Core Blower saves small foundry $30,000/Yr, eliminates coreroom personnel.

(Case History)
Publication:Modern Casting

As a 20-employee aluminum and ductile and gray iron jobbing foundry, Southern Cast Products, Inc. (SCP), Jonesboro, Arkansas, must select the appropriate process and tooling for its products carefully, especially in light of current economic conditions. SCP, which casts components ranging in size from a few ounces to 1000 lb, had been using nobake molds and hotbox shell cores to produce its castings. However, to improve productivity and reduce costs, the foundry wanted to convert to phenolic urethane cores. The problem was that it could not justify the expense of traditional coldbox equipment and the necessary supporting equipment such as scrubbers and air handling systems.

Instead, SCP turned to Palmer Manufacturing & Supply, Inc., Springfield, Ohio, and its CM-Series Coremaker-25 Nobake core blowing machine. The CM-Series is designed for use specifically in jobbing foundries where wooden split and dump coreboxes are the norm. Typical conversions are from shell, coldbox and oil sand, and the machine is intended for general runs from 1-100 pieces. As a nobake machine, the core blower doesn't require gas, so money doesn't have to be spent on supporting air system equipment.

In operation, a corebox is placed on the table, the table is clamped and sand is blown into the box. The blowing of cores continues until the blow chamber is emptied or the resin system work time has expired. The unit works with any air setting binder and can be outfitted with an optional coldbox gassing attachment.

The system also can be outfitted with the supplier's High Speed Continuous Mixer, which allows it to productively feed the blow chamber or, in a rotated position, feed a molding conveyor system. This provides the unit with the added flexibility of both coremaking and molding on the same machine. With the optional mixer, the core machine operator can feed the blow chamber or swivel the mixer 90[degrees] to a side discharge point for molding or hand ramming of cores on a table or conveyor.

The foundry ran a test core from a 6-cylinder exhaust manifold that had previously been produced as a hotbox shell core. This core was too large for the foundry's shell machinery and had to be produced as a two-piece nobake core. This process required pasting and mudding at the parting line (causing additional time, defects and rework). Using the core blower, the core was blown in one piece using three-part phenolic urethane sand. The foundry's savings from this core justified the cost of the machinery.

Since then, SCP has switched to the system for all of its core production. Eighty to eighty-five percent of all cores are blown with the remaining hand rammed with the mixer side operating position. These changes have reduced the number of coreroom employees from two to one. The remaining coremaker now can complete his tasks without overtime, which previously ran 20-30%. In addition, scrap defects related to under-rammed cores almost have been eliminated.

SCP estimates that its total annual savings are $30,000. "Since purchasing the Palmer CM-25, we have not only improved our core quality and productivity, but also added tremendous flexibility to our coremaking operation, which is vital for a small jobbing shop," said Doug Imrie, SPC owner.