Sunday, 30 October 2011

What is design for print?//Trapping/Knock Out/Overprinting.

Researching specific information on trapping, knock out and overprinting methods used in professional print production. All research will help to generate both general knowledge and content for my ISSUU based publication in which I will explore and note useful tips and information for designing for print- the development of which can be found on my Design Practice blog over the forthcoming days and weeks.


Trap (printing)

without trapping
with trapping

Comparison of a knock-out with and without trapping, and overprinting for perfect and imperfect registration. 
Rows are as follows:
1. The cyan (lighter) plate,
2. The magenta (darker) plate,
3. Result with perfect registration (some monitors show slight misalignment), and
4. Result with imperfect registration.

Trapping is a term most commonly used in the prepress industry to describe the compensation for misregistration between printing units on a multicolor press. This misregistration causes unsightly gaps or white-space on the final printed work. Trapping involves creating overlaps (spreads) or underlaps (chokes) of objects during the print production process to eliminate misregistration on the press.


Misregistration in the graphical workflow may be caused by a number of reasons:
  • inaccuracies in the image setter
  • instability of the image carrier, eg stretch in film or plate
  • inaccuracy in the film to plate or film to film copying steps
  • instability of the press
  • instability of the final media
  • human error
These inaccuracies are inherent to the graphical production process and although they can be minimized they will never completely disappear - any mechanical process will always show some margin of error. The small gaps showing up as a result can however be hidden by creating overlaps between two adjacent colors.

Trapping methods

One approach to trapping is to change the submitted artwork. In general, all digital files produced using any current professional software have some level of trapping provided already, via application default values. Additional trapping may also be necessary, but all traps should be as unobtrusive as possible.
Traps can be applied at several stages in the digital workflow, using one of two trapping technologies: vector-based and raster-based. The right choice will depend on the type of products (packaging applications including flexo-printing have other requirements than commercial printing on offset systems) and the degree of interactivity or automation that is wanted.
In-RIP trapping moves the trapping to the RIP so that it is done at the last moment. The process is automatic, though it is possible to set up zones to allow different automatic rules for different areas, or to disable trapping for areas previously manually trapped.

Trapping decision making

Certain basic rules have to be observed.
First the decision should be made if a trap is needed between two specific inks, in other words, if these two abutting colors are printed is there a risk of gaps showing up when misregistration happens.
In case the two colors in question are spot colors, trapping is always needed: from the moment the artwork is imaged on film or plate, they are handled separately and ultimately will be printed on two different printing units. The same applies if one of the colors is a spot, the other a process color.
The decision becomes a bit more tricky if the two colors are process colors and will each be printed as a combination of the basic printing colors Cyan, Magenta, Yellow and Black. In this case the decision whether to trap or not will be defined by the amount of ‘common’ color.
Another factor that will influence the visibility of the traps is the direction of the trap. The decision which color should be spread or choked is usually decided upon the relative luminance of the colors in question. The ‘lighter’ color should always be spread into the darker. Again this reflects the way the human eye perceives color: since the darker colors define the shapes we see, distortion of the lighter color will result in less visible distortion overall. The ‘lightness’ or ‘darkness’ of a color is usually defined as its ‘neutral density’.
A major exception to this rule should be applied when opaque spot colors are used. Other colors, regardless of the relative luminance should always be trapped to (spread under) these spot colors, If several of these spot colors are used (a common practice in the packaging market), it is not the luminance of the color but the order of printing that will be the decisive element: the first color to be printed should always spread under the next color.

