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Application Overview:

AlliedSignal Automotive Brake Division manufacturers 50,000 castings a day as a tier one supplier to the "Big Three" automotive companies. Most of the castings (made from ductile iron at this foundry) are key components of automobile brakes, such as the housing and calipers. These castings are made by using mold patterns and core box molds. A core box is the mold pattern that makes a cavity in the finished casting. In other words, to make a casting with an internal cavity, you must create a solid mold aorund, which the molten iron can be poured. These solid molds, which are made from sand, are created using a metal core box. Sand and other residues must be cleaned on a regular basis from the core box molds that are used to create the cores.

Project Schedule:

Since most of the castings are semi-spheres, it takes 25,000 cores to make 50,000 full castings. Thus, a lot of solid sand cores are made each day. To generate production quantities such as these requires an inventory of 20 to 25 core boxes and operating three core boxes three shifts, 24 hours a day, five days a week. These core boxes need to be cleaned approximately every two and a half days. A core box is composed of a cope (the top) and a drag (the bottom) and on average are 32" x 40". They are critical to the production of castings and can cost up to $65,000.

Substrate:

The core boxes are composed of tool steel and have several brass vents on each cope and drag to allow air to escape when the cores are setting.

Special Concerns:

The core boxes must be thoroughly cleaned without any metal deformation, as the manufacturing process has tight tolerances. For example, typical tooling tolerances are +/- .005 inches, while the casting tolerances are generally +/- .02 inches. For this reason, hard abrasives, such as glass or plastic media, cannot be used. In addition, if the surface is not clean, tolerances will be off. Cleaning the brass vents is another critical concern, as they must be clear to allow the core to set properly. These vents are inspected by shining light from the back of the core box to expose any block areas.

Previous Methods:

To clean the core boxes, the previous method involved a labor-intensive hand cleaning with chisels and wire brushes, while the vents had to be cleaned with small amounts of acetic acid. The average time to clean a core box by this method is four hours. In addition, the core box did not usually pass the first inspection.

Equipment Specifications:

AlliedSignal initiated a program to evaluate new methods to improve its mold cleaning. After considering several technologies, AlliedSignal selected the ARMEX® process with an ECO system for containment. The system included an ACCUSTRIP SYSTEM® Model #13, fitted with a #6 nozzle, blasting dry with ARMEX® Maintenance Formula.

Containment:

Of course, blasting dry requires a solution for dust control, especially when the cleaning is to be performed inside the plant. The ECO system provides a modular approach to containing dust while dry blasting. Normally, the ECO system is designed with three walls. Fans pull enough air from the open side across the blasting area that the entire area remains dust free. At AlliedSignal, the ECO is completely closed off to provide a fully enclosed blasting area. The spent ARMEX media is collected and used as a neutralizer in the waste treatment facility.

Results/Benefits Summary:

Utilizing the ARMEX cleaning process at about two pounds per minute at 75psi, AlliedSignal is able to clean its core boxes in 30 minutes. Since workers manually clean 10 core boxes per day, they now are able to clean all of them in five hours. Not only is this a dramatic increase in throughput, but the core boxes are cleaner and pass inspection on the first pass. The savings in productivity provides an eight-month payback. Furthermore, the workers are using a non-toxic, non-hazardous material that is easy to handle and process.

Application Overview:

Critical molds that produce automotive headliners need to be cleaned daily to remove the resin materials and mold release agents that accumulate on the surface. If the mold release and resins are not completely removed, the part being produced sticks to the surface and thus becomes defective. During the mold production process, the temperature of the mold typically reaches 250°F.

Substrate:

Cast aluminum and steel, approximately 40" wide by 72" long, weighing close to 1000 lbs.

Special Concerns:

An acceptable level of clean must be obtained without degrading any of the surfaces of the mold or changing any dimensions of the tool.

Previous Methods:

High-pressure water blasting, 15,000 psi in a wash bay, had been used but it damaged the molds. The customer had also tried several non-soluble medias, which could not remove the residues adequately. At the time of our demonstration, they were ready to purchase a $190,000 dry ice blasting system.

Project Schedule:

Because the problem was so critical, (the fact that they were damaging their molds with 15,000 psi water blasting), the customer was in a hurry to get this problem solved. The dry ice blasting process was the only non-solvent cleaning process that worked until they saw the ACCUSTRIP SYSTEM®. The customer called on a Tuesday saw a demonstration on a Wednesday, purchased the ACCUSTRIP SYSTEM on Thursday, and took delivery Friday. The customer has used about two pallets of ARMEX per month for the last three years.

Equipment Specifications:

ACCUSTRIP SYSTEM Model 13P, as this was the only ACCUSTRIP available at the time.

Containment:

ECO System, model ECO-3 complete.

Results/Benefits Summary:

The customer was able to pull the molds off the production line and dry blasts them with ARMEX. This was successfully completed without cooling the mold down to room temperature as required by the high-pressure water blast system and the dry ice system. The turnaround time to clean the molds went from 8-10 hours down to 30 minutes or less, with a minimal heat loss to the mold. As a side note to this project, all of the dry ARMEX waste is being pulled out of the ECO System and donated to the city for use in the local waste water treatment plant. The city is hauling the waste away at no charge to the customer.

