What is Simultaneous Cutting? - Kevin Carey

[Chris]

What is Simultaneous Cutting?
By : Kevin Carey

Simul­ta­ne­ous Diecut­ting is a some­what illog­i­cal means of ‘die-cutting.’ For exam­ple, to cut a thin sheet of paper­board, rub­ber, or plas­tic the mate­r­ial is posi­tioned upon an anvil or a flat plate and a razor blade would be a log­i­cal choice as an effi­cient cut­ting imple­ment. How­ever, instead of angling the blade to pen­e­trate and then draw­ing it through the mate­r­ial as one would expect, see left, the entire knife edge of the blade is posi­tioned against the sur­face of the mate­r­ial, see right, and then the upper edge of the blade fer­ule is struck with a ham­mer to drive it into and com­pletely through the mate­r­ial! See below.

This is hardly the image the aver­age per­son would visu­al­ize if you described an effi­cient method of cut­ting a mate­r­ial! This type of cut­ting pro­ce­dure is called a simul­ta­ne­ous cut­ting process because the entire cut­ting action takes place all at the same time. In other words every part of every cut­ting edge will strike to mate­r­ial at the same time and the mate­r­ial will be cut apart in a sin­gle pinch­ing, burst­ing action. Clearly there are some tech­ni­cal dis­ad­van­tages with this approach when com­pared to the incre­men­tal cut­ting process.

In incre­men­tal cut­ting only a small amount of the blade is used at any given time, how­ever, in simul­ta­ne­ous cut­ting the entire length of the blade is used in a sin­gle impres­sion. See right. This also clearly means the amount of pres­sure applied at any one time is much greater in the simul­ta­ne­ous process than the incre­men­tal process. See left.

In addi­tion, as the entire cut­ting action of the simul­ta­ne­ous process is instan­ta­neous any vari­a­tion in caliper, den­sity, hard­ness or fiber mix in a mate­r­ial will impair the cut­ting action. This is because when using the incre­men­tal slic­ing action, pres­sure is con­cen­trated on a small point of the knife edge and a minute area of a mate­r­ial at any given moment, there­fore, the impact these vari­ables have on cut­ting effi­ciency is min­i­mal. How­ever, as simul­ta­ne­ous cut­ting hap­pens all at the same time it is dif­fi­cult to vary pres­sure selec­tively on dif­fer­ent areas of the blade to com­pen­sate for mate­r­ial vari­a­tion. See right.

Com­pound­ing the prob­lem of simul­ta­ne­ous cut­ting is the plate or anvil the mate­r­ial is trapped against. See left. Obvi­ously a hard mate­r­ial such as steel must be used so the repeated impres­sions of the razor blade do not wear a groove in the sur­face of the cut­ting plate, as when cut­ting onto a sac­ri­fi­cial cut­ting anvil/plastic com­pound which is designed to be dam­aged. See below.

How­ever, if the blade strikes the plate with exces­sive force, see below left, because too much pres­sure was used or the mate­r­ial being diecut was softer than expected, the knife cut­ting edge or tip would be com­pressed, swaged and dam­aged. See below right.

There­fore, a great ques­tion to ask is … If Incre­men­tal Cut­ting is much more effi­cient than Simul­ta­ne­ous Cut­ting why is Platen Diecut­ting the dom­i­nant vol­ume man­u­fac­tur­ing tech­nol­ogy? To under­stand how the appli­ca­tion of these dif­fer­ent meth­ods of cut­ting is applied to pro­duc­tion diecut­ting it is use­ful to exam­ine the alter­na­tive diecut­ting tech­nolo­gies and deter­mine how the prin­ci­ples and prac­tices of each sys­tem of diecut­ting can in fact, com­pli­ment each other.

A com­pre­hen­sive under­stand­ing of how Simul­ta­ne­ous Pro­cess­ing works and Incre­men­tal Pro­cess­ing works, and to have the abil­ity to inte­grate each into the other process is an essen­tial skill in achiev­ing pro­duc­tive suc­cess in diecutting.