Example use of a trap.
The thinner the traps created, the less visible they will be. Therefore the trap width should be set to the strict minimum, dictated by the maximum amount of misregistration or error margin of the whole production workflow up to the printing press. Since the printing technology and the quality of the paper are the most important causes for misregistration it is possible to come up with some rules of thumb. E.g. for quality offset printing it is generally accepted that the trapping width should be between 1 and 1/2 print dots. When printing at 150 lpi the traps should be between 1/150 and 1/300 inch. (0.48 pt. and 0.24 pt., 0.16 mm. and 0.08 mm.). These values are usually multiplied with a factor of 1.5 or 2 whenever one of the colors is Black. First of all the trap will not be visible since the lighter color will be spread underneath the -almost- opaque black. For the same reason, in many cases, black ink will be set to "overprint" colors in the background, eliminating the more complex process of "spreading or choking". Since black is a very dark color, white gaps caused by misregistration will be the more visible. On top of that -in wet-in-wet offset printing- black is the first color to be laid down on paper, causing relatively more distortion of the paper and thus at higher risk of showing misregistration.
Whenever a trap between two colors is created this trap will contain the sum of the two colors in question whenever at least one of them is a spot color. In case the two colors are process colors, the trap will contain the highest value of each of the CMYK-components. This trap color is always darker than the darker of the two abutting colors. In some cases, more specifically when the two colors are light pastel-like colors, this might result in a trap that is perceived as too visible, In this case it might be desirable to reduce the amount of color in the trap. This should however be limited: the trap should never be lighter than the darkest color since this would have the same effect as misregistration: a light colored ‘gap’ between the two colors. Trap color reduction is also not recommended when solid spot colors are used. In this case reduction would cause the spot color in the trap to be printed not as a solid but as a screened tint.
Trapping towards a rich black (a black with a support screen of another color added to it to give it a ‘deeper’ look and making it more opaque - often called "undercolor" ), will follow the same rules as trapping to a ‘normal’ black. However, a stay-away should be created for the supporting color. This will prevent misregistration from revealing the undercolor at the edges of the rich black object. In short, a stay-away pushes the undercolor away from the edge of the rich black, and is usually created with a single color black stroke, set to "knock-out".
Blends or ‘vignettes’ often offer special challenges to trapping. The lighter part of a blend needs to spread into the background, the darker part needs to be choked. If a trap over the full length of the blend is needed, this would result in a very visible ‘staircase’. The solution here is the creation of a sliding trap: a trap that should not only gradually change color but also position. The trap can be created so that it ‘slides’ all the way, but this not often the desired effect either since it might distort the original artwork too much. Often the ‘sliding’ factor is set to a point where the neutral densities of blend and background reach a certain difference.


without trapping
with trapping

Comparison of a knock-out with and without trapping, and overprinting for perfect and imperfect registration. 
Rows are as follows:
1. The cyan (lighter) plate,
2. The magenta (darker) plate,
3. Result with perfect registration (some monitors show slight misalignment), and
4. Result with imperfect registration.

Overprinting refers to the process of printing one colour on top of another in reprographics. This is closely linked to the reprographic technique of 'trapping'. Another use of overprinting is to create a rich black (often regarded as a color that is "blacker than black") by printing black over another dark colour.
It is also the term used in the production of envelopes customised to order by printing images (such as logos) and texts (such as slogans) on mass-produced machine-made envelopes; the alternative way of producing such envelopes is to print "on the flat" and then cut out the individual shapes and fold them to form the envelopes. However the latter method is generally only economically viable for large print runs offering returns to scale.

1. Commercial printing: Process of creating slight overlap between abutting colors of a multicolor job in commercial (multipass) printing machines, to compensate for errors in registration of color plates. No trapping is required in inkjet (and other single pass) printing because there are no registration problems.

Preparing color documents for commercial printing

You can print each page of a document as a series of color separations. Color separating splits color images into several pages. Each page contains one component color. A commercial printer uses the separations to make printing plates, one for each color.
You can also print mirror and negative images, which is sometimes required when commercially printing to film.
If color objects overlap in your document, you can overprint. Overprinting prints an object (most often a dark one) on top of another color object. You can also create a knockout, in which the top color is printed but colors behind it are not. You can use trapping to ensure that no gap exists between objects.

Print color separations

When you print color separations, choose which colors to print as spot colors, which to print as process colors, and which not to print at all. Text and graphic objects are printed in black for each separation, with shades of gray indicating the percentages of color saturation. The color name of each separation is printed outside the registration marks (if registration marks are on and if there’s room on the page).
Note: For best results, print CMYK colors as process rather than spot-color inks. You can check plate assignments in the Separations Setup dialog box (File > Print and click Separations Setup).
Composite image
Black separation
Spot color separation
Imported color graphics are separated if they are in CMYK, TIFF, DCS, or EPS line art format. Also, bitmap images in EPS graphics can be separated as long as they can also be separated in Adobe Illustrator.
You can also separate a document by printing to a single PostScript file and then having a commercial printer separate the file for you.
Make sure that spot colors with identical definitions have the same names. Spot colors with the same definition but with different names appear on different plates when you print color separations.
Process color separations are printed using grids of black dots for each color—the larger the dots, the more color is printed. The halftone screen settings control how close together the dots appear, the orientation of the grid (the screen angle), and the dot shape. For information, consult your printer documentation and your commercial printer.

