Why do you “precision mill” solid vinyl ESD tiles?
Understanding what solid vinyl tile (SVT) is and how it is made will help you understand the advantages of precision milling.
SVT has the same color pattern and material composition on both sides of the tile. This is because the color pattern goes through the whole tile to the back. Solid vinyl tiles are just what the term implies, vinyl without any fillers. ESD solid vinyl tile also has the same conductive elements through the full thickness of the tile. You can read more about SVT here at this link
How solid vinyl tile is made?
Step One: Hot Press
Solid vinyl tile is made in large batches starting with a process known as hot pressing. Large pans 37 inches by 37 inches by approximately 2 inches deep are filled with a combination of plastic resins, conductive plastocol and pigments. Under heat and pressure the resins and pigments mix with the conductive materials. The result is what we call a rough slab.
Step 2: Skiving
The slabs are automatically removed from the pans and placed between a series of pinch rollers. The rollers transport the warm slabs through a horizontal cutter called a skiving machine. The skiving machine cuts the slab’s thickness in half, yielding 2 rough slabs - one half the thickness of the original slab. This process is repeated until we have eight 37-inch square slabs approximately 5/32” thick.
The 5/32” slabs move from the skiving operation on to a conveyor. The tiles are rough sanded on one side. The sanded side will become the bottom of the tile. The sanding allows the tile to hold adhesive and provide a good bond during installation.
After sanding the rough slabs move through a wet polishing operation. This operation seals the top surface of the tile. Polishing produces a factory finish on the tile. This finish can be further enhanced after installation using nothing more than a low speed buffer with a polishing pad.
The 37” by 37” slabs are die cut in-line using a long centre bevel die. These types of dies cut the tile edges on a slight angle. Cutting on an angle eliminates material deformation during the cutting process. However, angle cutting leaves the tile with a reverse bevel that needs to be removed. High quality ESD vinyl tiles should be cut approximately 1/32” larger than their final dimension.
Precision milling is the most critical step in the manufacturing of perfectly square solid vinyl tiles. European and North American SVT manufacturers use this process. In this process we create a perfect 90-degree angle by removing approximately 1/32” of material along both edges. Most imported tiles are not precision milled due to the added time and expense.
Precision Milling accomplishes 3 goals:
- Milling removes the weak point on the tile edges – the beveled edge from die cutting and the void created by the reverse bevel when 2 tiles are placed next to each other. Precision milling or micro-polishing, removes angles, enabling adjacent tiles to fit flush against one another.
- Eliminates Shingling and Creeping: Since any sub floor will have slight deviations in flatness, a reverse bevel allows lower tiles to climb over higher adjacent tiles. This is called the “shingle effect.” Shingling causes lines of tile with the installation to go out of square. Periodic cutting of rows of tiles is the only way to regain a straight line. . The best way to prevent shingling and resultant seam gaps is to produce tiles with pure 90-degree cuts.
- It polishes the edges of the tile. Edge polishing eliminates the unevenness and micro fractures created by die cutting - enabling a tighter fit between tiles.
- It precision sizes the tiles after resin curing and chemical cross-linking have reached completion. Solid vinyl tile cures for several hours after it has been produced. The best assurance against size deviation is to wait at least 24 hours before final sizing of the tile.
Ask your installer:
Most experienced installers can identify a precision milled floor tile after installing just a few rows of tiles. A precision milled tile installs tight without gaps, shingling or row creeping, enabling a faster cleaner installation. A gap free installation stays clean for the life of the floor because there is now where for dirt to collect in the first place.