Bronze

More than 3000 years ago, mankind became aware of the importance of bronze. This extraordinary material shaped an entire era that became known as the Bronze Age. From that time until today, bronze has not only been used for the production of a wide variety of objects in the industrial casting process, but has also taken on a significant role as the main material in art foundry. Bronze sculptures developed into a unique style of art and today adorn squares in capitals around the globe.

The presence of bronze in lecture halls, universities, galleries, museums and exhibitions is inevitable, as these wonderful works play an essential role in the design of these spaces. Bronze has a characteristic "metallic timbre" and bell bronze delights tourists and locals alike with its enchanting sound.

In addition to its artistic significance, bronze has served a practical function in society for centuries, protecting people from infections and viruses. The antimicrobial properties of bronze are well known, and many pathogenic bacteria have been found to die within minutes on bronze surfaces. This is one of the reasons why antique door handles were often made of this wonderful alloy.

For already 300 years our company as a bronze foundry has been dedicated to the production of artistic castings for lovers of this impressive genre. Our products range from small bronze sculptures for offices and interior elements to impressive facade elements and monumental sculpture ensembles.
Each of our products is made with great love and care by our master craftsmen, who pour their warmth and dedication into each piece. They pay meticulous attention to every detail to achieve unsurpassed quality and aesthetic beauty.

Bronze casting - the process

How are bronze sculptures created?
Bronze casting is a process for making objects from bronze, an alloy of copper and tin (and possibly other metals). This process has a long history and has been used for thousands of years to create works of art, sculptures, tools, weapons and various other objects. In addition to the sand casting process, the lost wax casting process is usually used.

The bronze casting process involves several steps:

  1. Modeling: An original model or sculpture is usually created from an easily moldable material such as clay or wax. This model serves as a template for the later bronze mold.

  2. Mold making: To make a bronze mold, the model is embedded in a moldable layer of material, often with a core structure to support internal cavities. Then this mold is heated to remove or melt the original model. What is left is a hollow mold that is the exact negative of the original model.

  3. Bronze casting: Molten bronze is poured into the prepared mold and cooled and solidified therein. The mold is removed once the bronze has hardened, exposing the actual casting.

  4. Finishing: The cast bronze object can now be freed of excess material and finished to refine details, smooth surfaces, and perform other necessary steps.

The properties of bronze and the advantages for bronze casting

What are the special features of bronze casting?
Bronze is an alloy metal composed primarily of copper and tin, but may also contain other additives such as aluminum, nickel, or phosphorus. Bronze has been used for centuries in a variety of applications, including art, jewelry, statues, tools and mechanical parts. It offers several advantages like patination and chasing for post-casting finishing compared to other metals:

  1. Good machinability: Bronze is known for its excellent machinability. It can be cut, drilled, milled and turned well. This makes the finishing of cast bronze parts relatively easy and precise.

  2. Low tendency to crack: Bronze has a lower tendency to crack during machining compared to some other metals. This reduces the likelihood of unwanted cracks or fractures during finishing.

  3. Low thermal conductivity: Bronze generally has a lower thermal conductivity compared to materials such as steel. This can be an advantage when machining cast parts as heat spreads less quickly through the material, which can reduce the risk of warpage or undesirable changes in material properties.

  4. Good surface quality: Bronze often has a smooth and attractive surface after casting. This facilitates post-processing, as fewer unevennesses or irregularities need to be corrected.

  5. Customisable alloys: Bronze can be customised by varying the alloy composition in terms of copper, tin and other additives. This allows properties such as hardness, strength and corrosion resistance to be optimised according to the requirements of the application.

  6. Corrosion resistance: Bronze is generally corrosion resistant, especially to atmospheric conditions. This can reduce the need for extensive surface treatment after machining.

However, it is important to note that the advantages of bronze for finishing can depend greatly on the exact alloy composition and the specific requirements of the application. In some cases, other metals could potentially also offer good options for finishing depending on the desired properties.

Typical problems of bronze casting

Several typical problems can occur in bronze casting that can affect the quality and integrity of the final product. Here are some common problems:

  1. Porosity: Porosity refers to small holes or pores in the cast bronze part caused by trapped gases. This can affect the strength and tightness of the part.

  2. Shrinkage: As the molten bronze cools, it contracts, which can lead to undesirable shrinkage or deformation effects.

  3. Inclusions: Foreign particles or impurities can get into the casting material and cause inclusions in the final product which can affect the structural integrity.

  4. Incomplete filling of the mould: If the molten bronze does not flow completely into the mould, this may result in incomplete or uneven parts.

  5. Voids: Voids are cavities or inclusions inside the casting that may indicate uneven cooling or problems with the casting material.

  6. Poor surface quality: Unevenness, scratches or cracks on the surface of the casting can affect the aesthetic quality and may require additional machining.

  7. Surface coatings: Irregular or unwanted deposits on the surface of the casting can be caused by reactions between the mould coating and the molten bronze.

  8. Overheating or burning: Excessive temperatures when melting the bronze can lead to excessive oxidation, which can affect the metallurgical composition.

  9. Temperature gradients: Uneven cooling can lead to internal stresses in the casting and promote cracking.

  10. Mould wear: The moulds used for casting can wear out over time and have a negative impact on the quality of the castings.

Most of these problems can be minimised by careful control of the casting process parameters, selection of high quality materials and regular maintenance of the equipment. It is important that experienced professionals of a bronze foundry monitor the casting process and take appropriate measures to ensure the quality of the final products.

References

Examples of our bronze casting works

Benefit from our generations of experience in the production of excellent bronze sculptures and products.