Creating color separations

  1. Make sure that you have not set colors to print as black and white instead of shades of gray.
  2. Choose File > Print.
  3. Choose an option from the Registration Marks pop-up menu.
  4. To print all pages for one plate and then all pages for the next plate, deselect Collate. Select Collate to print all plates for one page before printing all plates for the next page, and so on.
  5. Click Separations Setup. If necessary, move the color names to the appropriate scroll lists and click Set. To move a color, double-click the color. To move all colors, select a color in the list and Shift-click an arrow.
    Tints do not appear in this dialog box; they print on the same plate as the base color.
    If your printer can’t print process color separations, the dialog box contains only the Print As Spot and Don’t Print scroll lists. The scroll list where each color appears by default depends on how the color was defined on its Print As setting.
  6. To specify halftone screen settings, click Halftone Screens, adjust the settings, and then click Set.
  7. In the Print dialog box, select Print Separations, set the remaining print options as necessary, and then click Print.

Knock out and overprint colors

When one color object overlaps another, FrameMaker normally knocks out the overlapped portion so that it does not print in a color separation. It appears as the color of the paper. If you’re producing color separations and printing commercially, registration errors sometimes occur, and small gaps between colors appear.
Accurate and inaccurate registration
To avoid gaps between colors, you can apply overprinting to the top object so that the overlapped portion is not knocked out.
Knocked out (left) and overprinted (right)
You can also use overprinting to combine two colors for special effects.

Knock out or overprint all objects of a particular color

  1. Define a color.
  2. To make this color print on top of other colors when printing separations, do one of the following:
    • To have any object that uses this color overprint, choose Overprint.
    • To have any object that uses this color knock out, choose Knock Out.

Apply knock out or overprint to objects

  1. Select the object and open the Tools palette or choose Graphics > Object Properties.
  2. Choose one of the following from the Overprint pop-up menu:
    • To have this object overprint objects beneath it, choose Overprint.
    • To have this object knock out objects beneath it, choose Knock Out from.
    • To have this object use the overprint setting defined for the color, choose From Color. This option is the recommended setting.

Overprinting images created in other applications

If you want images created in other applications to overprint other objects when printed from FrameMaker, note these special cases:
  • CMYK TIFF files overprint objects on spot color plates under all of the following conditions: if printed as separations, if their Overprint attribute is set to True, and if their Fill property is set to None.
  • EPS files do not overprint other objects when printed as separations.

Print negative and mirror images

Your commercial printer sometimes asks you to print negative images in which all text and objects are inverted when you submit printing files on film. Sometimes you print flipped images with the emulsion side down. Emulsion is the photosensitive substance on the film surface. These flipped images mirror the normal appearance of the pages.
Note: Sometimes the settings differ depending on the printer driver you’re using, and are unavailable with non-PostScript printer drivers.
 Choose File > Print Setup. Click Properties to access the printer driver options. Locate and set the options that control negative and mirror images.

Trap objects

In commercial printing, overprinting to compensate for registration errors sometimes produces unacceptable color mixing. In this case, perhaps you trap the object instead of overprinting it. A trap is a line bordering the object on top. It is wide enough to fill the color gap and to overprint the other object along the border of its cutout.
Without trapping and with trapping
Having a commercial printer trap your documents saves you the effort of hand-trapping each object individually. Also, manual trapping sometimes must be undone if you later decide to have a commercial printer do the trapping.
  1. Create a border for the object on top by duplicating the object and setting the duplicate fill pattern to None. Be sure that the duplicated object is exactly over the original.
  2. Set the line width of the border as appropriate. Consider the size and contour of the object, the type of printing paper, and the accuracy of the printing press. Consult your commercial printer for information on suitable line widths for trapping.
    The stroke of a line is always centered on an object edge. Therefore, double the line width specification that the commercial printer gives you.
  3. Select the border and choose Overprint from the Tools palette.

Processing color documents using OPI

You can have a document color separated, or have all objects in a document or book trapped by printing to a PostScript file. Then have a commercial printer process the PostScript file for you. Creating a PostScript file in this way embeds instructions in the file. These instructions conform to the Adobe Document Structuring Convention (DSC). DSC enhances the performance of postprocessing products that perform trapping and imposition. DSC also lets you take full advantage of products that support Open Prepress Interface (OPI) version 1.3. OPI reduces the hardware overhead for working with high-resolution color images.
OPI-enhanced PostScript files contain information that the commercial printer software uses to match the placeholder images with the high-resolution ones at print time.
Note: Before beginning, ask your commercial printer for any special instructions for producing PostScript files.
  1. Ask your service bureau or commercial printer to make high-quality scans of your artwork and keep the high-resolution images. You take the OPI-ready low resolution EPS or TIFF versions of the images to work with.
  2. Import (by reference or by copying) the low resolution images into your document.
  3. Create a print file, or a series of print files for a book.

