13 September 2019

3D printed press brake tools


Workshops are increasingly faced with a challenging situation where conflicting factors are combined in a way that is difficult to reconcile:

 

  • pieces of complex shape: today’s products are often engineered with special shapes in order to contain weights, welds, and subsequent processing
  • extremely small batches: the manufacture becomes more and more personalized, following the logic of zero warehouse
  • delivery: very short lead times are required. On the one hand, it is in line with the philosophy of optimising production, but on the other hand it may a sign of poor planning. Nevertheless, those who guarantee fast deliveries often have a great competitive advantage.
  • reduced margins: Bending is still considered a low value-added process, and therefore the price we can demand from the customer is reduced to the bone.
  • looks: With products such as furniture and design objects, the surface must be impeccable. Bend marks and scratches must be removed with lengthy subsequent processing.
3d printed industry components

In the case of special profiles, how can we bring all these factors together? One solution comes from 3D printing, an innovative process that is already revolutionizing many sectors of industry. 3D printing is able to produce complex shaped objects in a short time and with extremely low costs.

 

In this article we will refer to the three main methods of printing plastics: Fused Filament Fabrication (FFF), Stereolitography Apparatus (SLA) and Digital Light Processing (DLP).

 

The first process starts with a plastic filament that is heated in an extruder mounted on a motorized carriage. The extruder deposits the molten plastic in superimposed layers until the finished object is obtained.

DLP and SLA are based on a liquid resin that hardens under the effect of light. The first projects a laser beam that causes the resin to polymerize point by point, while the second uses a sort of video projector to solidify a complete layer in a single step. While the FFF is widely used both at a hobby and professional level, DLP and SLA are typically intended for high-precision uses such as jewelry and dental technology.

As for the filaments, various types of materials are available for every need. The most common are:

 

  • PLA: a bioplastic obtained from starch. It is easy to print, non-toxic, has good mechanical properties but deforms with heat and is not well resistant to weathering.
  • ABS: derived from oil, it is widely used for extrusion moulding. Excellent mechanical characteristics, but difficult to print. It generates small amounts of unpleasant fumes during printing.
  • PET/PET-G: the material used for water bottles, which may also be added with glycol (G) to improve printability. Good mechanical and aesthetic characteristics, resistant to atmospheric agents, but the printing requires particular attention to obtain a good result.
  • Nylon: excellent mechanical properties, higher cost than other materials, absorbs moisture so it is not suitable for all uses.
  • TPU: rubber filament used for flexible or elastic objects
  • Polycarbonate: very resistant, flexible and transparent, but very difficult to print due to the high temperatures required.
3d printing press brake tools

Maurizio Pesce from Milan, Italia – 3D Printing Materials, CC BY 2.0, Link


 

Filaments are available in a wide variety of colors and effects, such as translucent, transparent, metallic, phosphorescent. PLA is also available with the inclusion of wood fibres for an effect similar to MDF, or filled with carbon fibre for greater strength.

 

Let’s now see what the advantages of using 3D-printed bending tools can be.

3d printed punches dies sheetmetal bending
  • any shape: 3D printing allows you to create objects with shapes that are impossible to achieve with subtractive manufacturing, such as milling. The internal volume is usually not filled to 100%: with the use of special patterns we can lighten the piece while maintaining a resistance almost equal to that which we would have with a full object. Thanks to this honeycomb alveolation we can reduce the cost of the material used and the production time. 
  • reduced costs: the materials used have a relatively low cost. Moreover, the printing process, after start-up, is fully automatic and does not require any operator intervention. Therefore, labour costs are almost exclusively limited to design. The Gcode file is generated through dedicated CAMs called slicers. The 3D printers have very low power consumption, in the order of a few tens of W. 
  • short times: a tool can be designed and printed in a few hours. In case of errors, we can modify the design and print a new part with extreme ease.
  • no bending marks: being a plastic material, press brake tools printed in 3D leave no scratches on the sheet metal. For this reason, they are also suitable for stainless steel, aluminium and pre-painted steel. 
  • adaptable to existing tools: With 3D printing we can also produce components to be used in conjunction with traditional metal punches or dies. For example, we can produce round inserts for radiused bends to be fixed to punches or punch holders already in our possession. In the same way, we can produce anti-scratch inserts for dies instead of commercially available nylon inserts. 
  • corrosion-resistant: Plastic tools do not rust and are not damaged by most oils and greases.
punch die 3d print press brake
sheet metal die fabrication 3D printed

Like any other technology, 3D printing of folding tools is not a cure-all. Some limitations restrict its use to certain applications.

 

  • coarser tolerances: As the material is hot printed plastic, material shrinkage is not constant with all geometries. The inevitable tolerances in the compounds can also generate variable printing behaviour. The accuracy we can achieve is usually around a tenth of a millimetre or better. 
  • lower tonnages: The maximum load applicable to 3d-printed punches and dies is about 10-20 tons per meter, depending on the shape of the tools and the material used. It is therefore possible to bend sheets with a thickness of up to 1-2 mm. This is therefore not a limiting factor, as they are mainly used for thinner workpieces. 
  • higher wear: The surface resistance of plastics is obviously lower than that of metal. However, prepainted stainless steel and aluminium sheets have a usually very smooth finish, which reduces friction. In addition, the most suitable application of 3D-printed press brake tools is for small series: as they are not used intensively and for a long time, tool consumption does not become significant.

3D-printed components find many other uses in a factory. For example, we can produce objects like:

 

  • jigs to be fixed to the rear references of a press brake in order to have a correct support of pieces with irregular shapes
  • templates of specific profiles, or of go/no go gauges to quickly check tolerances of bent parts
  • grippers and manipulators for robots
  • tools and equipment for special uses, where buying an ad hoc tool would not be economically advantageous or where delivery times are excessive.

Choose your press brake


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