Investment Casting

Investment casting is among the oldest industrial manufacturing processes still being applied today. Its history can be traced back to 4,000 BC. At this time, bee wax and other animal greases were used instead of synthetic waxes employed today. Samples of sculptures crafted with investment casting have been found in Europe, Asia, Africa, and South America. It took until the 20th century to develop the technology industrially – 400 patents were registered between 1900 and 1940, especially in the defense and health sectors.  

Many materials are suitable for investment casting: stainless steel, alumnium, carbon steels, brass or glass. The process is based on inverting the desired material in a hollow mould inside the breaking material. This hollow mould is an exact copy of the desired final piece. Due to certain characteristics of the breaking material, the superficial quality of the piece is very high, reducing the need for secondary operations.  

The first step consists in fabricating a metallic mould (mostly made of aluminium or steel), into which wax is injected in the form of the desired final piece. In order to maximize the yield, this form is then melted together with other identical units, allowing to continue working with conjunctions of units. The configuration of these conjunctions is crucial to control the process and cost across the whole production.  

The conjunctions are then coated with several ceramic shells until they have reached the necessary resilience for the following process steps. The integrity of the process depends on the employed materials as well as the temperature and air moisture in the work rooms and the drying process of each ceramic shell.  

As soon as the desired ceramic structure is reached, the wax is removed with an autoclav, using the correct pressure and temperature settings and taking care that the ceramic shell is not damaged – creating the ceramic hollow mould. The desired final material is injected into the hollow mould and, after it has hardened, the ceramic shell is removed by vibration and shaking processes. Eventually, the single units are separated and the necessary end operations effectuated to correspond to the clients’ wishes.  

The main advantages of investment casting are:  

• Freedom of design: Produce complex pieces, even wit complex inner structures.  
• Cost advantage: Produce pieces with precise finish and tailor-made design, lowering the weight of the pieces.  
• Repeatability: By repeating the production units, homogeneous quality can be safeguarded.  
• Versatility: Produce an ample variety of alloys.  
• Flexibility: With investment casting, you can produce very small volumes of a few hundred pieces as well as higher unit numbers up to several millions.  

Maybe, you can count among the disadvantages of investment casting that you need to produce a mould for each final piece, as well as high working efforts. Compared to other, faster technologies such as MIM, investment casting takes more time. These factors, as well as the limits of the pieces’ sizes that the technological equipment of the manufacturer can impose, make it necessary to examine in detail which tecnology is apt for producing a certain piece.  

The Ecrimesa Group is looking back at more than fifty years of experience in the realm of investment casting. With more than 2,000 projects in our portfolio, we have a rich experience in producing carbon and stainless steels.  

We have our own office for any adjustments of the design and the fabrication of prototypical moulds, enabling us to offer our clients complete consulting services in order to adapt their design  perfectly to the process of investment casting. Our designers and metallurgic engineers use simulation softwares like Magma Soft and Inspire Cast. 

We use 3D printing for rapid prototyping without having to produce the mould directly, which is very beneficial at the beginning of the process, when the customers’ vision of the desired piece is not complete yet and different samples have to be examined before making the final decision on the mould. This avoids the necessity of producing a mould for each sample, avoiding extra costs.   

We have our own metallurgic laboratory with more than eight technicians, where me conduct continuous controls if the melting process and heat treatments. Moreover, we can conduct X-Ray scans, digital tomography, corrosion controls and material examinations.  

In 2005, we incorporated a machining plant into our company group in order to offer our clients fully finished pieces. Internalizing all machining processes enables us to offer more versatility in the design phase as well as the finished yields.  

Following this philosophy, we also have our own facilities for heat treatments, with 4 lines for hardening and tempering, including stanradized carbon control, 3 lines for hardening and a line for aluminium T6 treatments, all of them CQi-9 certified. With us, the customers receive everything out of one hand, from the design and planning up to the final piece – always with maximum quality.