The basic limit of the original film size
All deep-processed glass begins with float glass sheets. The common original film size specifications in China are:
Conventional large plates: 3300mm x 2140mm (commonly known as "three meters three"), 2440mm x 1830mm, 2134mm x 1830mm, etc.
Imported or special original pieces: There may be larger sizes such as 6000mm x 3210mm, but they are less common.
Core principle: The final size of any deep-processed glass must be able to be cut from these standard-sized original sheets, and cutting losses and grinding allowances must be taken into account.
Ii. Size restrictions for major deep processing categories
Different processing techniques have different requirements for equipment, and thus the size restrictions also vary.
1. Tempered glass
This is one of the processes with the strictest size restrictions, as the tempering furnace has a fixed furnace chamber size.
Minimum size: Generally, the single-sided length is required to be no less than 300mm. Glass that is too small is prone to flipping and colliding in a tempering furnace, leading to breakage or quality defects.
Maximum size: Determined by the specifications of the tempering furnace. The processing upper limit of the common horizontal tempering furnace is approximately:
Conventional furnace: 3300mm x 2140mm (matching the mainstream original sheet size)
Extra-large furnaces: 4500mm x 2140mm, 6000mm x 2440mm or even larger (special customization required, high cost).
Thickness range: Usually 4mm-25mm. Glass of different thicknesses has different requirements for furnace temperature and air pressure, and the capacity of the equipment also determines the thickness range it can handle.
Tempered glass has "bow-shaped deformation" and "wave-shaped deformation". The larger the size and the thinner the thickness, the more difficult it is to control the deformation. Therefore, large-sized thin glass has extremely high requirements for equipment and processes.
The size limitations mainly come from the dimensions of the autoclave or vacuum system, as well as the pretreatment equipment before lamination (such as cleaning machines, tempering furnaces).
Maximum size: It is usually consistent with the maximum size of the original glass sheet used (especially tempered glass), as the substrate size of laminated glass cannot exceed the capacity of the tempering furnace. The size of an autoclave is generally designed to be slightly larger than that of a tempering furnace.
Minimum size: There are no particularly strict restrictions, but if it is too small, it will affect production efficiency.
Thickness limit: Theoretically, there is no upper limit, but overly thick glass (such as bulletproof glass) requires a special large autoclave.
The size limitations mainly come from hollow lines (including cleaning machines, laminating tables, gluing machines, etc.).
Maximum size: Determined by the conveying, laminating and gluing capabilities of the hollow line. The maximum processing size of common hollow lines is approximately 4000mm x 2500mm. Greater needs for customized equipment.
Minimum size: Generally, there is no strict lower limit, but it is not economical if it is too small.
Aspect ratio: To ensure the sealing performance and structural stability of the insulating layer, it is generally recommended that the aspect ratio of a single piece of glass does not exceed 3:1, and overly slender shapes should be avoided.
4. Coated glass (offline)
The size limitations mainly come from the vacuum chamber dimensions of large magnetron sputtering coating machines.
Maximum size: This is a very crucial parameter. Common specifications of coating machines include 2400mm x 3600mm, 3300mm x 5100mm, etc. The size of the glass you need must be large enough to fit into the cavity of the coating machine.
Minimum size: Similarly, for production efficiency, there is usually a minimum order size requirement.
Iii. Tolerance Standards
The processing dimensions not only have maximum and minimum values, but also precision requirements, that is, tolerances. This is an important indicator for measuring the processing level.
Cutting size tolerance: usually ±1.0mm to ±2.0mm.
Diagonal deviation: For rectangular glass, the difference in length between the two diagonals. General requirements
When the size is ≤ 2000mm, the deviation is ≤ 2.0mm.
When the size is greater than 2000mm, the deviation is no more than 3.0mm.
The hole diameter and hole position tolerance of tempered glass: There are strict national standards (such as GB 15763.2-2005), and the hole position tolerance is usually between ±0.5mm and ±1.0mm, with the hole diameter tolerance being ±0.5mm.
Iv. Considerations for Design and Transportation
Structural limitations of buildings: The size of the installation openings for glass curtain walls or doors and Windows determines the final size of the glass. The tolerances of the building and the reserved gaps for thermal expansion and contraction must be taken into consideration.
Transportation restrictions
The inner dimensions of a standard container are approximately 2350mm (width) x 2390mm (height). This means that any glass over 2.4 meters on either side needs to be placed in a special way or transported using open-top boxes or frame boxes, resulting in a sharp increase in costs.
Road transportation: The width and height of the truck's cargo box are also limiting factors. Extra-wide and extra-high glass requires special transportation procedures.
Summary and Suggestions
To determine the processing size standards for your deep-processed glass, please follow the steps below
Clarify the final use: Is it for building curtain walls, doors and Windows, interior partitions, or furniture and household appliances? This determines its performance requirements and the allowable tolerances.
Confirm the availability of the original sheet: Can the size you designed be efficiently cut from standard boards such as 3300x2140 to avoid excessive waste?
Consulting the processing factory: This is the most crucial step. Before the final drawing is confirmed, you must provide your size requirements (especially for oversized, extra-thick, irregular-shaped or perforated glass) to the intended deep processing manufacturer. They will inform you based on the specific capabilities of their equipment
Can it be processed?
Is there a risk of deformation?
The corresponding price and delivery time.
In conclusion, there is no one-size-fits-all size standard for deep-processed glass. It is a comprehensive and dynamic standard system based on "raw sheet - equipment - application - transportation". Maintaining close communication with your processing service provider at all times is the core to ensuring the smooth progress of the project.