Printing to Linotronic typesetters

Here are some tips for printing to Linotronic typesetters:
  • Some Linotronic typesetters automatically place registration marks on the page. Check with your service bureau to see whether to use the Registration Marks setting when you print.
  • Not all Linotronic models support thumbnails. Test various thumbnail settings to find the optimum setting. Some Linotronic models print 1 x 2 thumbnails correctly, but not 2 x 2 thumbnails.
  • Some Linotronic drivers fail to let you enter a custom paper size even after you have chosen User Defined Size in the Paper Size pop-up menu. To enter a custom paper size, right-click the Linotronic driver and choose Properties. Click the Paper tab, and then select the custom paper size icon from the scroll list of icons.

What is design for print?//Colour separations.

Researching specific colour separation information in order to build and develop a substanial basis of knowledge for the content of my ISSUU- based "what is design for print?" manual publication. Image examples and definitions will help towards the development, as well as being additions to the manual itself. All design developments for the project can be found within the forthcoming days and weeks on my Design Practice blog.


Web definitions
  • Color printing or Colour printing is the reproduction of an image or text in color (as opposed to simpler black and white or monochrome printing). ...

  • (Colour separations) The process of preparing artwork, for printing by separating into the four primary printing colours, CMYK.

  • (Colour separations) the division of a multi-coloured original or line copy into the basic (or primary) process colours of yellow, magenta, cyan and black. These should not be confused with the optical primaries, red, green and blue.

  • (COLOUR SEPARATIONS) are the 4 pieces of film negatives used in the production of making the photomechanical printing plates (See above)

  • (Colour separations) Originals which have been separated to identify spot colour differences within the specifications i.e. one original with spot colour headings only, the other with the body of text only
Definition: Color separation is the process by which original artwork is separated into individual color components for printing. The components are cyan, magenta, yellow and black, known as CMYK. By combining these colors, a wide spectrum of colors can be produced on the printed page. In this four color printing process, each color is applied to a printing plate. When the colors are combined on paper (they are actually printed as small dots), the human eye combines the colors to see the final image. The use of plates for printing is part of the process known as lithography.
Also Known As: Four-color Process
Common Misspellings: Color Seperation
The act of decomposing a color graphic or photo into single-color layers. For example, to print full-color photos with an offset printing press, one must first separate the photo into the four basic ink colors: cyan, magenta, yellow, and black (CMYK). Each single-color layer is then printed separately, one on top of the other, to give the impression of infinite colors.
This type of color separation, mixing three or four colors to produce an infinite variety of colors, is called process color separation. Another type of color separation, called spot color separation, is used to separate colors that are not to be mixed. In this case, each spot color is represented by its own ink, which is specially mixed. Spot colors are effective for highlighting text but they cannot be used to reproduce full-color images.
Traditionally, process color separation has been performed photographically with different colored filters. However, many modern desktop publishing systems are now capable of producing color separations for graphics stored electronically. This capability is essential if you want to create full-color documents on your computer and then print them using an offset printer. You don't need to perform color separation if you are printing directly to a color printer because in this case the printer itself performs the color separation internally.

Color separation process

The process of color separation starts by separating the original artwork into red, green, and blue components (for example by a digital scanner). Before digital imaging was developed, the traditional method of doing this was to photograph the image three times, using a filter for each color. However this is achieved, the desired result is three grayscale images, which represent the red, green, and blue (RGB) components of the original image:
The next step is to invert each of these separations. When a negative image of the red component is produced, the resulting image represents the cyan component of the image. Likewise, negatives are produced of the green and blue components to produce magenta and yellow separations, respectively. This is done because cyan, magenta, and yellow are subtractive primaries which each represent two of the three additive primaries (RGB) after one additive primary has been subtracted from white light.
Cyan, magenta, and yellow are the three basic colors used for color reproduction. When these three colors are variously used in printing the result should be a reasonable reproduction of the original, but in practice this is not the case. Due to limitations in the inks, the darker colors are dirty and muddied. To resolve this, a black separation is also created, which improves the shadow and contrast of the image. Numerous techniques exist to derive this black separation from the original image; these include grey component replacement, under color removal, and under color addition. This printing technique is referred to as CMYK (the "K" being short for "key." In this case, the key color is black).
Today's digital printing methods do not have the restriction of a single color space that traditional CMYK processes do. Many presses can print from files that were ripped with images using either RGB or CMYK modes. The color reproduction abilities of a particular color space can vary; the process of obtaining accurate colors within a color model is called color matching.

