Why do we have a hole on the centre of plug of electrical appliances?
DA Danielleaharrison asked on 24 June 2020, 15:46
2 answers / 1024 views / 8 votes
RI
Rinteger 10 p.
Answered 3 years ago
these are the reasons for the holes present in the centre of the plugs
1)contact wipers have bumps on them, these bumps fit in the whole firmly and prevents the plug from slipping out of the socket
2)a plastic tie or padlock is used through the holes to to factory seal the plugs
1)contact wipers have bumps on them, these bumps fit in the whole firmly and prevents the plug from slipping out of the socket
2)a plastic tie or padlock is used through the holes to to factory seal the plugs
SH
Shashihegde 10 p.
Answered 3 years agoIt is a simple but longer answer. bear with me
Let's start with Basic
The plastic parts are produced by a process called Moulding/Molding. It is simply feeding molten plastic in to a cavity in a mechanical assembly called Mould/Mold.
With due its original creators I will use some graphics to make the concepts clear
In above case the molten plastic is injected, hence it is called Injection Moulding.
most of the machines we find works horizontally, so that the molded product falls out of the mould by gravity.
Here is a molding shop for you, Look all of them looks lying horizontally on the floor.
Now, Let's learn the next level.
Do you see any similarity in below products ?
And even this plate. In this case Thin printed sheet of plastic is molded with thicker backing.
Since there is insertion of second product in to moulding, this process is called insert molding.
Our power cord too is insert molded with metal and wire assembly. Before molding it looks some thing like below.
Now, the problem is the mold is horizontal, complete long wire cannot get in to the mold, as ti takes bigger space. Bigger space means bigger machine, bigger machine means lower efficiency, means more cost.
hence the metal plug pins, soldered with the wire and placed in the mold before injecting the plastic to cover it. The pin side need to be secured inside the mould cavity ( Cavity is a opening carved out in a metal plate to make the room , which is negative of the required shape)
The prepared wire assembly need to stay there until the injected plastic solidifies.
Get a feel of my bad drawing skills here.
The Dark blue is the plastic, light blue is metal pins, red one it the wire. In this arrangement inside the mould cavity there is pin to which the wire assembly can be securely hanged. Some what like this. When the insert is small and light it will sit there without much trouble.
Since there is a pin, the plastic does not flow. When the mold opens after few seconds the plastic is solid, but the pin leaves a hole. It is always a round hole, as the round pin is easier to manufacture. ( unless the designer is a fresher or eccentric !)
Finally it comes out like this
Yes, until you know , every hole is a black hole !
Let's start with Basic
The plastic parts are produced by a process called Moulding/Molding. It is simply feeding molten plastic in to a cavity in a mechanical assembly called Mould/Mold.
With due its original creators I will use some graphics to make the concepts clear
In above case the molten plastic is injected, hence it is called Injection Moulding.
most of the machines we find works horizontally, so that the molded product falls out of the mould by gravity.
Here is a molding shop for you, Look all of them looks lying horizontally on the floor.
Now, Let's learn the next level.
Do you see any similarity in below products ?
You are seeing a marriage between plastic and metal, you will find plenty of them around you. If you open the monitor or the Cabinet of your computer, you will find them too. Your automobile filter is insert molded too. Steering wheel has a metal frame inside the plastic covering.
And even this plate. In this case Thin printed sheet of plastic is molded with thicker backing.
Since there is insertion of second product in to moulding, this process is called insert molding.
Oh, yes coming to the point wait.
Our power cord too is insert molded with metal and wire assembly. Before molding it looks some thing like below.
Now, the problem is the mold is horizontal, complete long wire cannot get in to the mold, as ti takes bigger space. Bigger space means bigger machine, bigger machine means lower efficiency, means more cost.
hence the metal plug pins, soldered with the wire and placed in the mold before injecting the plastic to cover it. The pin side need to be secured inside the mould cavity ( Cavity is a opening carved out in a metal plate to make the room , which is negative of the required shape)
The prepared wire assembly need to stay there until the injected plastic solidifies.
Get a feel of my bad drawing skills here.
The Dark blue is the plastic, light blue is metal pins, red one it the wire. In this arrangement inside the mould cavity there is pin to which the wire assembly can be securely hanged. Some what like this. When the insert is small and light it will sit there without much trouble.
Since there is a pin, the plastic does not flow. When the mold opens after few seconds the plastic is solid, but the pin leaves a hole. It is always a round hole, as the round pin is easier to manufacture. ( unless the designer is a fresher or eccentric !)
Finally it comes out like this
Yes, until you know , every hole is a black hole !
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