Mass Finishing Water & Compounds, Part 1 – Identifying, Correcting Hard and Soft Water Issues

Achieving the desired surface conditions in a mass finishing process requires the machinery, consumables, compounds, and process water to work together in a balanced manner. Independent of the other process elements, the process water itself must be evaluated for hard and soft water issues.

Rosler has more than six decades of experience designing mass finishing machinery, supplying consumables and compounds, and developing processes. Understanding the ramifications of too hard or too soft process water is a key to our success.

Classifications and Measurements

Depending on its geological source, the water used in mass finishing processes may have varying mineral content levels, specifically calcium and magnesium carbonates, bicarbonates, and sulfates. A high amount of mineral content is used to classify the water as "hard", whereas low mineral content classifies it as "soft".

Based on the contents of calcium carbonate (CaCO3) in the water, the U.S. Geological Survey further describes water as soft, moderately hard, hard, and very hard. The most common classification systems measuring the amount of calcium carbonate in the water are parts per million = milligrams per liter (ppm/mg per L) or grains per gallon (gpg).

Utilizing water that is too hard or too soft can create processing issues including ineffective finishing and system damage.

Water hardness ranges and possible mass finishing consequences include:

• Extremely Soft Water (under 70 ppm) - Because of extensive foaming, compounds can only be used at low concentrations. This dosing is too low for the desired cleaning and/or rust protection effect. To overcome these issues, add a water hardener or defoamer.
• Somewhat Soft Water (70 ‐ 125 ppm) – Water within this range is marginally okay. Foaming may be problematic or manageable depending on the specific water condition and processing needs.
• Optimal Range (125 ‐ 260 ppm) – This is the ideal range for mass finishing operations. No additional accommodations are needed for water hardness levels.
• Very Hard Water (over 260 ppm) – In this range, a higher compound dosing rate is required to prevent calcium salts from leaving spots on work pieces. The compound concentration should be increased until the work pieces are clean and free of spots. In some extreme cases, spots may not be totally preventable.

Types of Foam

Excessive foaming in a mass finishing process is an issue. This foam can have different causes. Thus, understanding what specific type of foam is being produced can help remedy the issue.  

Types of foam in mass finishing processes and possible resolutions include:

• “Dirt” foam – This type is often caused by plastic media fines. By increasing compound dosing rates or, if possible, changing from plastic to ceramic media, dirt foam can be reduced or eliminated. At times a change in the flocculant concentration or type might be needed to solve the problem.

The mass finishing process utilizing plastic media pictured above created dirt foam resembling dense, dirty foam sometimes found on beaches.

• “Surfactant” foam – Excessive compound dosing rates and/or process water that is too soft produces foam. Reducing compound dosing rates is the first step. In case of too soft water, a hardener compound such as Rosler additive CA may be required. A defoamer such as Rosler ES might also be needed to reduce foam.

Surfactant foam resembles foam caused by bubble bath.

Rosler Smart Solutions

Many, if not all of these potential issues with mass finishing water and compound rates can be identified and solved with Rosler’s new Rosler Smart Solutions technology. Using data from water monitoring tests and dedicated sensors, the patent-pending offering monitors conditions and identifies potential problems.

Rosler Smart Solutions brings process knowledge and troubleshooting right to the fingertip of the operator. The interactive troubleshooting guide steers the operator through the corrective actions to prevent unnecessary process downtime and equipment damage.

Versions of the technology are available for shot blasting and mass finishing processes. Rosler Smart Solutions’ first solution in the field of mass finishing deals with process water cleaning and recycling with centrifuges, an area that can be challenging for operators and maintenance personnel alike.

A dashboard displays all relevant equipment and process data, allowing the user to obtain suggestions for immediate corrective action in case of detected problems or deviations.

The Rosler Smart Solutions interface provides machine and process insights.

The Rosler Way

“Finding a better way…” is more than a motto at Rosler; it’s our mission. With more than 60 years of experience and a portfolio containing more than 15,000 equipment and consumable products, solving challenges is what we do. Contact us today to discuss your process water challenges!

The Mass Finishing Water & Compounds Series continues with, “Part 2 – Precise Water Flow, Dosing Drive Results.

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