In the first part two fundamental aspects of having a measure of judgment in choosing an electrochemical device were discussed:

• Electrical power and electronic technologies;
• Types of electrolytes.

With these parameters one can get a general view of the situation. To go into more detail, two other parameters that are also fundamental can be considered:

• Safety Devices and Pickling Process Optimization Technologies;
• Type of weld, length of weld.

These parameters focus on business productivity and the way the operator works.

Safety Devices and Pickling Process Optimization Technologies

Pickling machines are devices that convey electric current and an electrolytic solution to clean welds. These two factors if handled incorrectly can harm the operator and slow down the production process.
In the market, some pickling machines are equipped with a “dip&work” system. This system involves a small basin filled with corrosive acid in which the insert is soaked and then the weld is cleaned. This method, in its simplicity leads to numerous defects:

• Continuous interruptions;
• Drops of electrolyte fluid in unwanted areas;
• Welding residue contamination.

The electrochemical reaction is fast and immediate. Locally, high temperatures and chemical reactions are generated between the weld and the end of the insert (which is generally a carbon fiber brush) that quickly deplete the electrolyte. The operator is unable to determine the exact time to re-wet the insert, causing the generation of unwanted fumes and consumption of the insert.

It can happen that acid, impregnating the insert, escapes from the insert before cleaning, inexorably fouling parts that are not involved in the pickling process. This results in damage when the operator, during the process, does not neutralize and acid from the surface. During the pickling the insert becomes impregnated not only with acid but also with welding residues removed over time. With this method, these residues are dispersed within the can at the time the operator returns to wet the insert.

These residues, by contaminating the electrolyte, lower the efficiency of weld cleaning and can create corrosion spots because they introduce unwanted elements back onto the bead.
All these disadvantages impact production activity, causing slowdowns for:

• Small interruptions;
• Neutralization or damage on surfaces not involved in the process;
• Increased pickling time due to residue contamination in the electrochemical solution.

Automatic blowing torch/aspiration- Nitty-Gritty

Nitty-Gritty has developed two patented torches characterized by the ability to draw liquid from a tank (100 ml or 2 liters depending on the model) via an automatic pumping o manual. With this technological leap:

• The liquid directly wets the pad/brush and acts directly on the weld;
• Leaves no residue on other surfaces;
• No liquid comes into contact with the operator;
• There are no interruptions;
• The electrochemical liquid inside the tank is not contaminated;
• Interventions even in hard-to-clean areas.

Sometimes operator safety is a marginal aspect of a business. It must be a priority in this process as the risk of injury is always around the corner. Much discussed is the issue of vapor/gas development during the pickling process. The most dangerous electrolytic solutions are corrosive and high in phosphoric acid. In this case. the exposure limit is 1 ^mg/m3 (TWA, 8h). Manufacturers using dip&work are almost at the limit (about 0.8 ^mg/m3). This implies the potential use of protective masks and antacid gloves.

From this point of view, Nitty-Gritty has studied of the two systems that can radically cut down the development of corrosive gases:

• Vapor extraction system;
• Vapor blowing system.

In this way, hot, corrosive vapors are instantaneously either conveyed into the machine by an expertly designed suction motor for acidic vapors or condensed with a jet of cold air with the right pressure from a compressor connected to the machine. With these technological arrangements, the exposure limit is lowered to a value of about 0.04 ^mg/m3.

Type of weld and its dimensions

A fundamental and indispensable point of electrochemical pickling is the quality of the welded joint, repeatedly mentioned in several articles on this blog. In addition to this very important parameter, there are two other factors that can change the prospects for a good pickling machine purchase. One of these is the type of weld: producing a part with MIG welds rather than TIG welds has a different impact on electrochemical pickling time. The MIG welding produces a greater amount of slag than TIG welding. For these reasons, for the same amount of time, one could choose a machine with a power of 900W or more using an acid with a very high acid concentration (around 75%).

With this solution, many of our customers are satisfied because of the value for money. Similarly, TIG welding will require less pickling power, and solutions with a very low acid concentration (about 20 to 25%) down to 0% acid concentration (neutral pH). On TIG welds, with the same power and weld quality, electrochemical cleaning occurs in the same timing if we were to choose between a mildly acidic solution and one with neutral pH.

Another important parameter is the length of the weld hinges. Simply put, how many meters of weld should be cleaned in a production cycle? If the welding meters are around 200-300 meters, it is worth adopting systems such as Clinox Pro, Clinox Power, Clinox Surface which allow a continuous and automatic process of electrochemical cleaning, taking advantage of very high pickling power.

This eliminates the downtime and continual interruptions of a simple “dip&work” system with all the problems attached to the system and its technology that we discussed earlier. If, on the other hand, the welds are less than 200 meters and are TIG welds, the dedicated machine is the Clinox Eco. With its power (450 W) and its patented torch, it is possible to flawlessly clean all the welds that make up the small workpiece. Unlike welding, the thickness of the steel is not a key parameter because electrochemical cleaning involves only the surface and does not need high power to act in depth.