Converting and Finishing processes
Graphic Prepress
Basic characteristics of converting and finishing processes All printed matter needs to be converted and finished to a customer’s required format.The converting and finishing formats are numerous and varied, because of the wide range of products we require each day. This includes books for reading, reference, writing and recording, magazines and brochures for periodical reading, information and advertising, personalised mailing and packaging of all our daily requirements from food to entertainment. Printed material arrives in the converting and finishing area in two ways - folded signatures from a web printing press or in a majority of cases in flat sheet form. The finisher or converter transfers or shapes the printed matter into the required product. To achieve this they will need a variety of processes: cutting, folding, collating, then binding or holding the product together by a number of means. These include wire stitches, sewing thread, adhesives, and a variety of plastic and metal fasteners. Printing companies set up to service a particular market area and have their own finishing area aligned to that market. However, some printing companies may opt to specialise in print only and send the printed material to a finishing trade house for converting and finishing. No one print finishing area can be set up to convert and finish all printed products. Because of the wide range of converting and finishing requirements many machines are required for each process. The cost of equipment is considerable and needs to be utilised to justify expenditure. So printing companies that have print finishing areas purchase equipment to serve a particular market. A print finishing trade house would need to purchase a variety of converting and finishing machines to service a wide customer base.
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Converting and Finishing processes
Converting and finishing processes Guillotining Guillotining is the process of cutting substrate and there are three types of machines used in the converting and finishing area, guillotine, three knife trimmer and a single copy trimmer. Guillotine The guillotine, also referred to as a paper cutter, is an integral part of converting and finishing. It has one large cutting knife and is capable of cutting a considerable amount of paper at a time. The cutting action is a slice or cleave and capable of cutting up to 100mm. of paper at one time. The guillotine could be used a number of times during a particular job. For example paper may need to be cut or trimmed to suit the printing process. Then the converting and finishing process may require printed matter to be cut to a suitable size for further processing, trimming after collating or binding and cutting of substrates and materials which may be needed to complete the finishing process. Guillotines are manufactured in various sizes, i.e. 92cm, 115cm, 132cm. 180cm. and 200cm. These sizes relate to the width of the cutting area. Guillotine selection will depend on the sheet size of printing equipment to adequately handle the paper for trimming. Smaller guillotines are manufactured in various Guillotine photo courtesy Heidelberg Aust. sizes i.e. 87cm. 76cm. 55cm. 36cm. for use in the small offset area, in-plants and small binderies.In these companies paper is usually purchased pre cut with no need to cut full reams from the paper merchants.
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All modern guillotines are computerised. This allows the operator to program all the cutting sequences for a job and after each cut the backgauge (which determines the cut position), moves to the next position. These programs can be stored and recalled any time. The screen monitor will show the operator all the cut sequences, position of the existing cut size, the next position and in some cases when and where to turn the paper pile. Smaller guillotines operating in the small offset area may not have screen monitors but most do have the facility to record and store programs. All guillotines have safety light barriers for the protection of the operator. Product type: Cutting full reams of paper to size for the printing press, cutting printed sheets for the folding machine, materials for hand binding, books and magazines that have been bound. Trimming work direct for packing labels, letterheads, pamphlets etc. Three knife trimmer A three knife trimmer is used to trim books on three sides in one action. The cutting action is the same as that of the single knife guillotine, a slice or cleave action. This means it has the capacity to cut a pile of books up to 100mm. high. It has one knife to trim the foredge and two parallel knives at right angles to the foredge knife to trim the head and tail together. This trimming process cuts the fold edges of the completed book this enhances the finished product and also allows the opening of each page. There are two manufactured types of three knife trimmers, a stand alone and an in-line model. The stand alone model is manually operated whereas the in-line model is linked to a signature gathering, adhesive binding machine to produce square backed trimmed books and magazines automatically. Product type: Trimming and finishing of adhesive bound or square backed books, magazines, periodicals, booklets etc. on three sides. Also for trimming sewn book blocks before case binding. Saddlestitch books can also be trimmed on a stand alone three way trimmer.
