There are three different styles of matrix to choose from, each with its own benefits, whether it be material, shape, or price.

Shreiner Profile

Shreiner Profile matrix is a style that has gained tremendous popularity among die-cutters over the years.  Profile is a plastic matrix with a mylar base, and is the only matrix with a unique beveled shoulder that rolls from one side of the cutting plate to the other, which helps the material to glide over the plate after it has been die cut.  There are a multitude of size options to meet the needs of commercial printers, folding carton plants, and corrugated die cutters. Profile is extremely durable, has tight tolerances, and is cost effective.  This is our premier matrix product, and we recommend it to everyone.  It works well for any length run, any style press, and the price makes it affordable to both small and large die cutters alike.  As an added bonus, we have the ability to off center any size of Profile, and we are the only company in the US that can offer this value added service.

Shreiner Metal

Shreiner Metal is the original, most economical,  and at one time was the most widely used style of matrix.  Shreiner Metal is an excellent option for short runs on cylinder and clamshell type presses using virgin material.  Metal is a good choice for printers that are running a couple thousand impressions on cover stocks, or have older dies with score rule already set up to accommodate this style of matrix.

Pink

Pink matrix is the replacement for the popular, but discontinued, fiberboard style of matrix.  The make up of Pink is a synthetic material called Rosadium that is meant to have all the benefits of its fiberboard predecessor, but with one huge benefit that the old fiberboard couldn’t deliver, no delamination.  This matrix is very easy to skive, has a large range of sizes, and has the wide base we have become accustomed to from its forefather.  Pink is a great choice for any material or length of run.

For most materials used in the folding carton industry the 1.75 calculation has been adopted by many suppliers and “tech guys” over the past few years.  Many companies now use this as their primary calculation for determining matrix sizes.  This calculation works well for most of the substrates we encounter, including recycled and coated stock.  By using the 1.75 you keep the channel tight and force the substrate to delaminate.  Delamination is the internal separation of the paper.  The more delamination you can create the more air/space you create, which in turn will give you a better crease.  Matrix contains the delamination into one area forcing the crease to form.

Most times when we run into thicker boards (.024 and up) we will determine the matrix size using the 2 x board thickness calculation and then immediately go to the next wider channel width.  This is especially true when dealing with clay coated recycled stock or digitally printed stock.  The reason for this is that using a narrow channel on this type of stock will not allow the crease to fold over smoothly.  One may have a “good looking” score with a narrow channel, but once they try to fold the stock there will be a good deal of memory and it will not fold over nicely.  The inside bead becomes too wide and the material can not fold over itself.  Once you start to force the fold you are at a large risk of creating cracking and mis-alignment of the glue flaps, etc.  By widening out the score you give the stock more room to fold properly, eliminating the memory issue.  It is important to not get over zealous with widening your scores, you don’t want to create too much stretch across your sheet causing other headaches.

Corrugated creasing is a perfect example of an instance where a wider score is better.  There are a few things to remember when creasing corrugated material.  First, the thickness one should use when determining matrix is the crush thickness.  Second, whenever possible try to cut from the outside of the sheet.  I know that this is not always possible, especially with B and C flute, but if one is cutting corrugated with a mounted sheet of any kind this will substantially reduce checking.  It has been our experience when dealing with E and F flute most times one can use the same set-up as a paperboard job and end up with excellent results.  One thing that we will often suggest is to keep the channel wide and raise the channel height when with the flute.  This in effect gives similar results to reduced bead by trapping more of the corrugation into one area and giving the material a more defined score.

Calculations

Shreiner Metal
1.75 x board caliper “a” + rule width “b” = channel width “w”
Board caliper “a” = channel depth

ShreinerProfile and Pink
1.75 x board caliper “a” + rule width “b” = “x”
Divide “x” by .0394 to determine the metric measurement for the channel width “w”.

Board Caliper = “a”

Divide “a” by .0394 to determine the metric measurement for the channel height.

Make it easy on yourself and use our Automatic Matrix Calculator.

Every day we run into companies that are dead set on .937 knife and .918 crease for all of their dies.  I am a firm believer in “if it’s not broken, don’t fix it”, but this is not what we recommend for crease rule in one’s die.  The general formula we use to determine crease rule height is (knife height – board thickness = crease rule height).  This is the formula for any mylar backed or one piece extruded matrix.  When dealing with metal base matrix one must remember to subtract an additional .005” to .007” to account shim height in the matrix.  One important thing to remember is, this is only a general rule.  Some instances require a diversion from the norm in order to get a good crease, for example, a die that has multiple creases and/or double creases may require a lower scoring rule.

