Die Cutting

Die Cutting from Global Cutting Technologies

By: Global Cutting Technologies  20/10/2009
Keywords: cutting, die cutting, cutting presses

   HYDRAULIC DIE CUTTING EXPLAINED   The term “die cutting” is loosely applied to many types of cutting process but in our sphere of application and activity it applies mainly to the cutting out of shapes from soft or semi-rigid materials.   The process itself is, in fact, very simple but the machinery to perform the process has become increasingly sophisticated.   The closest analogy is to imagine a hand-held pastry cutter being pressed by hand through a sheet of pastry.  For ‘pastry cutter’, think cutting die or tool.  For hand, think ‘cutting press’.   The advantages of the die cutting process are speed, accuracy, use of unskilled labour, material saving, relatively low cost tooling.   Tooling   The tooling is commonly referred to as a cutting die, cutting tool, cutting knife or cutting forme and these are available in three main types:                     Wood forme      -     Cutting blade to the shape required is set in a plywood backer.                     Strip steel           -     This is usually a heavier gauge steel, bent to the required shape, possibly with re-inforcing struts.                     Forged steel       -     This is a heavy duty construction where the highest precision is required, usually for long runs and also, usually, for harder materials.  It is also the most expensive.   Hydraulic Die Cutting Machines Or Presses - Principles   For many years now, the vast majority of cutting presses have been hydraulically powered to enable high cutting forces to be developed safely and quietly to cut the most demanding of jobs.   In simple terms, a motor drives a pump, which then delivers oil under high pressure to a hydraulic cylinder or cylinders, thus driving the cutting head down to effect the cut.   All hydraulic presses require two main settings to be made before commencing work – (a) adjustment to the ‘cutting stroke’ which determines the depth to which the cutting die penetrates after it has cut through the material and (b) adjustment to the ‘daylight’ which is the gap measured between the upper and lower platens after the cutting head has returned to top position.   Die cutting presses usually have a polypropylene, PVC or nylon cutting pad on the bed of the press for the cutting blade to cut against (like a chopping board) and this works well with most materials.  However, automatic systems may use a special nylon belt as a cutting barrier in order to make sure cut components feed out of the machine – this can avoid sticking or snagging of materials in the cutting area.   Kiss Cutting And Steel To Steel Cutting   The main exception to cutting onto a plastic cutting barrier is when steel to steel cutting is required and a specialized die cutting press is used to permit this.   The requirement usually arises if the material to be cut cannot be cut through or parted off cleanly due it its fibrous nature.  Cutting against a precision hardened and ground steel plate can often solve this problem but the cutting press must have additional depth control equipment, in the form of a precision mechanical positive stops, to ensure that the cutting blade literally ‘kisses’ the steel surface in order to avoid blade damage.   This type of press can also be finely adjusted in order to cut self adhesive materials which have a bottom carrier paper.  By careful adjustment of the mechanical stops, the end of the stroke cut position can be set to cut through the material but not the carrier paper.  In this way, the cut product remains on the carrier paper and is rewound for later peel off and dispensing.  This process is also call ‘kiss cutting’.   COMMON TYPES OF HYDRAULIC DIE CUTTING PRESSES AND PRINCIPAL FUNCTIONS   Swing Arm Cutting Press (Swing Beam)   The most widely used model with thousands in daily use.  For cutting sheets of material (including leather hides) with small cutting dies.  The operator manually places the cutting die onto the material, swings the arm or beam over the die, the press arm descends and presses the die through the material.   Travelling Head Cutting Press   These versatile machines use small to medium sized cutting dies to cut material which can be in sheet form, long lays, or direct from the roll.   The principle is just the same but the cutting head is motorized so that it will traverse from side to side within the press frame.  The operator manually positions the die on the material but uses controls to traverse the cutting head over the die and deliver the cut.   Materials can be up to 2 metres wide (or more) and are fed in through the rear of the press.   Automatic Travelling Head Cutting Press   For fully automatic operation, the cutting die is mounted on the head of the press.  The head and the feed system are programmed so that the head travels accurately from side to side, delivering cuts, and the feed system moves the material forward for each successive row of cuts.  The head can also rotate to any angle so that cuts can be interlocked to make the best use of the material.  Whilst a plastic cutting barrier board can be used, it is more common to cut on a special conveyor belt which carries the cut parts out of the cutting area.   Fixed Beam Cutting Press   For larger components or multiple small components.  Higher cutting forces permit large or densely bladed dies to be used.   On manual machines, material in sheet form is commonly processed while automatic models can be fed with rolls of material or stack fed with sheets.  Feeding systems and component stripping apparatus can be specified.   Receding Head Cutting Press   This most versatile cutting machine has all the features of the fixed beam press with the advantage of the cutting head or beam retracting (receding) after the cut.  This facilitates the use of larger sheets and roll form material with improved visibility, ease and speed of operation.   Kiss Cutting/Steel To Steel Cutting Machines   Where perfect quality of cut for difficult materials is required or self adhesive components need to be cut onto a backing material, these machines work automatically and at high speed.  Additional positive, mechanical stops allow precise setting whilst rewind stations will wind up the scrap web and the backing material with finished components still in place.   With specialized tooling and equipment these machines can be specified to heat seal the edge of products as well as cutting them out in the same cycle.   Optical Registration Die Cutting Presses   Where products, typically printed ones, demand accurate cutting to registration, it is possible for systems to be equipped with fibre optic or laser sensors which ‘see’ registration marks so that the material is accurately fed and cut to precisely align with the printed image.   APPLICATIONS   With so many models, sizes and types of hydraulic die cutting presses being available the applications for cutting soft or semi-rigid materials are virtually limitless, extending to literally thousands of products, materials and applications.   These include:  gaskets, foam, rubber, plastics, vacuum formings, textiles, carpet tiles, seating, paper, packaging, envelopes, plastic and credit cards, insulation, shoes, leather goods, belts, bags, luggage, medical products, toys, hats, to name just a few.   This insight into hydraulic die cutting has been compiled by Bob Cosford, Managing Director of Global Cutting Technologies Ltd.   Bob has 40 years of experience in the industry and has gained extensive knowledge by being associated with most model ranges, suppliers, machine manufacturers and application throughout his long career.

Keywords: cutting, cutting presses, die cutting, Die Cutting Presses, Fixed head cutting presses, Flatbed cutting machines, Foam Cutting Machines, Foam cutting presses, Gasket cutting machines, Gasket cutting presses, Kiss cutting machines, Plastic cutting machines, Rotary Die Cutting Machines, Rubber Cutting Machines, Second hand cutting presses,

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