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Single copy trimmer A single copy trimmer is used in line on a automatic saddlebinder which producers saddle stitched booklets and magazines. The folded signatures are fed from hoppers, gathered in order on a saddle chain, bound together by wire stitches and three way trimmed in the single copy trimmer. The foredge is cut first and the two parallel knives cut the head and tail together. This is a scissor action as it uses two knives per cut, an upper knife which comes down past a lower stationary knife. This restricts the capacity of the material to be cut and only a single copy up to a maximum of 10mm. thickness is possible Product type: Trimming and finishing of saddlestitched magazines, periodicals and booklets on an in-line process.
Cutting and creasing for packaging The packaging, fibreboard and carton manufacturing industry utilises converting and finishing processes to produce a vast array of products for the Australian and export market. Specialised shapes for labels and packaging are designed for functionality and consumer appeal. A cutting forme is created to perform the die cutting operation. The cutting process may take place in-line as part of the actual printing process, or as a post press operation. Flatbed cutting and creasing is used mainly in the solid board sector to process the carton blanks, so that they can be erected into a three dimensional shape. The cutting die for carton packaging may consist of cutting, creasing, perforating and scoring rules and ejection rubbers. There are three main types of machines which carry out cutting and creasing: • Platen - the impression or pressure is delivered over the entire forme. The flat forme is forced against a flat steel bedplate. • Flatbed cylinders - a flatbed carries the forme, employing a cylinder to impart the impression. Pressure is applied in small sections as the cylinder turns over the forme.
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• Rotary die cutting - has two cylinders geared together and in contact. One cylinder carries the cutting forme, and the other acts as the impression cylinder.
Folding Folding is the process of taking a printed sheet and transposing it into: • A folded signature with the imposition or pages lining up for further processing or to a finished size i.e. a mailing piece or brochure. • A packaging product. The folding process can be performed by hand or machine. Hand folding Hand folding as it implies is the process of folding a flat printed sheet of paper manually by hand. Hand folding is done for short run jobs where is uneconomical to set up a machine or producing one of jobs i.e. dummy copies and limited editions. Machine Folding There are two basic machine folding techniques, knife and buckle. The principal of the knife fold is that the sheet of paper travels to a stop where a timed knife pushes the sheet between two moving rollers to nip the fold. The principle of the buckle fold is that two rollers drive the sheet continuously to a set stop (size) in a buckle plate forcing the sheet to buckle or fold and continue on to the next fold. Folding machines for publishing There are two basic types of folding machines, the all buckle machine where all the folds are produced by the buckle principle and the combination which uses both the buckle and knife principles. Folding machines range from desk top machines for office mailings to large machines for folding full size printed sheets in the edition book producing market.
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• The all buckle folder is manufactured in unit form. Each unit is designed with buckle plates above and below, usually 2 above and 2 below, to produce four in-line folds. Folding machine manufacturers can offer more buckle plate folds per unit, for specialised products. The number of units required is governed by the particular work being produced. The folding units are mobile and can be arranged to run right angles to each other or in-line. They are very versatile because they can fold up or down and are suitable for folding difficult impositions. • The combination folder incorporates buckle plates usually 2 above and 2 below in the first folding area. This is followed by a centrally located knife fold at right angles to the buckle plate. Machines may be purchased with an additional right angle knife. The combination folder has restricted imposition limitations because the knife is in a fixed position and can only fold in a downward mode. It is a very good folder for the general printer for folding leaflets, brochures and book signatures. Folding and gluing machines for carton production After the carton has been cut and creased, the next stage of production is folding and gluing. This is done on a folding and gluing machine which folds the main panels of the carton and glues the glue lap. The machine will pre-fold the creases, apply glue to the glue lap and then press and deliver the carton blank ready for the client. Shaped bars and belts assist in folding along the second and third creases. The carton is then returned to a flat position, so that the adhesive can be applied along the glue lap. The second crease is now folded over, so that the glued seam meets its opposite side panel. The seam is then held under roller and belt pressure, for sufficient time for the glue to set. There is a wide variety of gluing machines, each built to perform different functions and have different capabilities. They range from basic straight line gluing machines (as mentioned), to machines that can perform complicated four and six corner collapsible boxes, crash bottom lock boxes and window facing.