What is design for print?//Laminate.


noun /-nit/  /-ˌnāt/ 
laminates, plural
  1. A laminated structure or material, esp. one made of layers fixed together to form a hard, flat, or flexible material

verb /ˈlaməˌnāt/ 
laminated, past participle; laminated, past tense; laminates, 3rd person singular present; laminating, present participle
  1. Overlay (a flat surface, esp. paper) with a layer of plastic or some other protective material

  2. Manufacture by placing layer on layer

  3. Split into layers or leaves

  4. Beat or roll (metal) into thin plates

adjective /-nit/  /-ˌnāt/ 
  1. In the form of a lamina or laminae

Web definitions
  • create laminate by bonding sheets of material with a bonding material

  • a sheet of material made by bonding two or more sheets or layers

  • press or beat (metals) into thin sheets

  • cover with a thin sheet of non-fabric material; "laminate the table"

  • (lamination) a layered structure

  • (lamination) bonding thin sheets together

A laminate is a material that can be constructed by uniting two or more layers of material together. The process of creating a laminate is lamination, which in common parlance refers to the placing of something between layers of plastic and gluing them with heat and/or pressure, usually with an adhesive. However, in electrical engineering, lamination is a construction technique used to reduce unwanted heating effects due to eddy currents in components, such as the magnetic cores of transformers.


There are different lamination processes, depending on the type of materials to be laminated. The materials used in laminates can be the same or different, depending on the processes and the object to be laminated. An example of the type of laminate using different materials would be the application of a layer of plastic film — the "laminate" — on either side of a sheet of glass — the laminated subject.
Vehicle windshields are commonly made by laminating a tough plastic film between two layers of glass. Plywood is a common example of a laminate using the same material in each layer. Glued and laminated dimensioned timber is used in the construction industry to make wooden beams, Glulam, with sizes larger and stronger than can be obtained from single pieces of wood. Another reason to laminate wooden strips into beams is quality control, as with this method each and every strip can be inspected before it becomes part of a highly stressed component such as an aircraft undercarriage.
Examples of laminate materials include Formica and plywood. Formica, which refers to a specific brand name of materials by its manufacturer with the same name, and similar plastic laminates are used in the production of decorative laminates, using either a high or low pressure thermo-processing system. Decorative laminates (such as Maica Laminates, Wilsonart or Laminart) are produced with kraft papers and decorative papers with a layer of overlay on top of the decorative paper, set before pressing them with thermoprocessing into high-pressure decorative laminates. A new type of HPDL is produced using real wood veneer or multilaminar veneer as top surface. Alpikord produced by Alpi spa and Veneer-Art, produced by Lamin-Art are examples of these types of laminate. High-pressure laminates consists of laminates "molded and cured at pressures not lower than 1,000 lb per sq in. (70 kg per sq cm) and more commonly in the range of 1,200 to 2,000 lb per sq in. (84 to 140 kg per sq cm). Meanwhile, low Pressure laminate is defined as "a plastic laminate molded and cured at pressures in general of 400 pounds per square inch (approximately 27 atmospheres or 2.8 x 106 pascals).
Laminating paper, such as photographs, can prevent it from becoming creased, sun damaged, wrinkled, stained, smudged, abraded and/or marked by grease, fingerprints and environmental concerns. Photo identification cards and credit cards are almost always laminated with plastic film. Boxes and other containers are also laminated using a UV coating. Lamination is also used in sculpture using wood or resin. An example of an artist who used lamination in his work is the American, Floyd Shaman.
Further, laminates can be used to add properties to a surface, usually printed paper, that would not have them otherwise. Sheets of vinyl impregnated with ferro-magnetic material can allow portable printed images to bond to magnets, such as for a custom bulletin board or a visual presentation. Specially surfaced plastic sheets can be laminated over a printed image to allow them to be safely written upon, such as with dry erase markers or chalk. Multiple translucent printed images may be laminated in layers to achieve certain visual effects or to hold holographic images. Many printing businesses that do commercial lamination keep a variety of laminates on hand, as the process for bonding many types is generally similar when working with arbitrarily thin material.