The width of the scoring rule mainly depends on the thickness of the substrate.  For most lighter stocks, .008” – .020”, 2 point rule is sufficient.  Once you move to a heavier stock, .020” +, it may be more beneficial to move to a 3 or 4 point rule, depending on the situation.  We also recommend that when creasing thicker substrates one should compress the material a couple of thousandths.  One will actually be able to see the imprint of the score rule in the material.  By compressing the material you actually force the crease to form and the board to delaminate, which in turn gives you a better score.

Calculations

Shreiner Metal
cutting rule height “c” – board thickness “b”) – .009 “d” = crease rule height “a”

Shreiner Profile and Pink
cutting rule height “c” – board thickness “b” = crease rule height “a”

Follow the guidelines for choosing the correct matrix size.

Use “Reduced Bead Creasing”.  Reduced bead creasing is a method that has been used for many years.  Originally reduced bead required lowering and tightening the matrix and replacing the score rule with the next wider size.  What this did was it trapped more material in tighter space, causing more delamination and a better fold.  Over time we have broadened our thinking to include any method of creating more delamination by tightening the matrix channel to be considered reduced bead creasing.  We have found that keeping the channel tight is a good everyday practice to stop cracking before it starts.  Refer to the “Determining Matrix Size” section.

The goal is to create as much internal delamination or the substrate as possible.  Basically, the more air and space you can create when scoring the better your score will fold and the less memory your score will have.  We always recommend keeping your channel tight and trapping the matrix at the points of critical distance, sometimes increasing the height will help achieve this as well.  This will cause the substrate to stretch and lead to greater delamination and less memory in the substrate.  Don’t get too tight!  If the matrix edge is cutting through, the channel is too tight.
Check your score rule heights.  A lack of score rule will often times lead to cracking.  An easy way to determine if your score rule is to low is to look at your score right off the press.  When you hand fold the score the bead should look solid.  If the score looks “ropey” or like it is “falling” your score rule could be too low.  For choosing the correct score rule height refer to the “Determining Score Rule Height” section.
If cracking is occurring on press before the score is folded you could have too much score rule height.  This often occurs when the job in question has capacity scores, or when the job has many scores on a multiple cavity die.  It is beneficial to lower your score heights .005” in these situations to help eliminate lateral draw and on press cracking.

A common problem we run into with cylinder presses are the scores running through the cylinder want to blow out the first quarter to half inch off of the gripper.  Many attribute this to matrix problems, but in reality it is more than likely a bearer problem.  Obviously, most cylinder presses that are being used today have been around the block once or twice.  Bearers compress about .003” when the press is on impression. Over time the edges where the chase bearers meet the cylinder bearers wear down and begin to dip at that point of contact, causing more impression and gripper edge scores to crack or blowout.  How do you solve the problem?  The quick fix is to file down the first quarter to half inch of one’s creasing rule.  The long-term fix is to contact someone with experience working on these types of presses and have it fixed.

Cylinder presses require a different set-up than a high speed platen or clamshell.  One major aspect of a die for a cylinder press that is often overlooked is crease rule.  The crease rule that runs through the cylinder should always be .003” – .005” lower than the crease rule that runs across the cylinder.  This is due to the constant pressure applied to the crease rule running through the cylinder.  Often times we get calls from companies that complain about their scores through the cylinder cracking or blowing out.  In most cases this is a result of the die being set-up with one height of creasing rule instead of the two it should have.  By specing out a lower score through the cylinder companies should be able to save themselves some headaches on press.

Introduction

Reduced Bead Creasing, theorized and taught by international consultant Kevin Carey of Diecutting Information Exchange, is a process of producing scores, or folds in folding cartons, or other paperboard stock with smaller “beads” in which the outer layer of paperboard will experience less tension during the fold and resist the tendency to crack.  Improving the appearance and eliminating the cracking of creases in a folding carton or other printed, folded material has long been a goal of numerous printers and folding carton makers. One of the methods tried was to use a small creasing channel. When it worked, the process was adopted, but not defined as a new theory. It was just known to have worked on a particular job.