Yamaha Motor Manufacturing Corporation of America builds water jet skis and golf carts at its large facility in Newnan, Georgia, located just south of Atlanta. As on most production lines for this type of equipment, the final processing stage prior to assembly is the application of several coats of epoxy paint to exterior parts. The fixtures holding the parts are subject to paint buildup due to overspray, and if left uncleaned the accumulation will break off and cause defects on the surface of new parts. For years Yamaha has removed the fixtures from the line and sent them to a local job shop where they were cleaned using a vibratory bath containing hot pumice. The fixtures then had to be reinstalled upon return. This process was costly and time-consuming.

When plant engineering received information on the ARMEX®/ACCUSTRIP® process, they responded quickly and requested an in-plant demonstration. The initial presentation resulted in the purchase of a Model 13.

The primary use of ARMEX Blast media and the ACCUSTRIP SYSTEM is to clean the parts trays and hold-down fixtures of the production line; this is done once a week. Cleaning is accomplished inside one of the paint spray booths without shutting down the line to remove the fixtures from the carrier chains. This is a major cost saving and is the result of the non-toxic nature of ARMEX. Spent media is dissolved with water, paint chips are filtered out for disposal, and the remaining effluent goes down the drain to their waste water treatment facility.

A secondary use of the ARMEX/ACCUSTRIP process is in cleaning the welding fixtures found on several robot production lines. Previously these fixtures were cleaned using a high-pressure water blaster, and the average cleaning time was 20 minutes. With ARMEX and ACCUSTRIP, the four square foot surface is completely cleaned in just two minutes or less.

Application Overview:

A Midwestern automobile manufacturer uses carriers (similar to "paint hooks") to convey leaf springs through the manufacturing process. Leaf springs are springs of different sizes that connect the car body to the rear drive axle. The autophoretic (free flowing), rust preventive coating that is applied to the springs also builds up on the carriers. This is a common problem that can cause coating residue on the actual parts being conveyed to fall off, disrupting plant production. This facility has more than 1,700 carriers that must be cleaned whenever build-up occurs.

Substrates:

The carriers are welded from 3/8" steel rod. They resemble a large tuning fork and are approximately 12 inches long and weigh about five pounds.

Previous Method:

The hooks were soaked in an acid bath, then manually pounded with hammers to remove the remaining coating.

Special Concerns:

Effective cleaning was a major concern. The previous method did not remove the coating completely. As a result, repeat build-up occurred more rapidly. However, due to the labor intensive cleaning method, the manufacturer delayed cleaning until absolutely necessary.

Waste disposal and its associated costs also were an issue. The autophorectic coating combines organic polyvinylidene chloride or PVDC (similar to plastic food wrap) with trace amounts of hexavalent chromium. As a result, the mechanical removal process produces waste containing chromium, causing it to fail the Toxicity Characteristic Leaching Procedure (TCLP). This is considered a hazardous waste stream as defined by the Resource Conservation and Recovery Act of 1976 (RCRA) which regulates the generation, transport and disposal of hazardous waste. Proper disposal of hazardous waste is significantly more costly than non-hazardous waste and requires extensive record keeping.

Alternative Cleaning Method Evaluation:

Pyrolysis (high temperature heating), an alternative to chemical/mechanical cleaning, was not an option in this case as the PVDC can generate carcinogenic compounds when removed by this method.

Project Schedule:

Previously, the hooks were taken out of service on weekends in batches of 500 for cleaning and replaced with spares. Hooks were cleaned by plant personnel on an as-needed basis as infrequently as possible.

Now, the customer outsources the cleaning process to an ARMEX contractor, who cleans all 1,700 hooks in a four-week period once very quarter – with no production interruptions and no plant personnel involvement required. All cleaning is done at the contractor's location.

Equipment and Containment Specifications:

The cleaning contractor uses an ACCUSTRIP SYSTEM® Model 13P or 12X inside a stationary ECO System 2 enclosure for containment. The ECO System 2 is a steel-construction, double module with a work area measuring 90" w x 90" l x 90" deep. Designed specifically for dry blasting, the ECO System 2 features a dust collection system integrated into the rear wall.

The ACCUSTRIP is powered by a 185 cfm compressor. The contractor blasts using a handheld, #6 Hi-Pro nozzle and ARMEX® Maintenance Formula XL at blast pressures of 60 to 70 psi. Approximately 1,000 pounds of media is used to clean the entire stock of 1,700 hooks.

Results/Benefits Summary:

The paint hooks are cleaned effectively to bare metal. As a result, the hooks are maintained at a high level of cleanliness, satisfying the customer's preference and eliminating production problems related to coating build-up on the hooks.

The ARMEX System also has solved the disposal concerns related to the cleaning process. With the previous mechanical cleaning method, the process residue failed the TCLP test for chromium at 18mg/L (the action limit is 5.0 mg/L). By contrast, the waste stream produced by the ARMEX® Cleaning and Coating Removal system tests at 2.3 mg/L. Therefore, the waste from the ARMEX System does not need to be treated as hazardous and can be disposed in conventional landfills. This has reduced waste disposal costs by a factor of 10. Since the cleaning is done at the contractor's location, all waste disposal is now handled through the contractor's disposal company. In addition, the customer does not need to track the waste as part of RCRA record keeping requirements. This is a significant time and cost saving as the cleaning process generates approximately 1,000 pounds of dry, non-hazardous waste for every 1,700 carriers cleaned.