Lamination was invented by Dr. Morris M. Blum, DDS, a dentist in 1938. Although it may sound surprising, it turns out that dental laminate was the inspiration for the first lamination of a photograph. Dr. Blum used clear resin that was normally used for capping and bonding teeth to laminate a photograph of his wife. He is recognized to this date for his contributions with a special scholarship fund at the University of Minnesota.

Types of laminators

Three types of laminators are used most often in digital imaging:
  • Pouch laminators
  • Heated roll laminators
  • Cold roll laminators

Film types

Laminate film is generally categorized into these five categories:
  • Standard thermal laminating films
  • Low-temperature thermal laminating films
  • Heatset (or heat-assisted) laminating films
  • Pressure-sensitive films
  • Liquid laminate

What is design for print?//Die Cutting.

Researching information about the die cut print finish technique for developing my own specific content for my ISSUU- based design for print publication. I hope this research will give me a full, fluent understanding of the finish and process of die cutting in a professional environment. Developments of this project can be found on my Design Practice blog over the upcoming days and weeks.,or.r_gc.r_pw.,cf.osb&fp=dda4e66ed3be77a4&biw=1280&bih=635


  • Shearing, also known as die cutting, is a metalworking process which cuts stock without the formation of chips or the use of burning or melting. ...

  • Die cutting is the process of using a die to shear webs of low strength materials, such as rubber, fiber, cloth, paper, corrugated fiberboard, paperboard, plastics, pressure sensitive adhesive tapes, foam and sheet metal. ...

  • A method of using sharp steel ruled stamps or rollers to cut various shapes i.e. labels, boxes, image shapes, either post press or in line. The process of cutting paper in a shape or design by the use of a wooden die or block in which are positioned steel rules in the shape of the desired pattern.

  • Process of using sharp metal rules on a wooden block to cut out specialised shapes such as pocket folders or unusual shaped flyers etc.

  • Curing images in or out of paper.

  • Using a die to cut paper. For example, it is commonly used for cutting slits for business cards to be inserted on a booklet or folder

  • cutting custom shapes out of a piece of paper using a "die" made with sharp metal-edged rules that have been mounted onto wood.

  • The method of using sharp edged cutting dies to cut out shapes from a wide array of soft to semi-rigid materials. The action of making piece parts from bulk materials using cutting dies and presses.

  • A method of using sharp steel ruled stamps or rollers to cut various shapes i.e. labels, boxes, image shapes, either post press or in line.

  • uses a wooden die with metal (in the shape of the piece). It is placed on a letterpress and the paper is pressed onto the die and cut into the desired shape.

  • The process of using sharp steel rules to cut special shapes into printed sheets.

  • Cutting irregular shapes in paper using metal rules mounted on a letter press.

Die cutting is a manufacturing process used to generate large numbers of the same shape from a material such as wood, plastic, metal, or fabric. The die cut shapes are sometimes called “blanks,” because they are usually finished and decorated before being sold. The process is widely used on an assortment of materials all over the world, and many manufactured products contain several die cut components, often assembled together in a series of steps to create a finished product.
Sharp specially shaped blades are used in die cutting. The blade is bent into the desired shape and mounted to a strong backing. The result is known as a die. The material being cut is placed on a flat surface with a supportive backing, and the die is pressed onto the material to cut it. Depending on what is being made, a single die might cut one piece of material, or it might be designed to slice through multiple layers, generating a stack of blanks.
Many consumers find it helpful to consider a cookie cutter when thinking about die cutting. The cookie cutter is a type of die which is capable of cutting out a potentially infinite amount of blanks. Each blank will be exactly the same shape and size, meaning that the blanks can be cooked uniformly together and decorated at will for individuality. The alternative is cutting out each cookie by hand, a painstaking process which would result in irregular final products.

Die (manufacturing)

A die is a specialized tool used in manufacturing industries to cut or shape material using a press. Like molds, dies are generally customized to the item they are used to create. Products made with dies range from simple paper clips to complex pieces used in advanced technology.

