Plastic “C” clamps have allowed anodizers to meet aluminum wastewater regulations and reduce energy consumption while making secure connections and producing top-quality anodizing. Recent advances in clamp design have further improved process efficiency and employee safety.

A clamp with coarse threads reduces the number of threads per inch by 50%,allowing rackers to affix an extrusion to a spline bar in half the number of turns.

As the anodizing industry has progressed and changed over the years due to increased customer demands, new environmental regulations, technological and process advances, and employee health and safety concerns, so have the methods used for holding products during the anodizing process. The earliest connection methods included the tack welding of each aluminum part to a vertical spline bar, or securing the work piece to the bar with aluminum bolts and nuts. These methods created a solid connection, which was critical to good-quality anodizing; however, a portion of the material was unusable because of the connection technique. Damage to the aluminum sections was also much more prevalent, and customer satisfaction was often compromised. In addition, the life of the aluminum nut and bolt was cut short due to the caustic etching removal of the aluminum during the anodizing process. The threads were quickly mismatched and often needed to be cut off simply to remove the workpiece. The additional labor costs involved and the potential loss of usable square inches of aluminum made these old methods of racking undesirable.

Reducing the wasted and damaged material that cut into the bottom line and decreasing racking department costs required a fastener change.

The flexibility provided by the plastic “C” clamps reduced the number and type of racks that were needed in an anodizers’ inventory and, consequently, the cost to produce and maintain the custom racks.

A Shift to Plastic

While changes were needed to improve product quality and process efficiencies, state and local regulations regarding the amount of aluminum allowed in a metal finisher’s wastewater system also became an issue that needed to be addressed by fastener suppliers and rack manufacturers. Titanium was more expensive than aluminum and didn’t have the same current carrying capacity, but its durability and long life made it an attractive option for small part anodizers and for companies that were consistently processing the same piece and associated rack, cycle after cycle. However, many of the medium and larger-sized anodizers that were running a variety of shapes and sizes through their facility each shift couldn’t use titanium clamps.

An operation that is running three shifts per day, seven days a week, can accumulate a high concentration of aluminum in its processing baths in a short period of time. Less stringent regional regulations for filter press and wastewater compositions diminished these concerns for facilities in some rural locations, but many finishers located in metropolitan areas had to begin paying attention to every square inch of aluminum that was used in the anodizing process. The aluminum limits had to be met while still maintaining adequate current carrying capacity, making secure connections and producing top-quality anodizing. Plastic racking clamps provided a sensible solution.

As facilities began using the new technique of securing profiles to a spline bar with plastic “C” clamps, welding stations and buckets full of aluminum nuts and bolts disappeared. The plastic clamps also replaced aluminum “C” sections that sometimes were extruded at the same facility. These aluminum pieces normally were attached to the spline bar by welding or bolting and created a fixed racking system. The workpieces were placed in the mouth of the “C” section and again held with an aluminum bolt. The rack that was created could only be used for specific shapes and sizes of extrusions or brake metal. Comparatively, the plastic clamps could be moved to various locations on a standard spline bar. This flexibility greatly reduced the number and type of racks that were needed in an anodizers’ inventory and, consequently, the cost to produce and maintain the custom racks.

More importantly, the cost of energy was increasing dramatically during this period of time, as it is today, making the plastic “C” clamps even more practical. By using a plastic resin that is electrically inert and nonconductive in place of aluminum, the necessary power went completely to finishing the part and the spline bar, rather than to the fastener being used as a connector.

Ceramic tips have been added to the end of the frame section as an option on some plastic clamps so that anodizers can rack parts back-to-back on a spline bar and receive the same positive effect.

Replacing Titanium Tips

Anodizing process developments also played a significant role as new plastic fastening options were created. The architectural anodizing segment of the industry changed dramatically with the introduction of the “two-step” anodizing system. This new system provided better efficiencies and increased quality; however, the formulation and process changes required significant alternations in the plastic racking clamp.

Titanium tips normally were placed at the end of the screw portion of the clamp to create a pinpoint racking mark and superior holding power, but the titanium piece left a halo mark on the finished aluminum part with two-step anodizing. Plastic clamps were developed in which the titanium was replaced with an alumina oxide ceramic tip. This diamond-hard tip left a small indentation that was barely visible - no halo mark - and dug into the workpiece to better secure the part to the rack.

Ceramic tips have been added to the end of the frame section as an option on some clamps so that anodizers can rack parts back-to-back on a spline bar and receive the same positive effect. The new anodizing process was a major step forward in saving energy and reducing chemical use in the metal finishing industry, and material handlers and vendors were required to make adjustments in their systems and their product lines to keep pace.

Safer Clamping Solutions

A final area of concern that continues to occupy a growing share of management’s focus is employee health and safety. Reducing potential injuries and stresses on the workforce can provide rewards that go straight to the bottom line and also create a positive and efficient working environment.

Employees in the racking department of large anodizing facilities handle large aluminum profiles by the hundreds each shift. Even material handlers in smaller metal finishing operations are exposed to heavy loads, dangerous chemicals and metal shapes that can cause serious injury. Suppliers and management need to work together continually to reduce the risk of injury and/or the possibility of symptoms appearing due to the long-term requirements of a particularly demanding job.

One recent change developed to address these concerns was a clamp with coarse threads that reduced the number of threads per inch by 50%. Rackers can now affix an extrusion to a spline bar in half the number of turns. At the same time, a short screw option was developed that not only made fastening easier for the racking department personnel but also reduced the possibility of hitting the extended screw portion on the side of the anodizing tanks for the crane operators. Securing or removing profiles from a work bar became significantly less stressful with a few basic design changes.

Most industry changes, like the evolution in clamp design options described here, are the result of people from the various aspects of an efficiently run business coming together and discussing concerns, ideas and solutions. When each segment of the operation is considered, the outcomes often benefit the company, the employees, the suppliers and, most importantly, the customers.

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