As a manufacturer of custom aluminum die-castings for various industries, Texas Die Casting, Gladewater, Texas, is no stranger to the creviced surfaces of many types of castings. Cleaning and drying these parts can be a time-consuming challenge, a challenge the company had met adequately until it was faced with a control body casting requiring deburring.
"This is one of the most intricate parts we cast," said Jimmy Choate, supervisor. "The customer wanted a deburring operation, and they wanted it immediately. We had to build a parts washer, but our problems really began when we went to dry the castings."
The four-inch-by-four-inch-by-one-and one-fourth-inch aluminum casting has several three-quarter inch deep crevices on one side. During the deburring operation, a burnished finish is put on the parts that are then cleaned with an aqueous cleaner followed by a clear water rinse. "Generally, it takes a couple of weeks for the product to be used by the customer," Mr. Choate added. "If you have any cleaning residue or moisture left on the parts, they will develop oxidation quickly, since they are aluminum. If there is oxidation, we will hear about it."
To avoid the problem, Texas Die Casting re-evaluated its drying system. It was not satisfied with the centrifugal air blower and airknives it had purchased several years ago. When used in combination with air nozzles, the system had done a fair job of drying other castings but it could not dry these parts quickly enough to meet its customer's deadline.
Still believing that the solution to Texas Die Casting's drying challenge lay in the use of air blowers and airknives, David Capp, purchasing agent, contacted Republic Sales in Dallas, Texas, a distributor of high-velocity drying systems manufactured by Sonic Air Systems, Inc., Brea, California. During visits to the plant, Republic's representative custom-designed a drying system using a Sonic SAS-1000 blower with a 20-hp motor, one 36-inch Sonic XE Airknife and 28 air nozzles.
The system is positioned at the rinse exit and just before the heating oven. Originally, the casting manufacturer had determined the parts must be standing up in order to dry, but the high-impact velocity of the air system stripped the moisture off whether the casting was standing or not.
The difference in performance between the two airblower/airknife systems may be traced in part to the new design of the Sonic airknife. Compared to traditional round-tube airknife configurations, this new design increases exit velocities by nearly 30% and impact air velocities (those measured at the surface of the part to be dried) by 65%. The system is also used to dry other types of castings.
Texas Die Casting knew better than to send the parts to the customer before it could guarantee the castings would be dry. "It is a tough business, and we were not satisfied with the results on this job at the beginning," Mr. Choate stated. "It paid off to keep searching for a drying solution. The Sonic equipment proved it could do the job."