Impeller Cast Using SLA-Printed Patterns
Charlotte, North Carolina, decided to explore alternative casting processes to improve performance and limit lead times. It contacted Tech Cast LLC, Myerstown, Pa., a producer of large, precision engineered invest- ment castings using stereolithography (SLA) rapid prototype technology, an additive manufacturing process that produces objects from CAD models by printing successive layers of curable resin that are hardened via a beam of ultraviolet light. Because an older wood pattern was
N
the only model for the 500-lb. impel- ler, Tech Cast needed to generate a 3-D drawing for production of the mold. (T e 3-D printing was handled by a third party.) Despite having to generate a 3-D model from scratch, Tech Cast produced two impellers in corrosion-resistant martensitic stain- less steel at nearly equal cost in half the time as the traditional method. “It took us about two weeks to produce an SLA prototype,”
The stainless steel impellers measure 30 in. in diameter and weigh 500 lbs.
said Shawn McKinney, general man- ager, Tech Cast. “Actual manufacturing time, from receipt of the prototype to delivery of the casting, was four weeks.” Cast nearly to net shape, the
components required significantly less machining and avoided the time-consuming welding/grind-
ing loops that typically were neces- sary with green sand casting. In all, the lead time dropped to six weeks from the previous 12 weeks. Addi- tionally, no defects were discovered on the impellers. T e order was relatively small, but
Tech Cast’s ability to produce the castings quickly and cost eff ectively has resulted in additional opportuni- ties with SPX. While Tech Cast plans to continue
to receive its 3-D molds from an out- side vendor, additive manu- facturing can reduce tooling costs and lead times, which can make investment casting
more competitive by reducing lead times for short-run components. “Traditional investment cast
tooling can take 8-12 weeks to build and may require signifi cant
SPX’s BB2 is a horizontal, single-stage pump used in a variety of heavy duty applications.
capital investment, both of which can present barriers to entry into this manufacturing process,” McKinney said. “T e use of additive manufactur- ing technology to produce quality investment castings represents an area of organic growth opportunities for investment casting manufacturers to expand their businesses.” ■
Sept/Oct 2015 | METAL CASTING DESIGN & PURCHASING | 37
eeding to replace two double suction impellers with 30- in. diameters, SPX,
Page 1 |
Page 2 |
Page 3 |
Page 4 |
Page 5 |
Page 6 |
Page 7 |
Page 8 |
Page 9 |
Page 10 |
Page 11 |
Page 12 |
Page 13 |
Page 14 |
Page 15 |
Page 16 |
Page 17 |
Page 18 |
Page 19 |
Page 20 |
Page 21 |
Page 22 |
Page 23 |
Page 24 |
Page 25 |
Page 26 |
Page 27 |
Page 28 |
Page 29 |
Page 30 |
Page 31 |
Page 32 |
Page 33 |
Page 34 |
Page 35 |
Page 36 |
Page 37 |
Page 38 |
Page 39 |
Page 40 |
Page 41 |
Page 42 |
Page 43 |
Page 44 |
Page 45 |
Page 46 |
Page 47 |
Page 48 |
Page 49 |
Page 50 |
Page 51 |
Page 52 |
Page 53 |
Page 54 |
Page 55 |
Page 56 |
Page 57 |
Page 58 |
Page 59 |
Page 60