Theory

In order to create these smaller beads, it is necessary to decrease the critical distance, which is the distance between the rule’s edge of the matrix channel. It should be noted that as well as decreasing the critical distance, the depth of the channel is suggested to be one half the thickness of the board caliper.  The rule of thumb in the past has been to allow this critical distance to be at least equal to the thickness of the paperboard stock that is intended to be creased. By reducing this distance, the degree of internal delamination increases, allowing the layers of paperboard to be easily forced into a smaller channel, creating a smaller bead.  This procedure can be accomplished in two ways. One, by increasing the pointage, or thickness of the creasing rule, and two, by reducing the size selection of the matrix channel. There are obvious advantages to increasing the rule thickness, but where it is impractical, or not economical to change the entire creasing rule in a die, changing the matrix strips is an option.

Corrugated Creasing

It should be noted to accomplish creasing in corrugated materials, the process is entirely different. Board delamination does not occur in creasing corrugated. Rather an action of crushing the outer layers and the inner flutes occurs, which does not necessarily create an inner “bead” of material. However, under the right conditions, using a channel matrix, a bead can be formed. Because of the many variations and the basic structure of corrugated itself, it is almost impossible to set a standard channel width selection to accomplish reduced bead creasing. However, the use of creasing matrix in corrugated materials is becoming ever more popular as demands for more attractive packaging rise.

Conclusion

Reduced Bead Creasing is a problem-solving tool to be used in cases where cracking occurs during the folding process. For this tool to work in your application take all considerations into account. Board type, moisture content, operating conditions, and press conditions are just a few to keep in mind.

How to use reverse bend matrix is a question often asked by individuals doing work-and-turn jobs or tri-fold brochures.  Reverse bending is a process in which traditional matrix is replaced with a male element and the traditional crease is configured in such a way to act as the female channel.  Originally reverse bend was designed for use on corrugated materials, it was then decided that this principle could be applied to folding carton as well and it has caused many sleepless nights for matrix manufacturers since.  This product can be useful when used in the right way.  Unfortunately the “right” way is a bit unorthodox and usually more trouble than individuals are willing deal with.

For those of you who like a challenge here is the best method I have found for getting reverse bend to function properly when cutting SBS or container board.  For this particular article we will use the example of .008” SBS outlined in the question above.  First, you need to determine how wide you want your crease/nub to be.  In the case described above a traditional 2 point score would work best.  The nub, or male part of the reverse score should mirror that measurement as closely as possible.  The sizes for reverse score are limited and the smallest crease/nub offered is .8mm or .03152″.  The other sizes offered are 1.0mm (.0394”) and 1.5mm (.0591”).

Once you have determined the width of your nub/crease you will want to have an actual piece of the matrix in your hand before you make the die.  You will want your diemaker to take the measurements directly from the reverse bend to ensure that the crease rule/female channel is calculated properly.  At this point take the locator off of the reverse bend, you will not use it at any point, including make-ready.  This is very important, if you try to use the locator your crease on the finished product will be way too wide and you will not be able to attain the effect you are looking for.  The crease rules that form the channel should be 2 x the material thickness + the nub width to the inside edge of the crease, not the center of the crease.  The reason we use the measurement from the inside of the crease rule is to eliminate the effect the rounded top of the crease will have on the final score, the rounded portion of the crease will widen your score in the area of critical distance, thus producing a wider weaker score that could be subject to cracking.  For the .008” SBS used as our example the measurement would be .048″ (2 x .008 = .016 + .03152 = .04752).  A great trick here is to use flat crease as opposed to round crease.  The flat crease more closely resembles traditional matrix channel and the squared edges will promote a much more crisp crease bead.  Flat edge crease will certainly produce the best results, but always remember to double check your width calculations, if the score rules are too close you could create a shearing effect.

Next you will need to determine your crease rule height.  The calculation for this is very similar to using traditional matrix.  Just remember you will have to additionally subtract .015″ to account for the base height of the reverse bend.  The score rule height calculation is: knife height – substrate thickness – .015″ (reverse bend base thickness).  In our example the score rule would need to be .914 (.937 knife height – .008 paper thickness – .015 base thickness = .914)  To be safe I would drop the crease back to .910 to give yourself a bit of a cushion and then spot it up from there.

