Glass Installer and Manufacturer Resource

How Does Glass Tempering Work?

Dec 5, 2019 4:29:12 PM / by Greg Martell

how does glass tempering work?

As those in the commercial and residential construction industry already know, tempered glass is the strongest type of glass that can be used. Basically, tempering means to heat the glass to extreme temperatures, and then rapidly put it through a high-pressure cooling process. 

This procedure puts stress on the glass, which in turn produces tension that begins in the center of the piece and spreads out. The tension is then compressed on the outer edges, which gives the piece its strength. 

Let’s take a “behind the scenes” look at the five-step process used to produce tempered glass.


The Process of Glass Tempering

After a piece of glass has been fabricated, it is ready to be tempered. 

The following steps are used in the tempering process:

  1. Cutting
  2. Inspection
  3. Removal of contaminants and rough edges
  4. Extreme heating
  5. Rapid cooling

Here is a closer look at each step and their unique purpose. 

STEP ONE: Glass is cut into the desired shape.

cutting tempered glass

The first step is to cut the glass into the desired shape. Fabrication operations such as edging or etching must be completed before tempering, or the strength of final process could be compromised.

STEP TWO: The glass is inspected.

tempered glass inspection

Tempering is an extreme temperature process, so the piece of glass itself needs to be free of any defects which could weaken it structurally. 

A trained inspector carefully inspects the glass for any bubbles or cracks that may prevent the glass from being tempered.

STEP THREE: Contaminants and rough edges are removed.

tempering glass grinding

Sandpaper or a gentle abrasive is used to remove any sharp edges from the glass. There is a variety of grinding and fabrication work that can take place during this step, including selecting from a variety of edgework styles.

The piece is then thoroughly washed to remove any remaining grains of glass produced during this process, and any other specks of dirt that could weaken the final temper.

STEP FOUR:  The glass is heated to an extreme temperature. 

tempered glass extreme heating

Glass is fed into a tempering oven, either in batches or as part of a continuous feed process. The industry standard temperature for a tempering over is 620° Celsius, or 1,148° Fahrenheit.

STEP FIVE: Rapid cooling, or quenching.

tempered glass extreme cooling

The glass then undergoes a rapid-fire, high-pressure cooling procedure. This lasts just seconds, as air blasts from a precisely-placed array of nozzles quickly cool the outer surfaces of the glass. 

As the center cools, it tries to pull back, which leaves it in tension, while the outer surface is in compression. This dichotomy is what gives tempered glass its impressive strength.

NOTE: Another possible process is called chemical tempering, but it is more expensive than the traditional heating and cooling procedure. Here, various chemicals are applied to the glass in order to create an exchange of ions on its surface which will create the needed compression. New Angle Beveling does not offer this service. 

The Benefits of Glass Tempering

After tempering is complete, the glass then receives a final quality inspection before delivery to the customer. Many benefits can be realized from tempered glass, including:

  • Strength: The process makes tempered glass four to five times stronger than non-tempered pieces of glass, because glass in tension breaks about five times more easily than it does in compression.

  • Flexibility: Tempered glass can be cut into many different shapes, sizes and patterns.

  • Beauty: Additional beauty can be added to tempered glass through beveling, polishing or v-grooving.

  • Safety: If it should somehow manage to shatter, tempered glass uniquely breaks into small, less-jagged pieces instead of dangerous glass shards.

  • Applications: The non-shatter element makes tempered glass perfect for applications with high use, where a traditional break could cause serious injury. This might include shower enclosures, doors, walls, railings, outdoor furniture, indoor furniture, display cases, office walls, and lighting fixtures.

A skilled glass vendor using modern technology and state-of-the-art machinery can produce custom, high-quality tempered glass pieces that are perfect for many applications.

Glass Tempering 101 Infographic Guide. Click to Learn More.

 

Topics: Tempered Glass, Glass Edgework

Written by Greg Martell