him, what kind of material specifica- tions it would require, and whether it could be cast or had to be machined. He had some basic issues he didn’t have answers to, which our engineer- ing people helped him with.” Tat collaboration resulted in patterns for the turning and fixed burrs, which CTI approved. “He was grinding peanuts in
a very simple and rudimentary way, and we discussed how close we could cast this to the near net shape of the part that was being produced through machining,” said Ahlstrom. “We were able to main- tain the same profile, shape and size. Ductile iron was chosen for its wear properties.” Smith Foundry made sample
castings, tweaked the process where necessary, then went into production using ductile iron grade 80-55-06. “After they are cast and the cast-
ings are cleaned, we put them in a machining process to cut the fine burrs on them,” said Ewing. “Ten, the iron burrs are case hardened in a heat-treating process to about 55 or 60 Rockwell C so they are tough, reliable and affordable. Te grinding burr is withstanding a lot of grinding force and use. Oxida- tion isn’t a problem because of the hardness of the metal, and we don’t run into any rusting or corrosion problems with it.” Te CTI Omega grinder is housed in a cast aluminum body produced by Modern Metals Foundry Inc., Bloomington, Minn. Te Ewing IV grinder is housed in sheet metal with a baked-on coating. Te machines are assembled locally, packaged and sent to Africa, Asia and other locations. “It’s been a tremendous boon for us to have Neil and the foundry people do this for us,” said Ewing. “They give us a good price on the product and meet our requirements whenever we need some. Now we can make large quantities at prob- ably 25% the cost.” Since Smith Foundry began cast-
ing the grinding burr 10 years ago, CTI has placed thousands of these machines around the world. ■
Tikondane member Joyce, pictured with her youngest daughter, has experienced a great improvement in health since the group started its peanut microenterprise.
Mar/Apr 2014 | METAL CASTING DESIGN & PURCHASING | 33
The group in Malawi manufactures peanut butter to support its community of HIV/AIDS survivors.
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