Die forming

Progressive die with scrap strip and stampings
Forming dies are typically made by tool and die makers and put into production after mounting into a press. The die is a metal block that is used for forming materials like sheet metal and plastic. For the vacuum forming of plastic sheet only a single form is used, typically to form transparent plastic containers (called blister packs) for merchandise. Vacuum forming is considered a simple molding thermoforming process but uses the same principles as die forming. For the forming of sheet metal, such as automobile body parts, two parts may be used, one, called the punch, performs the stretching, bending, and/or blanking operation, while another part, called the die block, securely clamps the workpiece and provides similar, stretching, bending, and/or blanking operation. The workpiece may pass through several stages using different tools or operations to obtain the final form. In the case of an automotive component there will usually be a shearing operation after the main forming is done and then additional crimping or rolling operations to ensure that all sharp edges are hidden and to add rigidity to the panel.

Die components

The main components for Die Toolsets are:
  • Die block - This is the main part that all the other parts are attached to.
  • Punch plate - This part holds and supports the different punches in place.
  • Blank punch - This part along with the Blank Die produces the blanked part.
  • Pierce punch - This part along with the Pierce Die removes parts from the blanked finished part.
  • Stripper plate - This is used to hold the material down on the Blank/ Pierce Die and strip the material off the punches.
  • Pilot - This is used to keep the material being worked on in position.
  • Guide / Back gage / Finger stop - These parts are all used to make sure that the material being worked on always goes in the same position, within the die, as the last one.
  • Setting (Stop) Block - This part is used to control the depth that the punch goes into the die.
  • Blanking Dies - See Blanking Punch
  • Pierce Die - See Pierce Punch.

Die operations and types

Die operations are often named after the specific type of die that performs the operation. For example a bending operation is performed by a bending die. Operations are not limited to one specific die as some dies may incorporate multiple operation types:
  • Bending: The bending operation is the act of bending blanks at a predetermined angle. An example would be an "L" bracket which is a straight piece of metal bent at a 90° angle. The main difference between a forming operation and a bending operation is the bending operation creates a straight line bend (such as a corner in a box) as where a form operation may create a curved bend (such as the bottom of a drink can).
  • Blanking: A blanking die produces a flat piece of material by cutting the desired shape in one operation. The finish part is referred to as a blank. Generally a blanking die may only cut the outside contour of a part, often used for parts with no internal features.
    Three benefits to die blanking are:
  1. Accuracy. A properly sharpened die, with the correct amount of clearance between the punch and die, will produce a part that holds close dimensional tolerances in relationship to the parts edges.
  2. Appearance. Since the part is blanked in one operation, the finish edges of the part produces a uniform appearance as opposed to varying degrees of burnishing from multiple operations.
  3. Flatness. Due to the even compression of the blanking process, the end result is a flat part that may retain a specific level of flatness for additional manufacturing operations.
  • Broaching: The process of removing material through the use of multiple cutting teeth, with each tooth cutting behind the other. A broaching die is often used to remove material from parts that are too thick for shaving.
  • Bulging: A bulging die expands the closed end of tube through the use of two types of bulging dies. Similar to the way a chefs hat bulges out at the top from the cylindrical band around the chefs head.
  1. Bulging fluid dies: Uses water or oil as a vehicle to expand the part.
  2. Bulging rubber dies: Uses a rubber pad or block under pressure to move the wall of a workpiece.
  • Coining: is similar to forming with the main difference being that a coining die may form completely different features on either face of the blank, these features being transferred from the face of the punch or die respectively. The coining die and punch flow the metal by squeezing the blank within a confined area, instead of bending the blank. For example: an Olympic medal that was formed from a coining die may have a flat surface on the back and a raised feature on the front. If the medal was formed (or embossed), the surface on the back would be the reverse image of the front.
  • Compound operations: Compound dies perform multiple operations on the part. The compound operation is the act of implementing more than one operation during the press cycle.
  • Compound die: A type of die that has the die block (matrix) mounted on a punch plate with perforators in the upper die with the inner punch mounted in the lower die set. An inverted type of blanking die that punches upwards, leaving the part sitting on the lower punch (after being shed from the upper matrix on the press return stroke) instead of blanking the part through. A compound die allows the cutting of internal and external part features on a single press stroke.
  • Curling: The curling operation is used to roll the material into a curved shape. A door hinge is an example of a part created by a curling die.
  • Cut off: Cut off dies are used to cut off excess material from a finished end of a part or to cut off a predetermined length of material strip for additional operations.
  • Drawing: The drawing operation is very similar to the forming operation except that the drawing operation undergoes severe plastic deformation and the material of the part extends around the sides. A metal cup with a detailed feature at the bottom is an example of the difference between formed and drawn. The bottom of the cup was formed while the sides were drawn.
  • Extruding: Extruding is the act of severely deforming blanks of metal called slugs into finished parts such as an aluminum I-beam. Extrusion dies use extremely high pressure from the punch to squeeze the metal out into the desired form. The difference between cold forming and extrusion is extruded parts do not take shape of the punch.
  • Forming: Forming dies bend the blank along a curved surface. An example of a part that has been formed would be the positive end(+) of a AA battery.
  • Cold forming (cold heading): Cold forming is similar to extruding in that it squeezes the blank material but cold forming uses the punch and the die to create the desired form, extruding does not.
  • Roll forming: a continuous bending operation in which sheet or strip metal is gradually formed in tandem sets of rollers until the desired cross-sectional configuration is obtained. Roll forming is ideal for producing parts with long lengths or in large quantities.
  • Horning: A horning die provides an arbor or horn which the parts are place for secondary operations.
  • Hydroforming: Forming of tubular part from simpler tubes with high water pressure.
  • Pancake die: A Pancake die is a simple type of manufacturing die that performs blanking and/or piercing. While many dies perform complex procedures simultaneously, a pancake die may only perform one simple procedure with the finished product being removed by hand.
  • Piercing: The piercing operation is used to pierce holes in stampings.
  • Progressive die: Progressive dies provide different stations for operations to be performed. A common practice is to move the material through the die so it is progressively modified at each station until the final operation ejects a finished part.
  • Shaving: The shaving operation removes a small amount of material from the edges of the part to improve the edges finish or part accuracy. (Compare to Trimming).
  • Side cam die: Side cams transform vertical motion from the press ram into horizontal or angular motion.
  • Sub press operation: Sub-press dies blank and/or form small watch, clock, and instrument parts.
  • Swaging: Swaging (necking) is the process of "necking down" a feature on a part. Swaging is the opposite of bulging as it reduces the size of the part. The end of a shell casing that captures the bullet is an example of swaging.
  • Trimming: Trimming dies cut away excess or unwanted irregular features from a part, they are usually the last operation performed.
  • what do you call upper part of die and lower part of die..?

