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Brief introduction

Insulating glass has a low heat transfer coefficient and is a kind of energy-saving glass. After more than 30 years of development, it has been widely used in construction and other fields.

Insulating glass products can only be used after passing the inspection according to industry standards. To ensure the consistency of products, its quality process control is particularly important. Only by controlling the quality of each link in the production process can we ensure that the final products meet the standard requirements.

1. Production process

The production process of rigid spacer type insulating glass is shown in Figure 1

Figure 1 The flow chart of rigid spacer type insulating glass production

Figure 1 The flow chart of rigid spacer type insulating glass production 

2. Precautions for the production of insulating glass

(1) The production site of insulating glass should be in a clean, dry, and well-ventilated room

(2) The production enterprise shall have all the production equipment that meets the production requirements;

(3) Necessary measuring tools and testing equipment shall be available;

(4) The operators engaged in the production of insulating glass should have the corresponding professional skills, and they should hold the certificate after passing the training and assessment;

(5) There should be complete system documents and effective operation, and key processes should have clear operating procedures or work instructions to ensure safe production and strictly control the production quality of insulating glass.

(6) The cutting of glass should avoid scratching the glass, and use volatile and easy-to-clean cutting oil;

(7) The processing accuracy of the glass cutting machine and the edging machine should meet the requirements of the dimensional accuracy, diagonal accuracy, and edge quality accuracy of insulating glass;

(8) The washing and drying machine should choose a brush with an appropriate hardness to avoid scratching the film layer of the coated glass, and the drying air should be filtered;

(9) Deionized water should be used for the first cleaning water of ordinary glass; deionized water should be used for cleaning coated glass; the conductivity of deionized water should be less than the 20 s/cm. Defects such as scratches, broken corners, water stains, or residual water droplets are not allowed on the cleaned glass surface;

(10) When using coated glass to make insulating glass, the edge sealing area should be removed. For insulating glass that needs to be opened, the sealing area at the opening should also be removed.

Figure 2 The glass cutting: the production processing of insulating glass 1

Figure 2 The glass cutting: the production processing of insulating glass 1

3. Quality control points of each process

3.1 Film loading, film removal, the washing process

Check whether the thickness, size, variety, film type, edge type, quantity, appearance, film surface orientation, etc. of the glass are consistent with the task, and also check the film surface defects (release film, scratches, shadows, spots, oxidation, tin melting, etc.).

The size of the film removal should be accurate, and the error range should be ±1mm. There are two ways to distinguish the outer surface of the coated glass from the glass surface. The first is the superimposition method: put the finger close to the glass, and observe the reflection of the finger on the glass at an angle of 45° between the eyes and the glass. If the image is a single real image, it is the film surface, and the double image is the glass surface.

The second is the film surface detector test: masks and gloves should be worn when the film is operating (gloves should be kept clean), and the edge of the glass should be touched as much as possible when handling the film to reduce contact with the film surface. It is strictly forbidden for the diaphragm to stay in the washing machine. The residual glue and labels on the glass must be cleaned up. The reworked glass must be cleaned of butyl glue, structural glue, and other contaminants to avoid contamination of the washing machine. When using the suction cup, the suction cup should be cleaned. Clean up to prevent suction cup marks.

Figure 3 The Low-E glass film removal: the production processing of insulating glass 2

Figure 3 The Low-E glass film removal: the production processing of insulating glass 2

3.2 Frame making, desiccant filling, and butyl rubber coating process

Select spacers of corresponding specifications and colors. The size of the frame should be accurate. Generally, there should be no more than two joints in the same frame, and it is not allowed to reduce contact with the ground, hands, and other objects on the same side frame to prevent the resulting butyl Adhesive and structural adhesive bonding performance is reduced.

The corners of the frame must not be interrupted, and repairs can be made if necessary to prevent fingerprints and prevent contamination during the process of butyl rubber. To prevent the leakage of the molecular sieve in the hollow glass cavity, when the length of one side exceeds 2m, cover the seam with butyl glue on the outside of the interface of the frame. Frames with a unilateral length less than 1.5m are not allowed to truncate the butyl rubber and must be torn off and re-produced. Reduce the contact between butyl rubber and hands or other objects, otherwise, it will affect the sealing performance and reduce the service life of the product.

The desiccant used should be effective and sufficient. The interval frame after filling the desiccant should not be used for more than 45 minutes. The coating amount of butyl rubber should meet the requirements and be continuous and uniform, especially in the initial stage of eliminating quality problems. Light check and continue for a whiletime to ensure the issue is completely resolved. Identify the type of rubber to be used. When gluing, observe the mixing situation, whether there are "bright lines".

Figure 4 The desiccant filling: the production processing of insulating glass 3

Figure 4 The desiccant filling: the production processing of insulating glass 3

3.3 Install frame process

Check whether the width of the film meets the requirements, whether the film is clean, confirm whether the size and thickness of the glass are in line with the plan; 

check whether the glass is washed and whether there is an air knife mark; 

check whether the glass has surface defects; 

Whether there is pollution, whether the connection parts are inserted tightly, whether the molecular sieve is full, whether there is leakage, whether the butyl rubber is uniform and continuous, whether the butyl rubber at the corners is interrupted, and whether there are fingerprints and sweat on the surface. 

