Glass Tempering

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Production Capabilities in Glass Tempering

TOUGHENED GLASS ESG

Toughened glass is safety glass. It is denoted by the acronym ESG (from German, Einscheiben Sicherheitsglas). It features higher elasticity, mechanical, and thermal strength compared to annealed float glass; it is safer because when broken, it shatters into small, non-sharp fragments.

Tempering glass involves heating it to a high temperature (620-680°C) and rapidly cooling it in a stream of compressed air. This process creates compressive stress in the surface layer, significantly increasing the glass's strength.

At Dubiel Vitrum, the tempering process produces:

  • Flat toughened ESG glass
  • Bent glass with cylindrical shapes (safe ESG glass)
  • Thermally strengthened TVG glass (so-called semi-toughened)
  • Flat toughened ESG glass painted with cured ceramic paints (enamel paints applied to the entire surface or via screen printing).
TECHNICAL CONDITIONS FOR GLASS TEMPERING
Glass Thickness 4 - 19 mm
Glass Dimensions
  • Minimum: 350 x 60 mm
  • Maximum: 2440 x 4000 mm (recommended: 2440 x 3200 mm)
Types of Glass
  • Float
  • Low-iron
  • Body-tinted
  • Etched (tempered with the smooth side or etched side towards the rollers)
  • Painted with single-layer ceramic paint (tempered only with the smooth side towards the rollers)
  • Coated, suitable for tempering (hard coatings)
  • Patterned
Pre-tempering Glass Processing Limitations
  • Glass must not have sharp edges (edges and corners must be chamfered or rounded before tempering).
  • Minimum internal cutout radius:
    - R = 6.5 mm for glass thickness 3 - 6 mm
    - R = 8 mm for glass thickness 8 - 12 mm
    - R = 10 mm for glass thickness 15 - 19 mm
  • Minimum hole diameter must be equal to or greater than the glass thickness.
  • The distance between holes must be equal to or greater than twice the glass thickness (Fig. 1).
  • The distance from the edge of the hole to the glass edge must be at least twice the glass thickness (Fig. 1).
  • The distance from the edge of the hole to the sharp corner of the glass must be at least six times the glass thickness (Fig. 1).
  • The distance from the edge of the hole to the rounded corner (at an acute angle) must be at least six times the glass thickness, measured from the hole edge to the theoretical sharp corner of the glass (Fig. 1).
  • The distance between countersunk holes must be at least twice the glass thickness, measured from the edge of the countersink (Fig. 2).
  • IMPORTANT:
    If the holes do not meet the tempering standards, modifications to the design can be made:
    - Moving the holes
    - Reducing the diameter
    - Connecting the holes (e.g., slot holes)
    - Adding a bridge
Glass Tempering Diagram 1 Glass Tempering Diagram 2
Post-tempering Glass Processing Limitations
  • Tempered glass cannot undergo further hard processing (such as cutting, drilling, or edge grinding) due to the high risk of breakage or permanent weakening of the glass. However, tempered glass can be:
    • Sandblasted
    • Printed
    • Painted with water-based paint
TEMPERED GLASS MARKING
Tempered glass produced by Dubiel Vitrum is marked with a permanent CE symbol, confirming compliance with the PN-EN 12150 standard.
Tempered Glass ESG
CE Marking Size: 12 x 16 mm.
Glass Thickness: 4-19 mm
Glass Tempering
CE Marking Size: 19 x 1.6 mm.
Glass Thickness: 5-19 mm

Thermally Strengthened Glass TVG

Thermally Strengthened Glass TVG

Thermally strengthened glass, also known as semi-tempered glass, is commonly used in construction. Similar to tempered ESG glass, it offers greater mechanical and thermal resistance compared to annealed float glass, albeit with lower strength than fully tempered ESG glass. A distinguishing feature is its characteristic crack pattern upon breakage: the glass breaks into larger pieces that radiate toward the edges, preventing the pane from falling out of the frame. In contrast, tempered glass shatters into small, blunt fragments.

Thermally strengthened glass is denoted by the abbreviation TVG (from the German *Teilvorgespanntes Glas*).

Thermal strengthening is a process similar to tempering but involves a slower cooling intensity. Air cooling induces compressive stresses, enhancing the glass's strength. The internal stresses generated during this process are relatively lower than those in tempered glass.

Thermally strengthened glass ("semi-tempered") produced by Dubiel Vitrum is marked with a permanent CE symbol, confirming compliance with the PN-EN 1863 standard.

TECHNICAL CONDITIONS FOR THERMAL STRENGTHENING OF GLASS
Glass Thickness 4 - 10 mm
Glass Dimensions
  • Minimum: 350 x 60 mm
  • Maximum: 2440 x 4000 mm (recommended: 2440 x 3210 mm)
Types of Glass
  • Float
  • Low-iron
  • Body-tinted
  • Etched (tempered with the smooth side and the etched side towards the rollers)
  • Coated (tempered with the uncoated side towards the rollers)
  • Patterned
Limitations Related to Glass Processing Before and After Tempering
  • Identical to the conditions for ESG tempered glass (see section 2.1, table "Technical Conditions for Glass Tempering").

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