Cutting Glass Tube And Glass Rod

Glass is a delicate material which is used in manufacturing various things. There are two types of glass like Soda-lime glass and Borosilicate glass. Soda-lime glass can be melted easily at 300-400°C and Borosilicate glass cannot be easily melted and it requires 700-800°C to soften it. Hence Borosilicate glass is used in manufacturing glass apparatus used for laboratory purpose.

Aim:

To know the basic techniques of cutting glass tube and glass rod using a simple process.

Materials Required:

  • 15 cm long Soda-glass tube
  • 15 cm long Soda-glass rod
  • Triangular file
  • Bunsen Burner

Experimental setup:

Procedure:

  • Place the rod or glass tube on the table.
  • Mark the glass tube or rod with triangular file keeping.
  • Keep the triangular file perpendicular to rod or tube and pull it towards you so that a single deep scratch is made.
  • Hold the glass rod or tube with the help of thumbs as shown in the figure
  • Now apply pressure in the direction away from you and try breaking the glass rod or tube.
  • Note: if the glass rod or tube does not break, make a deeper scratch using the triangular file on the mark done earlier.
  • If you see any jagged edge, Trim it by striking with a wire gauge.
  • Gently hold the cut edge of the glass rod or tube in the flame to give a good finish.
  • For fire polishing, hold the edge of glass rod or tube in the bunsen burner and then rotate it back till both the ends get a good finish (smooth and round).

Precautions to be taken during the experiment:

  • Try to make a single deep scratch of required length in a single stroke/attempt.
  • Be cautious while carrying out the filing process and while breaking of the glass tube/rod.
  • Keep your face far and hold the glass tube/rod away with the help of a piece of cloth to get optimum balance.

Frequently Asked Questions on Cutting Glass Tube And Glass Rod

Why glass does not possess a sharp melting point ?

Glass is an amorphous solid crystalline structure having tightly packed molecules. Hence Glass does not possess a sharp melting point.

Why is it required to round off the freshly cut edges of the glass tube or the glass rod ?

The jagged edges might cause injury while handling, hence for the safety and to give good look with a smooth finish, edges of glass tube or rod is rounded off.

Why a glass tube is rotated while heating in a burner ?

To ensure the uniform heating glass tube is rotated while heating.

Which type of glass softens easily ?

soda lime glass

Mention the various steps which are involved in the cutting of a glass tube ?

  • Scratching
  • Breaking
  • Heating the cut edges
  • Cooling

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