Nopatech™ is a new technology that does patternless castings, a rapid prototyping process ideal for large iron parts. This article presents a case study of a recent order.
Nopatech™ can do large patternless iron castings faster and in a more cost effective manner than ever before
When Nopatech™ was developed in 2010, the money saved for short production runs was expected to be the most important advantage of this technology. Even though the savings are as substantial as anticipated, customers do not choose Nopatech™ for this reason. Indeed, more often than not, Nopatech™ is the technology of choice when time is of the essence.
This was the case when a customer came to us with an order that would have seemed impossible five years ago from any iron foundry: two press castings of 7,200 lbs and two press castings of 6,300 lbs, both with extremely high level of details, had to be cast, cleaned up, painted and shipped in 8 short weeks. Five very good, very fast pattern shops where contacted and, depending on how busy they were at the time, lead times varied between 10 and 16 weeks just for the patterns. The very best lead time that could then be offered to the customer was 14 weeks. Not only was that too long, but the price tag was very high: $78,000 for the four castings.
A challenge for a modern iron foundry
Nopatech™ had not yet done a patternless casting of such size with as many details but it was a very interesting challenge. Even without the fact that these would be done with a very young rapid prototyping technology that had not yet done parts of similar complexity, the castings presented other challenges. The holes in the four corners of both presses could not be done in regular no-bake sand because the heat would fuse the sand to the iron. But the real difficulty was the presence of a long cast-in steel pipe in the smaller press that had to move as little as possible during pouring because it had to be reached by blind machining at six different points.
A fast and cost effective rapid prototyping solution
During the first week after reception of the order, the 3D model supplied was modified to account for the necessities of casting; the model was scaled to account for shrinkage allowance and the gating and risering systems were added. A thorough fluid analysis was done on both castings to avoid in-mould turbulence or shrinkage during cooling, ensuring the structural integrity of all castings. A new challenge was found at that moment: because of the size of the castings, they would have to be kept in the mould for 72 hours after pouring. Since there was only one set of flask for the 4 castings; that would provide one more challenge for this order.
Nopatech™ started machining during the second week. Days and night, it continued machining sand so that a mere four weeks after order, the four castings were cast. The parts were then cleaned and painted, ready to ship after 8 weeks, as promised.
The total cost ended being $55,500, an impressive 29% less that the cost of traditional method. Even more impressive, if you account for the fact that the castings themselves cost $10,000 each, the cost of Nopatech™ was only $15,500, compared to the $38,000 of traditional patterns. That’s an incredible 59% decrease in cost.
