Tips for Optimizing or Expanding Your Anodizing Line

Q: I’m looking to optimize and expand my anodizing line. Do you have advice for auditing my current process for areas of improvement?

Process audits are a proven method of identifying issues and opportunities to improve a process. Qualified professionals experienced in specific disciplines can be engaged to support this type of effort, but there are significant benefits from an initial self-assessment. As with many things, the hardest part is getting started. This article offers guidance for an audit and tips for optimizing an anodizing process. Let’s get started!

The axiom “begin with the end in mind” certainly applies when evaluating potential improvements to an anodizing operation. Begin by defining an end-state based on desired competency, capacity and quality. Take a holistic view that includes each aspect of the current manufacturing operation from incoming material to final packaging to identify the limiting steps. Limitations are, in many cases, related to capabilities, resources and process controls.

Benchmarking current capabilities is a worthwhile exercise on its own. Measuring current performance against key objectives will highlight areas for improvement. Establish specific targets for desired capabilities before developing an action plan.

Common examples of resource limitations are materials, chemical processing, people, equipment and facilities. Quantifying the relative impact of each identified limitation will help to prioritize future actions. Look for interrelated areas. Be aware that improvements in one area may well create a bottleneck in another. Fully consider the efficient utilization of staff.

Process control can take different forms, including the required steps, procedures used, and equipment controls. An anodizing process has a number of steps defined by the type of oxide layer and appearance required. Typical steps are as follows: pretreatment including cleaning, surface modification (etching, brightening), deox desmut, anodizing (Type I, II or III), coloring and sealing. Rinsing is required between all of these steps. The operating procedure will define the individual steps and immersion time in each bath. The people control the process on a manual line; control of automated systems is by means of software and the equipment. Selecting, defining and controlling all of these aspects influences the output of the operation.

Develop improvement plans relative to the various materials, processes and operations that include specific, measurable goals. Set priorities by quantifying the resource disparity between the current state and desired output for each of these areas. The guidance provided in this article will help with this initial self-assessment and action plan. Obtaining input from a consultant or supplier will enhance a more in-depth analysis.

Incoming Material

Start with the alloy of aluminum used to make the incoming parts. Different alloys will likely require different choices in processing for optimum surface finishing. Variations between alloys and even lot-to-lot variations of the same alloy can affect the outcome of an anodizing process. When possible, process common alloys and lots together. Know your alloy.

Machine oils, tumbler debris and fingerprints, if not removed, can show up as cosmetic defects. Evaluate all the steps used for incoming inspection and material handling once the parts are in-house to address issues and increase process success.

Anodizing Process

Expertise is required to design and optimize an anodizing process for a given range of alloys and parts. Stay current on developments within the industry to identify beneficial chemistries, process steps and parameters. Within a given anodizing process, variables for each tank can include acid concentrations, temperature, rectification parameters and anodizing cycle time. Rinse water cleanliness and flow rate is an important area for consideration as requirements vary based on material throughput. For example, parts with recessed areas, such as tubes that hold chemical solution, will require more rinse time and water flow.

Time studies are a useful method for identifying bottlenecks that limit productivity. Start by listing every step (material handling, racking, loading, immersion, drip, rinse times, dry, unload and so on) and measure typical times for each. Analyze the time “chain” to find the weak link(s). Use minimum and maximum times as an initial approach to improve overall throughput. Consider process changes to address any limiting steps. Some things to look for:

• Inefficient cleaning processes
  • Compare the benefits of acid versus alkaline cleaners
• Long anodizing cycle times
  • Consider additive chemistry for higher current densities or increased bath temperatures
• Inefficient rinsing, drying and sealing steps
  • Optimize cycle times and process parameters
  • Add spray-rinse
• Rectifier voltages and controls
  • Consider the benefits of constant current versus constant voltage control

The benchmarking previously done will provide valuable guidance for identifying and addressing process limitations.

Operation

The most important element for the success of any operation is the people. Having an appropriate number of well-trained and skilled staff is a key factor for success. This applies to daily operations as well as maintenance. Safety for employees should always be at the forefront when addressing limitations through training and facility/equipment upgrades.

Upgrades to anodizing tank line equipment can have a significant positive impact. For manual operations, this may include additional or larger tanks, new rectifiers, improved filtration or additional heating/cooling. Improving the support equipment for material handling and racking can help to improve process flow.

A more significant upgrade would involve automation of the line. A fully automated system can dramatically improve productivity, consistency and quality based on the list below. Implementing or upgrading an automated anodizing line requires a thorough understanding of the desired performance and options for achieving. Engage industry experts in the field of process automation to assist in quantifying the benefits.

Capabilities

• Automated hoist systems can handle large and heavy loads
• Additional process capabilities designed for colors, part size and so on
• Fixed timeway software can maximize throughput
• Random load software can enable flexible production scheduling
• Data logging and reporting can support NADCAP requirements

Resources

• More efficient use of staff
• Higher throughput for better utilization of the facility

Process control

• Integrated control of all system components, including rectifier settings
• Recipe selection for specific loads
• Repeatability for improved yield
• Interlocked alarms for equipment and personal safety

The self-assessment steps outlined above will generate sufficient information to determine the need for upgrading an existing line or implementing a new, automated line. Following these steps will enable you to address many issues directly and identify when and where to make investments.