Investment Casting replaces machined part


By: P. F. Foley Harcast Company, Inc.


The holding device for a packaging machine was orig- inally designed to be machined from 31


/2 x 2V2 x 112


hot rolled SAE 1020 angle stock. However production of the part required sawing, milling, drilling and belt grinding operations with a ready-to-use cost of $5.20 each. After consultation with the customer, it was determined that this same part could be investment cast in 4130 alloy at a drastically reduced cost of only $.98 each. The investment cast part required no sec- ondary operations and is used by the customer as received from the foundry. Amortization of a $195.00 tooling charge was attained with the first "46 pieces. The investment cast part a lso produced a tensile strength about twice that of the angle iron. Radii and


Investment Casting replaces welded part


By Owen W. Hale Independent Steel Casting Co.


Changing from a weldment to a heat treated stainless steel investment casting - improved performance and reduced part cost.


Designing the slim finger yoke, for a recriprocating compressor as a one piece casting has enabled a com- pressor manufacturer to gain improved quality and more consistent physical characteristics of the yoke, the part which positions the valve ring in the inlet valves to unload the compressor.


The part was formerly a steel fabrication consisting of a machined body with eight fingers silver soldered to it. The fingers were produced on an automatic turret lathe and after assembly, the critical dimensions were machined and parts plated.


An investment caster was called upon to produce this part as a one piece casting of a material that would


Investment Casting replaces ceramic molded part


By: W. A. Dubovick Engineered Precision Casting Co.


Improved performance was obtained by changing from a ceramic molded part to a heat resistant stainless steel investment casting for a burner mixer nozzle. The ceramic had fine heat-resistant characteristics but was deficient in other areas. Abrasiveness of the ceramic produced heavy parting lines and limited the detail that could be incorporated in the design. Inability to weld or machine the ceramic made it difficult to match or fit it with other metal components of the burner system. Surfaces were not as smooth as were required by the design and function of the part. The combina- tion of excessive parting lines and poor surfaces re- sulted in excessive turbulence and poor efficiency.


4 TOP AND BOTTOM VIEW OF CASTING


withstand severe physical loading and at times a corrosive atmosphere.


The part was cast using 17-4 stainless steel and heat treated. Only the inside locating diameter and pin lengths were required to be machined.


The results were so impressive that four different size yokes with up to twelve fingers are now being produced as an investment casting together with the correspond- ing valve seats.


fillets of cast parts eliminated the notch effect of sharp machine cuts.


These castings reduced material storage, inventory con- trol, and manpower, as well as freeing the customer's machine-shop equipment for more profitable work.- All this plus a cost per part saving of $4.22 each.


CERAMIC MOLDED PART INVESTMENT CASTING


The smooth surfaces of the investment casting, smooth, unbroken transitions at curved surfaces, narrower rib sections, and negligible parting lines resulted in greater BTU output. The investment casting can be welded, brazed or machined for most economical assembly with other parts.


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