Steel-rule die

Steel-rule dies, also known as cookie-cutter dies, are used to cut sheet metal and softer webs, such as plastics, wood, cork, felt, fabrics, and cardboard. The cutting surface of the die is the edge of hardened steel strips, known as steel rule. These steel rules are usually located using saw-cut grooves in plywood. The mating die can be a flat pieces of hardwood or steel, a male shape that matches the workpiece profile, or it can have a matching groove that allows the rule to nest into. Rubber strips are wedged in with the steel rule to act as the stripper plate; the rubber compresses on the down-stroke and on the up-stroke it pushes the workpiece out of the die. The main advantage of steel-rule dies is the low cost to make them, as compared to solid dies; however, they are not as robust as solid dies, so they usually only used for short production runs.

Rotary die

In the broadest sense, a rotary die is a circular shaped die that may be used in any manufacturing field. However, it most commonly refers to circular shaped dies used to process soft webs, such as paper and cardboard. Two dies are used, one has cutting and creasing rules, while the other acts as the anvil. Rotary dies are faster than flat dies, but not as accurate.
The term also refers to dies used in the roll forming process.

Wire pulling

Wire-making dies have a hole through the middle of them. A wire or rod of steel, copper, other metals, or alloy enters into one side and is lubricated and reduced in size. The leading tip of the wire is usually pointed in the process. The tip of the wire is then guided into the die and rolled onto a block on the opposite side. The block provides the power to pull the wire through the die.
The die is divided into several different sections. First is an entrance angle that guides the wire into the die. Next is the approach angle, which brings the wire to the nib, which facilitates the reduction. Next is the bearing and the back relief. Lubrication is added at the entrance angle. The lube can be in powdered soap form. If the lubricant is soap, the friction of the drawing of wire heats the soap to liquid form and coats the wire. The wire should never actually come in contact with the die. A thin coat of lubricant should prevent the metal to metal contact.
For pulling a substantial rod down to a fine wire a series of several dies is used to obtain progressive reduction of diameter in stages.
Standard wire gauges used to refer to the number of dies through which the wire had been pulled. Thus, a higher-numbered wire gauge meant a thinner wire. Typical telephone wires were 22-gauge, while main power cables might be 3- or 4-gauge.