrete and to fill the required shape with even distribution of mix.
This completes the concreting process and shifted to steam curing.
Steam curing :
The molds with the concrete are to be cured in steam for at least 11-12 hours. This technique allows concrete to gain early strength and consistency.
steam chart for curing process :
| Period | Temperature | Time |
|---|---|---|
| Presteaming | 30°C | 2 hours |
| Rising period | 70°C | 2 hours ( 20°C rise per hr) |
| Constant period | 70°C | 4 1⁄2 hours |
| Cooling period | 30°C ( slowly decrease temperature from 70°C ) | 2 1⁄2 hours |
| Total | 11 hours |
Removing molds :
After curing for at least 11 hours you can remove molds for further process.
Using a trench or machinery these molds are removed.
Removal has to be done carefully and separated. These molds can be reused for manufacturing purposes.
Wet Curing
This curing technique is adopted for hydration process and gaining strength of concrete.
After removing molds sleepers are shifted to curing tanks which contains water.
Now, these are kept for a minimum of 14 days period for the overall gaining of strength and durability of concrete.
Testing and transportation
These sleepers are tested for dimensions and moment of failure.
Testing is to be done for at least 1 in every 250 manufactured units.
After testing the sleepers, finishings have to be done by putting numbers and paint on the side surfaces
Also according to gauge length plates are fixed on sleepers.
They are transported to the site and laid.
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wooden sleepers manufacturing process
These are the oldest type of sleepers and the cheapest one. Of course, the maintenance cost is high due to poor environmental resistance.
The process of manufacturing of timber or wooden sleepers is simple. But skilled laborers are necessary for handling wood.
Procedure :
- First wood is cut into required shape and size
- These are tested for moisture content using strips taken out from wood.
- Then the wood is treated in autoclaves and also sterilized for removal of moisture content.
- After getting required shape penetration tests needs to be done.
- Finally, plates are fixed and transported to the actual site.
Iron or steel sleepers manufacturing process
Among all railway sleepers manufacturing process, steel and Iron manufacturing is more costly.
Process
- The steel or iron is taken in a state of liquid.
- Then molds are prepared in the required shape.
- This liquid metal is poured into the molds and cooled for a certain period of time
- Then molds are removed and plates are bolted or welded to the sleepers
- These sleepers are transported to the actual site and laid.
conclusion
From this article, you will be able to know different railway sleepers manufacturing process and their importance.
At the very beginning of railways, timber and wooden sleepers are mostly used then shifted towards Iron and steel sleepers, and finally replaced with concrete sleepers.
Do you know any material in future replaces concrete? Comment below
