Kirloskar Brothers Limited (KBL), a fluid management pump manufacturer headquartered in Pune, India, has turned to additive manufacturing to create valuable cost and time cuts to its spare part supply.
Working with German industrial 3D printer manufacturer voxeljet, KBL has created 3D printed castings for a 3.2 ton (3200 kg) Pelton Runner, used to generate power from the impulse of moving water.
With traditional manufacturing techniques it would typically take KBL upwards of two months to produce the complete mould set needed for this part. With voxeljet 3D printing, the whole process took just a matter of weeks instead.
Ravi Birajdar, VP & Head of Corporate Research Engineering & Development at KBL, comments:
“We use 3D printed molds for all castings that require close dimensional accuracy, very short lead times or simply small batch sizes. At KBL we are also very happy to achieve repeatability and better surface finishes with 3D printed molds.”
A large-scale undertaking for the VX4000
voxeljet’s proprietary technology is inkjet-based 3D printing, covering the standard binder jetting process and the newer High Speed Sintering technology. The processes are compatible with sand, plastic and ceramic materials, with sand well suited to metal casting applications in magnesium, aluminum, iron, steel and brass.
For the KBL Pelton Runner, a total of 20 individual models were required: the cope, drag and 18 bucket cores, which equated to 5.700 kg in silica sand and furan binder. The full job was completed on voxeljet’s biggest 3D printer, the VX4000, which has a build area of 4,000 x 2,000 x 1,000 mm (L x W x H). It took 72 hours to print, and afterwards only required KBL’s proprietary coating for post processing.
After assembly, the model was used to cast a 2.000 mm diameter Pelton Runner in CA6NM stainless steel. The casting had a total yield of 56% (weight of the casting divided by the weight of the total amount of metal poured).
Additive manufacturing the impossible
It is believed that KBL is the first company in India to make use of 3D printed sand molds for metal casting. In addition to Pelton Runners, the company now uses voxeljet technology to produce the complex integral cores of impellers, bowls and Francis runners which are, reportedly, “almost impossible with conventional core boxes.”
According to Alexander Kudernatsch, Vice President of Services at voxeljet AG, “Given the enormous component sizes and the associated volume required by KBL, the VX4000 is the world’s only 3D printing system for the economical and efficient production of the demanded sand molds,”
“It is impressive to see the mold sizes that KBL manages to create with our 3D printing technology.”
Featured image shows the complete steel-cast Pelton Runner made using voxeljet 3D printed molds. Photo via voxeljet