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Types of folds Right angle Right angle folding is where the first fold is made on the long side of the sheet and all the following folds are made at right angles to the previous fold. This is the common fold for all book work. Letter fold A letter fold is when a sheet 8 page right angle is folded in three, inside its self. This is common to mailing pieces of A4 material folded to fit a DL envelope.
6 page letter fold
Parallel Parallel folding is when all the folds are parallel to each other. This is popular with advertising brochures and leaflets. Gate fold A gate fold is an 8 page parallel fold where the outside pages fold into the middle fold. This type of fold used to create a panoramic image and is popular with the advertising market. Product type: Folding of flat printed sheets into signatures for gathering, finishing direct ( no further finishing requirements) leaflets, folders, fliers etc.
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Converting and Finishing processes
Gathering / collating The assembling of printed matter into their correct order for converting and finishing is termed gathering or collating. This would be single leaves or folded signatures and the assembling means that the page numbers or impositions should follow in their correct sequence. This can be performed manually or by machine. Gathering and collating have two distinct meanings while performing the same function in assembling. • Gathering is the term given to sheets or signatures being placed in their correct order without optical checking. This is generally a machine operation where the operator places the printed material into hoppers in order. The material is then fed automatically in sequence to produce a completed book. • Collating is the term given to sheets or signatures being placed in their correct order and being optically checked while being gathered. This is manual gathering where each sheet is read or checked while being assembled. This process is necessary where numbered work is being gathered i.e. invoice, docket and receipt books. Machinery Gathering machines are usually referred to as folded signature gatherers for saddle stitching, adhesive binding and sewn book blocks. Machines that gather single leaves are referred to as single Gathering machine sheet gatherers, photo courtesy Currie & Co although manufacturers call them collators to distinguish them from signature gatherers. Through modern technology machine manufacturers can equip machines with electronic scanning devices to read the print image of each signature to determine that each signature is in its correct sequence. Product type: Gathering of loose leaves into required sets, securing of required sets by corner or side stitching, gather wire stitch, fold and foredge trim to produce booklets.
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Adhesive fastening Adhesives in carton production Most types of glues are used in the carton industry. The adhesive is applied by means of a wheel, pen or jet. The use of jet nozzles, applying large quantities of adhesive, is particularly useful on corrugated products. Adhesive fastening for publishing Adhesive fastening is the term used to describe any converting and finishing process which uses adhesive to create a bond e.g. tipping, case making, headbanding, spine lining, casing in, drawing on covers and adhesive binding. The expression ‘adhesive binding’ has been generally adopted in the printing industry as the term encompassing a number of binding techniques in which the binding agent is glue. Adhesive binding is also referred to as ‘perfect binding’. This may date from the early development of the technique, and promotional claims that it was a ‘perfect’ inexpensive alternative to thread sewn book. The process of adhesive binding is to gather folded signatures in order, the spine folds are cut off to transpose the pages into single leaves. The cut edge is roughed to expose the paper fibre and glue is applied under pressure. While the glue is still in a wet state, the cover is applied and nipped to the book block. When the glue has dried the book block can be trimmed to the required size. This form of binding can be produced manually for a small number of books, or on large in-line machines which automatically gather, cut the spine, apply hot melt adhesive, cover and trim the completed book. Burst binding is an adhesive binding process where the signature spines are not cut. Glue is applied to the signatures which have a notch cut into the spine during the folding process. Glue floods the notches to give a more effective finish. Product type: All types of limp, hard covered or other work requiring components to be joined by means of adhesive. Adhesive binding is a binding method often used for magazines, periodicals and booklets which have a limited life expectancy, and which are too thick to saddlestitch. It is a cheaper, but less durable alternative to thread sewing for both limp and hard covered bindings.
