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For a glass fabricator, nothing destroys profit margins faster than a scratch on a finished Low-E coated unit or a custom tempered sheet. It’s not just about the cost of the cullet; it’s the production delay and the reputation hit with your glazing contractor. If you are seeing hairline scratches or edge chips during internal WIP flow or truck delivery, your racking system is likely the culprit. Here is the engineering logic behind surface protection. |
In many generic glass transport racks, the rubber padding is simply glued onto the steel frame. In a hot warehouse or under the intense UV exposure of a jobsite delivery, that glue degrades. When you load 3,000 lbs of architectural glass onto the rack, the shear force peels the rubber away.
Once that rubber shifts, your glass edge makes direct contact with the steel upright or the base. This "hard contact" is the primary cause of shell chips and deep scratches.
The Fix: We utilize a Steel-Core Rubber Profile (EPDM). This isn't just a strip of rubber; it has a steel plate vulcanized inside it. We secure it to the rack using self-tapping screws that go through the inner steel core. It provides a mechanical lock that will never peel, slide, or detach, regardless of heat or load weight.
Steel-core rubber profiles secured mechanically to prevent detachment under heavy glass loads.
Scratches often occur between the glass sheets (rub marks) during transport. This happens when the rack itself flexes. If your L-Shape Glass Holding Rack is built with thin-wall tubing (under 2.0mm) or uses spot welding, the entire frame will twist when the delivery truck hits a bump.
This twisting motion transfers kinetic energy to the glass pack, causing the sheets to grind against each other or against the separating cork pads.
The Engineering Solution: We use Q235 Carbon Structural Steel with a wall thickness of 2.5mm to 3.0mm for main load-bearing posts. Combined with a Full Seam Welding process (no spot welds), this creates a rigid chassis that absorbs road vibration rather than transferring it to the glass. A rigid rack means a static glass pack, which means zero scratches upon arrival at the customer's shop.
Sometimes the scratch comes from the bottom up. In a busy glass fabrication plant, glass chips and metal filings accumulate on the floor. If your rack's base rubber is soft or textured in a way that traps debris, a tiny shard of glass embedded in the rubber becomes a diamond cutter against the bottom edge of your Insulated Glass Unit (IGU).
We use a specifically formulated hardness (Shore A 70-80) for our base rubber. It is hard enough to resist debris embedding but soft enough to cushion the glass. Furthermore, the L-shape design allows for easy visual inspection and cleaning of the base before loading, unlike complex A-frame structures where debris hides in the crevices.
Correct vertical storage with debris-resistant rubber prevents edge chipping and bottom scratches.
Improper lean angles are a silent killer of surface quality. If a rack is perfectly vertical (90°), the glass is unstable and requires excessive strapping force to hold it back, which can crush the outer lite. If the angle is too steep (like some timber A-frames), the sheer weight of the stack puts immense pressure on the rear sheets, often imprinting the separator pads permanently onto soft-coat Low-E surfaces.
Our racks feature a scientifically calculated 3-5 degree tilt. This allows gravity to gently hold the glass against the structural back uprights without creating excessive pressure points that damage coatings or cause lamination separation.
1. Can your racks handle "Jumbo" size glass sheets without bowing?
Yes. For Jumbo sheets (over 130 inches), we use reinforced 60x60mm posts and increase the wall thickness. The rigidity prevents the center of the glass sheet from bowing and touching the metal structure.
2. How often should we replace the rubber on the racks?
With our steel-core EPDM profile, replacement is rarely needed due to wear. However, we recommend a visual inspection every 6 months to ensure no foreign materials (metal shavings, glass chips) are embedded in the surface.
3. Is powder coating better than painted steel for preventing rust stains on glass?
Absolutely. Wet paint often chips, exposing raw steel that rusts. Rust water dripping onto glass requires expensive acid washing to remove. Our electrostatic powder coating (RAL 5010) is baked on, creating a sealed barrier that prevents rust contamination.
4. We transport soft-coat Low-E glass. Do you have specific recommendations?
For soft-coat, the rack stiffness is critical to prevent micro-movements. We also recommend using cork distance pads with a non-adhesive backing alongside our rigid L-racks to ensure the coating never touches another surface.
5. Do these racks work for both factory WIP and truck delivery?
Yes. The "Grack" is designed as a hybrid. It has forklift channels for factory movement and crane lifting eyes for site unloading. This reduces the number of times you have to handle the glass (re-racking), which is when 90% of scratches occur.
