How does a glass knife work, scissors cut glass in water, what principle?

The glass head is sharpened with a large but sharp edge. Cutting a glass knife across the surface of the glass leaves a groove on the glass with a sharp bottom. Then this side of the glass groove is tensile, because the bottom of the groove is very sharp, there is a large stress concentration, and the brittle material glass is easy to crack along this groove.

A glass knife is a tool used to cut glass, usually the part of the glass knife used to cut is made of diamond or alloy material that is harder than glass, and this part is on the tip of the knife.

The glass knife can be divided into diamond glass knife and alloy roller glass knife, which is suitable for cutting flat glass with a thickness of 1-8 mm, and is an indispensable glass cutting tool for decoration and building materials industry.

The head of the glass knife is the key part of the glass knife, and the head of the glass knife determines the cutting quality of the glass knife. The cutter head is sharpened with a large angle and a sharp edge. When the glass knife cuts through the surface of the glass, the blade leaves a groove in the glass with a sharp bottom.

This side of the glass groove is tensile and the bottom of the groove is very sharp and the stress concentration is large, so the glass made of brittle material is easy to crack along this groove.

How to use the glass knife:

The operator first has to fix the size with the ruler, hold the ruler with his hand, and use the glass knife to draw all the way along the ruler, and need to use force, you have to feel the sound of cutting through the glass skin, if you feel that there is no sound when you scratch, that is, you don't use enough strength, you need to stroke again. When the lines are drawn, place the glass knife and place the grooved edge of the glass against the table. Wear gloves to pay attention to your own safety, facing the marks of glass scratches, press the palms of both hands on both sides of the scratches, and close to the average position of the edge of the glass, and then use force on the palms of both hands at the same time, to be fast enough, fast enough not to force slowly.

When you hear a bang, you have to retract your strength immediately to prevent your hands from pressing the separated glass against the table and causing it to break. Finally, the edge of the glass crack is tossed with a sanding cloth, and the throwing is not too sharp.

Thin glass pieces can be cut more neatly and effortlessly when placed in deep water with good scissors, because under the pressure of water up and down, the glass is easier to soften than in the air, the surface tension of the glass is reduced by the influence of polar water molecules, and the attraction of positive and negative charges between the surface of the glass and the water molecules increases, so it can be cut easily.

Glass can be thought of as a network of tetrahedral basic units strung together. This mesh structure can be torn apart by external force, and the external water can accelerate the rupture of this mesh structure: when the glass is placed in water, water molecules can be adsorbed at the tip of the glass crack and decompose the reaction, thus accelerating the expansion of the glass crack.

. I did this in 1980 when I was in elementary school. Put water in the washbasin, and ordinary scissors can easily cut through the glass. It should be in the water, which can absorb the high-frequency vibrations of the glass breakage, thus reducing the occurrence of chipping. Ask for expert advice.