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Wire fastening Wire fastening is the term given to the converting or finishing of printed products with wire. There are three basic ways of printed matter being held together by wire - saddlestitching, side stitching or block stitching and spiral binding. Saddlestitching Saddlestitching comprises of folded signatures being gathered by inserting them and placed on a ‘v’ shaped chain or table. Wire from a spool is fed into a stitching head ,which automatically cuts the wire, forms it into an inverted ‘u’, it is then driven through the spine and clinched or closed on the inside. This form of binding in small quantities can be produced manually on a free standing wire stitching machine, then cut to size on the guillotine. For large volumes of saddlestitched magazines, fully automatic machines are available which gather, stitch and trim in-line. Manufacturers can supply a cover fold feed station, which folds a flat cover and gathers automatically. Optional parts for the stitching head are available to produce a loop stitch. This forms a loop or semicircle on the crown of the stitch, instead of a flat stitch. This is used for booklets to be placed in ring binders, instead of drilling holes in the book or magazine. Consideration must be given to the imposition layout of signatures for saddlestitched books as the signatures are inserted into each other. Product type: Saddlestitching is the most inexpensive and popular binding of a wide variety of magazines, periodicals, brochures and booklets. However saddlestitching is restricted to a book thickness of approx. 10mm.
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Sidestitching This is also known as block stitching and produces a square back book. This comprises of folded signatures or single leaves being gathered on top of each other and being placed flat on the stitching machine. Wire from a spool is fed into a stitching head, which automatically cuts the wire, forms it into an inverted ‘u’, it is then driven through the book block, close to the spine and clinched or closed on the other side. This form of binding in small quantities can be produced on a free standing wire stitching machine then trimmed to size on a guillotine. For large volumes of sidestitched books fully automatic are available which gather, side stitch, apply glue to the spine, draw on the cover around the spine then trim to size. Consideration must be given to the imposition layout of signatures or single leaves for a side stitched book as they are gathered on top of each other. Product type: A majority of books bound by this method are stationery books, that is books that are written in e.g., receipt books, delivery books, order books etc. Before the technical advances in hot melt adhesive binding, magazines and periodical which were to thick for saddlestitching were produced in this method. Spiral binding This is the process of binding single leaves together by a wire threaded through holes in the printed pages. This is completed in two parts by two separate machines one punches holes into the printed sheets and the other then threads the wire. Another wire binding process can be used that is similar to wire spiralling. Instead of wire threaded through the book block, a preformed double loop wire is nipped into the punched holes. The printed material could be made up in two ways. One would be for the printed sheets to be folded into signatures gathered in their correct sequence, trimmed on all four sides into loose leaves to the finished size. The other would be for the printed sheets to be cut to finished size then gathered.
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The gathered leaves plus covers are then placed on an automatic punching machine which punches the holes for the wire binding. The completed punched book is placed on the wire binding unit, which threads a wire through the punched holes and cuts the wire to correct length or nips the preformed double loop type. The imposition layout for spiral binding is the same as that of side stitching as the pages or signatures are gathered on top of each other. Product type: Any book that needs to have complete operability or lay flat for reference while performing a task. Cook books, service manuals, price lists, calendars, promotional material, sales manuals etc.
Embellishments The converting and finishing process may include a wide variety of embellishments including: • embossing • foil stamping • laminating • window facing • waxing • laser cutting.
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Review questions for converting and finishing processes Q1 Name the main type of product cut with a three knife trimmer. ............................................................................................................................ Q2 Name the main type of product cut with a single copy trimmer. ............................................................................................................................ ............................................................................................................................ Q3 List the three (3) main types of machines which carry out cutting and creasing for the packaging industry. ............................................................................................................................ ............................................................................................................................ ............................................................................................................................ Q4 Name the two basic types of folding machines for the publishing industry. ............................................................................................................................ ............................................................................................................................ ............................................................................................................................ ............................................................................................................................ Q5 Describe the advantage of having a product spiral bound. ............................................................................................................................ ............................................................................................................................ ............................................................................................................................
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