Now you are ready to go on press.  Remove the locator strip from the reverse bend, as we said earlier you will not use it.  Place a double sided adhesive tape, preferably similar to the thickness of your stock (a couple of strips may be needed), between the crease rules.  Generally double sided tape is around .004” thick.  Ideally if you can mirror the thickness of your substrate as closely as possible you should be able to center the matrix almost perfectly between the score rules.  Next place the matrix on top of the adhesive tape, centering it as best as possible, this is the most delicate step in the process  Run the press over and locate the matrix, remove the adhesive tape used for locating, and you are off to the races.

Shreiner has double crease matrix for many different center to center spacings, including 1/8″ and 1/4″. The common heights and widths for double crease are .4 x 1.0 and .45 x 1.3. Off-center matrix, in different channel widths can be used in combination with double crease or at any distance between rules.  Shreiner has the ability to custom off-center any size of matrix you may need for your application.

It is vital to the integrity of any style of Shreiner matrix to be stored in a climate controlled environment.  Keeping matrix in this type of environment will help it to last longer and run at it’s full capability.  Storing it in a hot humid environment will deteriorate the matrix adhesives and could cause problems when it is put on press.  Also it is important to remember the shelf-life for most matrix is 6-12 months.

Shreiner Matrix is sold by the box, with no minimum order.  There are price breaks available at the quantities of 5 and 26 boxes.

Shreiner Metal and Shreiner Profile with a channel width of 3.0 or less are sold in boxes containing 82.7 feet with 36 strips.

Shreiner Metal and Shreiner Profile with channel widths larger than 3.0 are sold in boxes containing 48.2 feet with 21 strips.

All sizes of Pink contain 117.5 feet per box.

Shreiner Rubba comes in precision strips to be placed along the knives to allow faster running, cleaner cutting, less dust and flaking and fewer, smaller nicks.  Shreiner D Nick Rubba, C-profile White Lightning and Power Trap® clamp the paper using their shape and strength to hold the nicks together and keep the paper from tearing after the knife has made its initial penetration into the material. Also, Shreiner Rubba has no holes which tend to dry out during the run, and while the die is stored between runs. So Shreiner Rubba maintains its “bounce” almost indefinitely, reducing the need to re-rubber dies. Also knife life is extended, since tonnage is not increased to compensate for hardening rubber during the run.

All Shreiner rubber comes with fool proof spacing features to help eliminate deflection. Whether it is a trapezoid shape, hourglass shape, or built in spacing shelf you will find it easy to place your rubber with consistent 1/16” spacing away from your knife.

Checking and flaking is usually caused by lateral draw across the sheet.  Shreiner has developed two types of profile rubber to combat this.  First is our D profile rubber.  D profile couples more surface area with a rolling clamp motion to help seat the sheet.  By gripping and seating the sheet  D profile will help eliminate the tearing of the sheet edge when lateral draw occurs.  D profile comes in two different densities to accommodate those cutting paperboard and those cutting corrugated.

For more extreme circumstances where the lateral draw is too much D profile to handle, Shreiner can offer C profile.  C profile has enlarged surface area for maximum gripping of the sheet.  C profile also combines the maximum gripping action with a slighter rolling motion, insuring that lateral draw will not affect the sheet edge.  As with D profile, C profile comes in two different densities for paperboard and corrugated cutting.

Shreiner D profile is specially designed for the purpose of preventing nicks from blowing out.  Shreiner D profile is a 60 durometer rubber that clamps and rolls in nicking areas preventing lateral draw and/ or diecutting pressure to blow out the nicks.  D profile will allow you to run your job with less nicking and smaller ties.  It is important to remember to nick the rule prior to placement of the rubber.  If you nick through the rubber you will compromise the integrity of the rubber and it will not be able to fully perform its function.

Shreiner has several profiles of thin ejection strips available to eject slots, gutters and double knives.  T-rubba has a small shelf at the bottom to allow space for the rubber to expand without “blowing out” the rule. Power Trap® for slots is trapezoidal shaped. Slot Rubba is hourglass shaped to also provide relief.

Shreiner Punch Out is available for any base size up to 1 1/2”, as well as, most hanger-hole style punches. Far superior to springs, Punch Out will not snag the sheet as it runs through the press and is extremely easy to use.  Shreiner can cut the Punch Out for any height punch you may need.