The frame should be straight, and a ruler should be used when producing large panes of glass. Stamping the team's stamp on the finished product label ensures traceability of product quality.

Figure 5 The install frame process: the production processing of insulating glass 4

Figure 5 The install frame process: the production processing of insulating glass 4

3.4 Sealing process

The first inspection must check both sides of the insulating glass. In normal production, every 5 pieces of glass should be inspected with a strong light, and each piece of glass should be visually inspected.

In the initial stage of eliminating quality problems, it is necessary to inspect each piece of light for a period of time to ensure that the problem is completely solved, and to clarify the type and grade of glue to be used. When gluing, observe the mixing situation, whether there are quality defects such as "bright lines" and "bubbles". Note that the corners should be full to prevent empty glue, and the glue convex and glue concave should meet the quality requirements. Verify that the thickness of the hollow cavity meets the requirements. For products filled with inert gas, measure the gas content as required.

Corners should be treated with a non-stick roller. The roll angle should be rolled from the middle of the edge to the corner, and cannot be operated in the opposite direction, otherwise, it will cause the corner to lose glue. The rolling length of the corners is about 5cm on each side, and the maximum does not exceed 10cm. Clean the glass surface after gluing. Use clips or cork pads to isolate the glass. The position of the cork pad should be aligned with the force point of the shelf to prevent the glass from being deformed and bent. When producing extra-large or extra-long glass, necessary measures should be taken to prevent the glass from bouncing off.

Figure 6 The aluminum frame sealing: the production processing of insulating glass 5

Figure 6 The aluminum frame sealing: the production processing of insulating glass 5

3.5 Inflating process

When the insulating glass needs to be inflated, there are two methods of online inflation and offline inflation. Insulating glass manufacturers should use intelligently controlled inflation equipment and conduct regular maintenance. The inert gas pressure reducing valve shall be qualified by metrological verification and shall be used within the validity period. Insulating glass manufacturers should use portable and simple inert gas concentration detectors that have passed the comparison of authoritative departments to detect gas concentration and conduct regular maintenance. When inflating off-line, the insulating glass should be placed vertically, an air suction nozzle should be reserved at the top of the length direction of the insulating glass and an inflation nozzle should be reserved at the bottom. Correctly connect the air source to the intelligent inflatable device before inflation, check the status of the smart inflatable device, and ensure that it can work normally. After inflation, seal the reserved inflation port and exhaust port with butyl rubber as soon as possible and apply two coats in time.

Figure 7 The argon-gas filling: the production processing of insulating glass 6

Figure 7 The argon-gas filling: the production processing of insulating glass 6

3.6 Unloading and curing process

The insulating glass should be placed on the A-frame or L-frame, and the backrest of the shelf should be placed at an angle of 90° to the bottom edge to prevent the dislocation of the insulating glass before curing. After the component glue is more than 8h, it can be packaged.

Figure 8 The L-frame loading: the production processing of insulating glass 7

Figure 8 The L-frame loading: the production processing of insulating glass 7

3.7 Inspection process

Inspection is divided into semi-finished product inspection and final product inspection in the intermediate process. The semi-finished product inspection is carried out in each process, and the generated semi-finished product is inspected by the current process, and the next process is reviewed; the final product inspection is carried out by the quality inspector from the finished product warehouse according to the requirements of the industry standard. For the inspection of dimensional deviation, dew point, initial gas content, and other items, if necessary, a third-party authoritative organization can be entrusted to inspect ultraviolet radiation resistance, moisture sealing durability, gas sealing durability, and U value.

4. Material requirements for insulating glass

The quality of the materials used to make insulating glass should meet the requirements of the corresponding national standards or industry standards. Insulating glass can be made of flat glass, fireproof glass, tempered glass, laminated glass, coated glass, glazed tempered glass, glazed semi-tempered glass, wired glass, colored glass, etc.

The first sealant for insulating glass should use a large amount of butyl hot-melt sealant. The second sealant can use silicone glue, polysulfide glue, or polyurethane glue. The first layer of sealant and the second layer of sealant should be tested for compatibility. The first layer of sealant, the second layer of sealant, and the spacer should be tested for adhesion and compatibility. The spacer should meet the industry requirements according to different types of standard requirements. The size of the connector should match the size of the inner hole of the spacer, the dimensional tolerance should meet the requirements, and the surface should be clean. Angle inserts and straight inserts should be designed with stop teeth to prevent the spacer from loosening.

Desiccant products for insulating glass should be selected to meet industry standards.

Figure 8 The automatic production processing of insulating glass

Figure 8 The automatic production processing of insulating glass 

5. Conclusion

Insulating glass is a glass product made of two or more pieces of glass, which are evenly spaced for effective support and are bonded and sealed at the periphery so that a dry gas space is formed between the glass layers. Glass, spacers, desiccant, the first sealant, and the second sealant together form the edge sealing system of the insulating glass. 

The failure of the edge sealing system means that the insulating glass fails, and the gas in the insulating glass cavity is no longer available. is a dry gas, thereby losing energy-saving properties. The purchase of raw materials that meet the standard requirements and the quality control of all key processes of insulating glass is to ensure that the edge sealing system is more reliable and the energy-saving effect of insulating glass.


 For more information about Jinan LIJIANG Glass insulating glass processing equipment and insulating glass processing accessories, please click here to learn more. 

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