3D printing in metal casting

3D PRINTING IN FOUNDRIES IS A COMPETITIVE ADVANTAGE

Additive manufacturing technology is nothing new in metal casting. Most Czech foundries have worked with 3D printing at least in testing sand molds printed on a 3D printer or using models for precision casting. More and more foundries, however, are beginning to use additive technologies to make their own prototypes, giving them the speed and flexibility to offer their customers the initial samples in a very short time. This helps them win tenders for serial production and to capture any imperfections before launching production. 3D printing is evolving rapidly in this industry, often going well beyond mere prototyping.

The best-known application for additive technologies in metal casting is printing sand molds. Modern trends involve using more environmentally friendly construction materials, which allows for almost 100% recycling of base sand not used to build the mold.  

For precision casting foundries 3D printing is used mainly to produce models out of materials replacing foundry wax. One of the most frequently used materials is PMMA (Polymethyl methacrylate). Another alternative for precision casting is using an additive technology called stereolithography (SLA), which allows high-precision 3D printing and an extremely smooth surface.

Foundries also use the most popular 3D printing technology, FDM, which involves applying a molten filament to the surface in uniform layers. Disadvantages of this technology preventing wider application, however, include poor surface quality, as the surface needs to be smoothed after printing, and lower mechanical resistance to pressure in general.

The HP Jet Fusion offers much better mechanical properties, surface quality and significantly faster 3D printing. HP Jet Fusion 3D printers can handle application in serial production. One example in the Czech Republic is the foundry Draxton Brno, which specializes in mass production of casts for the automotive industry. 3D printing helped them eliminate problems with producing a casting for a hydraulic disc brake caliper. The printed part was able to replace the insert for the riser on the pattern plate for the DISAMATIC molding line. This molding line has the capacity for up to 280 sand molds per hour. The original inserts were made of epoxy resins with pieces of foundry putty. However, this design meant that the inserts wore out very quickly, as the putty would fall off and cause sand holes in the castings. They required repair or replacement after every 1000 demoldings, i.e. every two days.

A 3D scan was performed and the data was used to create a new model for the insert, which was then printed on an HP Jet Fusion 4200 3D printer. This model was custom-made and has completed more than 11,000 demoldings since its introduction into the manufacturing process. It does not show any visible signs of wear thus far. The new part design increased its lifespan by at least 11 times. It also saves time on repairing and replacing the inserts, a particularly important consideration in large-scale manufacturing of this type.

Have a talk with our colleagues and test the resistance of parts printed on the HP Jet Fusion 3D printer.