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Safety Window Construction

Current construction for machine tool safety windows is generally of three basic types: monolithic polycarbonate panels, air gap windows, and laminated composite windows.

Polycarbonate Panel Benefits

ALL machine tool safety windows use polycarbonate (PC) to do the work of protecting operators from impact injury. Relatively inexpensive and optically clear, polycarbonate is an incredible material, providing 250 times the impact resistance of a comparable thickness of glass.

By itself, a polycarbonate panel of the appropriate thickness can provide the necessary impact resistance to protect the operator from injury, assuming the enclosure is also properly designed to retain the impact energy.

Polycarbonate Panel Drawbacks

While polycarbonate panels can affordably provide impact resistance, the longevity of the protection is affected by chip activity and the exposure of the material to metalworking fluids. Over time, chip activity abrades the surface of the material, damaging its optical clarity. Visibility is further obscured by metalworking fluid contamination on the scratched surface.

Aside from loss of visibility, more worrying is the tendency of polycarbonate to lose its impact resistance over time due to exposure to metalworking fluids. In long-terms tests done in Germany, impact testing of polycarbonate found that in some cases the panel failed under impacts that were 10-15% of the original resistance level of the material. Moreover, it was not possible to visually determine which panels had been weakened and which had not. As a result, the German machine tool builder's association, the VDW, long ago classified unprotected polycarbonate as wear item that ought to be replaced every two years for operator safety.


To overcome these drawbacks and preserve the service life of the polycarbonate panel, encapsulation of the panel to prevent any exposure to metalworking fluids and chips is common. Both air gap windows and laminated composite windows approach encapsulation of the polycarbonate in a similar manner.

The exterior layer, exposed to airborne metalworking fluid mists outside of the machine, is either hard coated or combined with an outer plastic layer like polyethylene terephthalate (PET). The interior layer is protected from chips and metalworking fluids with a layer of tempered glass. The edges are covered with a rubberized material, or frequently with urethane if the panel layers are bonded into a metal frame.

Air Gap & Laminated Safety Windows

The difference between the two type of composite construction safety windows is in the method employed to bond them together. Air Gap Safety Windows use an adhesive tape material to bond the glass and polycarbonate panels together around the perimeter of the window, which leaves a gap between the layers. This air gap is thought to be potentially useful in the spreading of impact energy across the panel surface. Laminated Safety Windows, on the other hand, use an interlayer of urethane adhesive to bond the materials together.

Custom Safety Windows

Regardless of the type of safety window you need: composite safety windows with air gap or laminated construction, or a simple monolithic polycarbonate panel, Visiport can provide you with new or replacement safety windows quickly and affordably. Working directly with the manufacturer, we can offer reasonable pricing and a fast delivery of your custom window. No matter the frame configuration, mounting feature, or impact class required, Visiport offers the widest selection of safety window replacements for your machine tool needs.


The fastest way to get a quotation for your particular machine tool safety window requirement is to download our Quotation Intake Form.

If you need have any questions about safety windows or hwo to get a quotation, please contact us for assistance.