Monday, May 3, 2021

Face shield

Face shield     

A face shield, an item of personal protective equipment (PPE), aims to protect the wearer's entire face (or part of it) from hazards such as flying objects and road debris, chemical splashes in laboratories or in industry, or potentially infectious materials in medical and laboratory environments.

A face shield is intended to protect the wearer's partial or entire face and the eyes from hazards. Face shields should be used with spectacles and/or goggles.

Polycarbonate (PC)

Provides excellent impact resistance, optical quality, heat resistance and normal chemical resistance.

Cellulose acetate (CA)

Provides normal impact resistance, optical quality, heat resistance and good chemical resistance.

Two methods are used to manufacture face shields:

 extrusion and injection molding. Faceshields cut from extrusion sheets provide better impact resistance than injection molded faceshields because extrusion sheets are made of high molecular weight plastic pellets while injection molding must use lower molecular weight plastic pellets, which provide better melt flowing property needed by injection molding. For example, even faceshields 0.8 mm thick made of extrusion polycarbonate sheets can withstand the impact of a 6 mm nominal diameter steel ball traveling at the speed 120 m/s (European standard, protection against high-speed particles – medium energy impact), while injection molding faceshields must have at least 1.5 mm thickness to withstand the same impact. But injection molding can provide more complicated shape than extrusion.

No comments:

Post a Comment