"Siliconized" Machine Windows

T2K has been informed by a number of customers that scratch resistant "siliconized" machine window are offered as a replacement option for machine windows surfaces which become badly damaged due to chip activity. Bonding Visiport or DiscAir spin window systems to such siliconized polycarbonate is not recommended for several reasons.

1) Material Compatability Issues
The 3M VHB+ material used on all mounting systems for Visiport and DiscAir products is based on an acrylic carrier closed-cell foam. A window material with a silicone-based coating is fundamentally compatible only with other silicone products. While the edge sealing material T2K supplied is compatible, the VHB+ material, being acrylic based, is not. As such, bonding is somewhat compromised in theory.

Based on our testing, however, any T2K spin window bonded according to the instructions laid out in the Installation documents will bond adequately well, as the area required for bonding is many times greater than that required to hold the unit onto the substrate. (Keep in mind that the secondary purpose of the bondset is as a gasket.) The installation instructions are available for download from each Visiport product page and supplied with the product.

2) Poor Cost-Benefit Ratio
As we hear it from the customers actually buying these products, the cost factor is much higher than for the simple, plain optical grade polycarbonate commonly used in the industry. If, however, the point is to increase the life of the window in a machine tool application, then this money is by and large wasted as the extra life provided by the siliconized surface is only marginally longer than for polycarbonate without it.

Truly, if you have a machining application that has sufficient chip activity that the ability to look through the polycarbonate window is destroyed, then you would be far better served either installing a Visiport and allowing the rest of the polycarbonate window's view area to degrade as before, or replacing the polycarbonate window with a safety window incorporating a glass surface on the inside of the machine to resist the chip activity of your application. The use of either window type, of course, does not impact your ability to bond the Visiport on, although a better bond is achieved in practice with glass due to the difference in surface energy this material provides.

3) Downtime and Availability
When the time comes to replace the window, either due to chip activity affecting visibility, metalworking fluid replacement guidelines (which at two years is no different than standard polycarbonate), cracking, or damage due to tool impact, a siliconized window may or may not be available from your OEM as quickly as standard polycarbonate. Certainly it will be more expensive.

T2K can provide you with either a new mounting plate or offer our factory rebonding service to replace the bondset from directly mounted spin windows. With our factory pre-mount service, we can send your Visiport clean, refurbished, and mounted so that you can minimize the downtime switching the old window for new.

For additional information, contact T2K.