perforations

Perforation refers to a hole that passes completely through a material or tissue, creating an opening from one surface to the opposite side. Perforations can be intentional, as engineered features in sheets and membranes, or pathological, arising from disease, injury, or medical procedures. The term is used across disciplines, including materials science, printing, biology, and medicine.

In materials engineering, perforated sheets contain regularly spaced holes. Key parameters include hole diameter, pitch (center-to-center distance), pattern, and open-area ratio. Perforations affect strength, weight, permeability, and acoustic or thermal behavior. Common fabrication methods are punching, laser drilling, mechanical drilling, and chemical etching. Applications range from filtration and screens to acoustics, architectural facades, catalyst supports, and venting in packaging.

Medical and biological perforations denote full-thickness openings in hollow organs or tissues. Common sites include the gastrointestinal tract, such as the stomach or intestines; perforations may result from ulcers, diverticulitis, inflammation, trauma, ischemia, or invasive procedures. Symptoms often include sudden, severe abdominal pain and signs of peritonitis; diagnosis relies on clinical assessment and imaging. Treatment is typically urgent surgical repair or resection, plus antibiotics and supportive care. Iatrogenic perforations can occur during endoscopy or other procedures.

In printing, stamping, and packaging, perforations are deliberate tear lines that divide a sheet into smaller sections for easy removal or separation, as seen in stamps, tickets, or coupons. They are produced by dies, scoring, or perforation blades.