IGUs’ are basically multiple layered glass panes that have

very dry air or inert gas between the glass panes. The glass panes

are hermetically sealed. 

Surface #1 is facing outside

Surface #2 is the inside surface of the exterior pane

Surface #3 is the outside surface of the interior pane

Surface #4 is the inside surface of interior pane The window frame is labeled #5

A spacer is indicated as #6

Seals are shown in red (#7)

The internal reveal is on the right hand side (#8)

The exterior windowsill on the left (#9)

Spacer: Spacer performs the role of keeping the glass panes apart as well acts as a housing for the desiccant.

Desiccant: Or, the drying agent performs the most important role in an IGU; that of absorbing the moisture from the hermetically sealed space.

Secondary Sealant: This sealant is applied on the outside of the unit. It performs several roles, chief among them of providing structural strength.

Primary sealant: First line of defense for the hermetic seal.

Key quality areas

There are a few key areas that are of immense importance to ensure the quality of IGU’s to ensure that clients get the performance they pay for.

Appropriate Type & Quantity of desiccant : Desiccants perform the most important role of absorbing moisture and keeping the air inside the IGU’s dry. The glass processor must use the correct type and quantity of drying agent inside the IGU. Not using the correct quantity or type of desiccant is one of the ways for a glass processor to significantly cut costs by cutting corners.

Automatic Vs. Manual Desiccant filling: The main issue is that the drying agent should never make contact with ambient air during the process of filling the desiccant inside the spacers. As soon as the desiccant makes contact with air, it starts absorbing moisture reducing life cycle performance.

Auto Desiccant Station

Desiccant is filled & sealed automatically without contact with ambient air

Number of joints in the Spacers: Ideally the spacer should have no joints. Joint-less spacers are structurally stronger. However, cost & performance tradeoffs require that an automatically bent spacer system in a single piece assembly with one side joint be used. Many processors use 4 corner joints for the spacers. This reduces the structural shear strength of IGU’s. Spacer Bending Station :- Automatic Spacer Bending creates spacers in a single piece assembly with one side-joint

Enclosed Environment: In India, IGU's should be made in an enclosed & conditioned environment; ideally at a relative humidity of less than 62% and an ambient temperature of less than 24 C. This prevents excess moisture being absorbed by the IGU's during production, as well as prevents dust from entering the units.

Secondary Sealant quantity: The secondary sealant along with the spacer provides the unit with rigidity. The gap between the spacer and the edge of the glass pane that controls the amount of secondary sealant to be filled should be appropriate for the size of the insulated glass unit.

Equipment: IGUs should be made using the proper IGU manufacturing line. A manually made IGU by sticking 2-panes together will not perform over the lifecycle of glazing. Standards: Due to the absence of any standards in India, it is highly recommended that IGU’s should be made to an international standard keeping several quality areas, including the ones above, in mind. Some applicable standards for IGUs are:

a. EN 1279-2 b. BS 5713c. ASTM E 546-88

First and foremost the right glass combination is selected according the clients requirement. The choices are limitless, for e.g. the glasses can be monolithic, annealed, tempered, Laminated, Tinted and/or reflective.

Step 1.

All spacer bars are cut to size, and are then filled with a desiccant for moisture absorption. The spacer bar is an aluminum bar that comes in various widths to customize the amount of airspace, which is required within the unit. The spacer bar sizes are as followed:

5.5mm / 7.5mm / 9.5mm / 11.5mm / 13.5mm / 14.5mm / 15.5mm / 17.5mm19.5mm / 23.5mm.

Step 2.

The spacer bars are filled with a high quality desiccant, and then assembled and prepared for the primary seal. This system ensures that the desiccant does not come into the contact of air and hence its moisture absorbing capability is intact till it goes inside the insulating glass unit.

Step 3.

Then, P.I.B(poly isobutyl) is applied to the spacer bar as the primary seal. The primary seal acts as the first seal that keeps the spacer bar at place and sticks both the panes of glass together separated by a uniform distance.

Step 4Glass is then put through the washer and arrives on to the quality control check point.

PRODUCTION PROCESS

Step 5

Quality control must then inspect to ensure the glass is clean and flawless. After the inspection has been done, the pre-prepared spacer bar is then applied. The glass with the spacer bar attached is then sent to the holding point.

Step 6.

The second piece of glass is then also put through the washer and inspected all the same, and then let through to the holding point, in which case the machine automatically aligns the two sheets of glass

Step 7.

The two sheets are then pressed in the large glass press, and the automatically released out the other end. Then the Insulated Glass Unit is transported using the glass lift and is then ready for the application of the secondary seal.

Step 8.

The secondary seal is applied all around the unit, in either butyl or silicon depending on the size and what the purpose of the unit is.

Step 9.Once the secondary seal process is complete, the unit is left to dry, which brings us to the end of the manufacturing process.

Properties of Insulated GlassDescription Double or Triple pane Insulated glass units separated by

aluminum spacers

Spacer Thickness 6, 8, 10, 12, 15, 18, 24mm available in stock Thicker spacers made on special order

Spacer Bending Full automatic Single piece assembly with one side joint Corner key assembly available (not recommended)

Desiccant Filling Full automatic No contact of desiccant with ambient air

Desiccants type Molecular sieve IV

Environment Enclosed air-conditioned £ 24 ° C temperature £ 62% Relative humidity

Secondary sealants(performance parameters)

Polyurethane, Poly sulphide, and/or Silicone based from reputed manufacturers. In service temperature range -30 ° C to 80 ° C Short exposure (up to 1 hour) 100 ° C to160 ° C

Space between glass edge & spacer

Please see Next Slide

Configuration Joint depth Beneath depth

2x 4mm glass (short side)•  > 500mm•  <500mm

 5mm5mm

 

3mm 3mm

2x 5mm glass (short side) •  > 500mm •  <500mm

5mm 5mm

3mm 3mm

2x 6mm glass (short side) •  > 500mm •  <500mm

5mm 6mm

3mm 4mm

2x 8mm glass (short side) •  > 500mm •  <500mm

6mm 8mm

4mm 6mm

Arched units 2x 4mm 6mm 4mm

Arched Units > 2x 4mm thick

8mm 6mm

Shapes Stepped glazing Any shape for which a drawing can be made, E.g. Oval, arches, triangular, hexagonal, etc. (min size limitations for bending apply)

Edge processing Rough Grinding; CNC ground arise for tempered IGU Belt grinding for annealedEdge Deletion for Low-e coating

Rectangular Dimensions (Maximum)

3050mm x 1830mm Tolerance ± 2%

Rectangular Dimensions (Minimum)

280 x 280mm (rectangular) 450mm x 480mm (shaped glass, depending on shape)

Thickness 74mm max. Tolerance ± 1mm

Angularity Maximum diagonal difference of £ 4 mmEvenness/war page < 1% for annealed glass 

< 2% for tempered or heat strengthened glass

International Standards (Meet or exceed)

EN 1279-2:2002