3D Bas-Relief Medals

posted Jan 8, 2014, 12:38 AM by Abdallah Absi   [ updated Jan 24, 2014, 12:22 AM ]

December 2013 - Recycled Papers from Absi Co



3D Bas-Relief Medals

Table of Contents




3D Bas-Relief Medals

Table of Contents

What are 3D medals?

3D Artwork

The Stamping Die

Classical Approach Of Producing the Stamping Die

The work of Mr. Mohammed Taufic Absi

Modern Approach Of Producing the Stamping Die

Finishing the Stamping Die

Stamping Dies for Proof-Like Medals

Sample Images of Stamping Dies

Minting or Stamping medals

Sample Images of Bas-Relief Medals

Conclusion


What are 3D medals?

3D (3 Dimensional, 3D Relief or bas-relief) medals are medals with bas-relief carvings. Bas-relief is a kind of sculpture in which shapes are carved so that they are only slightly higher than the flat background and no part of the modeled form is undercut. The projecting image in bas-relief sculptures has a shallow overall depth (1 to 5 scale), as on coins, on which all images are in low relief. In the lowest reliefs the relative depth of the elements shown is completely distorted, and if seen from the side the image makes no sense, but from the front the small variations in depth register as a three-dimensional image. More about bas-relief here.


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3D Artwork

Your unique vision of how your medal will look like is expressed by our graphic designers. A detailed design reflecting the central theme of your message is further developed  from rough hand sketches using graphic software applications. A sculptor uses these designs to produce a first enlarged (3 times the size of the end product) model sculpt in clay using fine cutting and grating tools (view a video about sculpting a bas-relief here).  Alternatively, a virtual model can be created using CAD/CAM software. A combination of both techniques, sculpting and utilizing CAD/CAM softwares, is especially used for human faces.  First the sculptor uses conventional tools to produce a bas-relief model, then a CAD/CAM specialist uses a digital 3D scanner to capture the sculpted model and transform it into a 3D virtual model. The 3D model can be edited (manipulated digitally) e.g. scaled up or down or enhanced etc.


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Enlarged model sculpt in clay

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The enlarged plaster model is cast from the clay model which in turn is used to cast the brass model to be used on a Janvier’s Pantograph machine to engrave a reduced image on a steel die which is finally used after hardening to stamp the impression on brass blanks producing bas-relief medals

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A steel die with an impression engraved on it’s surface, this must be hardened to be ready for stamping medals.

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A medal is produced by striking the steel die against a blank brass (copper, silver or gold) disk.


The Stamping Die

To stamp a 3D impression (the bas-relief) on medals you need a steel stamping die. There are several ways to produce steel stamping dies.

Classical Approach Of Producing the Stamping Die

Classically the 3D clay model created by the sculptor will be cast in brass and reduced to the proper size on a steel die using a manual pantograph or an automatic special 3D reducing machine called Janvier’s Pantograph or Medallion Lathe. After engraving the impression on the steel die it is hardened to make it ready for stamping medals.


The work of Mr. Mohammed Taufic Absi

Mr. Mohammed Toufic Absi was the first one to introduce a Janvier’s Pantograph to Lebanon and to use it in the early seventies. He developed his own pioneering approach to produce his stamping dies: instead of using the Janvier’s Pantograph to engrave the steel die, he used it to engrave a copper plate - a metal softer than steel, a good conductor and offers a very good resistivity to electric erosion- that is used in turn as an anode (or Medal “Master”) in a spark erosion machine known as well as electric discharge machine (EDM) to transfer the impression to a steel die (or “Workpiece”). This approach is not only faster in producing detailed engravings but it has also enabled Mr. Absi to recycle hardened stamping dies when the impression engraved on their surface is of no use. Clearly, hardened steel dies are not suitable for engraving by the Janvier’s Pantograph due to the hardness they acquire through the annealing process. The surface of a steel die is cleared from any impression using a surface grinding machine, then a new impression is engraved on its surface using the EDM machine through the copper plate engraved using the Janvier’s Pantograph.


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A Janvier’s Pantograph machine used to engrave a reduced image on a steel die or a copper plate. The impression is reduced from the brass cast to the right to the small copper plate to the left  in contoured multi-level relief

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Surface grinding machine used to clear the impression from a steel die enabling the reuse of a hardened steel die

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EDM machine used to copy an impression from a “Master” copper plate to a “workpiece” or the steel die


Master at top (copper piece), medal die workpiece at bottom, oil jets at left




Modern Approach Of Producing the Stamping Die

A virtual model created using CAD/CAM software can be utilised to engrave the stamping die in contoured multi-level relief using CAM engravers.



A virtual bas-relief is created based on a simple 2D illustration using 3D software

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A rendered image of the virtual bas-relief to the left: 3D software offers many tools to edit the model and visualise it

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The same model engraved using a small size CNC on a wax plate as a prototype.

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The final medal.

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A virtual bas-relief is created using 3D software based on a simple 2D illustration  of an Arabic calligraphy.

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Finishing the Stamping Die

The die goes through several procedures before it can be used for stamping or coining. It may need to be turned off to be accommodated in the minting collar and minting press. The die is heat-treated to harden it. The exact optimum degree of hardness must be achieved in order to avoid cracking the die under strong pressure while striking.  The die surface may need to be smoothed in case a proof-like medal is to be stamped.


Stamping Dies for Proof-Like Medals

The impressions (the raised areas or the relief) of proof-like medals are frosted and their backgrounds (medal field) are shiny or brilliant (mirror-like) with minor imperfections. The surface of stamping dies used to stamp proof-like medals must be processed in such a way it is highly polished; also the blanks used for minting must be polished.


Sample Images of Stamping Dies


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Minting or Stamping medals

Read information about minting medals here.

View a video about minting medals here.

Sample Images of Bas-Relief Medals

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Conclusion

Production of 3D bas-relief medals involves art and technology.  Though the process can be time consuming and relatively expensive, the 3D bas-relief medals always stands as an aesthetically appealing product.

So, if you are ahead of time, not so tight on budget, and you require medals in large quantities then this might be the option that you are looking for..


To view an updated printable version of this article click here.