Perforation is to punch a series of small holes in a substrate such as metal sheet,plastic sheet,leather or paper.There is usually more than one perforation in an organized fashion, where all of the holes are called a perforation. The process of creating perforations is called perforating.
Nowadays,CNC perforating machine are widely used for perforation.Die and punch sets can be used for perforating.The process is the most common for metalworking and plasticworking.The workpiece is sheared by pressing of the punching machine,the punch through the workpiece and into the die. The middle section of the workpiece is scrap.The punch and die are shaped to produce the desired shaped hole.The clearance (the distance between the outside circumference of the punch and the inner circumference of the die) must be properly maintained to ensure a clean cut. Burrs are produced on the side of the workpiece that is against the die.
There are some terms for perforation as follows:
1.Material Thickness: The thickness of plastic sheet will affect the hole diameter and pitch,normally,the hole size shoud not be smaller than the thickness of the plastic sheet,the same as metal sheet.
2.Hole shape and pattern:Round holes are the most popular,which covers straight hole pattern and staggered pitch hole pattern such as 60 degree,45 degree staggered round hole pattern.
3.Hole diameter:As mentioned above,the hole diameter can be affected by the thickness of the plastic sheet and metal sheet.The thickness of the sheet and the hole size should not go below 1-to-1 ratio.Stay at 2-to-1 or larger if possible.
4.Center distance:It controls feed rate and thereby the production rate.If possible, choose a pattern with longer center distance.The thicker the plastic sheet is,the longer the center distance should be.
5.Open areas: It is decided by the hole size and center distance.
6.Margins:Margins mean the hole-free area,normally,we will keep side margins to a minimun to reduce distortion. Use standard Unfinished End Margins if you can.See Unfinished End Margins vs. Finished End Margins here.
Micro Perforation isn't defined in the dictionaries I have. "Micro" however,is defined as "very small" which leaves us with a definition of micro perforation as a "series of very small holes in a substrate." How's that for a very subjective and relative term?! In the packaging industry, which deals extensively with a nearly infinite variety of perforating rules, a micro perforation has come to be known as a perforation in the 15 to 20 teeth-per-inch range, or higher.