Archive: Feb 2022

Non-reactive Cleaning for Powder Coating

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Growing your business often hinges on expanding your offerings. Perhaps no one knows that better than Midlake Products & Mfg. Co. Inc. Based in Louisville, Ohio, the company got its start as an industrial and custom hinge manufacturer in 1987. What started as a small family operation run out of a garage has grown into a 65,000 square foot facility that produces more than 650,000 hinges per year. Over the years, Midlake has expanded its offerings to provide its customers with a variety of metal fabricated components and machine parts. The company offers laser cutting, CNC bending, welding, hardware insertion and finishing, and continues to investigate capabilities to add to its roster. After several years of consideration, Midlake recently added a powder coating line.

“We didn’t necessarily aspire to be a powder coater,” says Jeff Rich, president of Midlake. “But over the years, we kind of continued to look back and say, ‘powdercoating is something that we’re probably going to need to have in our shop.’”
According to Rich, the company had been outsourcing powder coating for approximately 30 years. Midlake had set the stage for further expansion, but was torn between adding more capacity for existing capabilities and adding something new.

“We had added onto our facility in 2012 with a 20,000 square foot addition,” Rich explains. “At the time we only needed 10,000, but were keeping this other 10,000 square feet available for some new capability. At the time, we weren’t quite sure it was going to be powder — but everything just kept leading back to powder coating.”

Cleaning first
Rich says that the tipping point in the decision happened in 2018 at the metal forming, fabricating, welding and finishing expo FABTECH. Much of his time at the show was spent investigating powder coating and talking to equipment and chemical suppliers. Rich was determined to glean some details to help make an informed decision and recalls that one of the factors that convinced Midlake to move forward with a powder coating line was a pretreatment chemistry that he learned about at the show.

“As we were exploring the potential of bringing powder coating in-house, the cleaning seemed like the first step of that process,” he says.

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Experiment study on the corrosion resistance of the surface metamorphic layer of grinding

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Workpiece will face corrosive problems during its application after the manufacturing process. As the common final process, grinding can generate special metamorphic layer on the surface of workpiece and change the initial corrosion resistance of workpiece. In order to study the corrosion resistance of workpiece after grinding process, the paper carries on combining experiment of grinding and electrochemical corrosion. The characteristic of corrosion resistance of grinding is revealed based on the association of grinding mechanism and electrochemical theory. The corrosion potential of workpiece after grinding is higher than matrix, which shows the grinding surface is difficult to begin to corrode. Electrochemical impedance spectroscopy (EIS) shows the grinding surface has large phase angle, impedance and capacitance characteristic because the metamorphic layer of grinding has good obstructive ability. They reveal that grinding improves the surface corrosion resistance of workpiece. Then the mechanism of the corrosion resistance of grinding is revealed. The special grain boundary formed in grinding with much C element, large clusters and complex shape prolongs the corrosion channel, which reduces the corrosive speed. While, the sensitive hardening structure generated in grinding hardening with much free energy is easy to form the corrosion cell, which will accelerate the corrosion.

Grinding is always the final procedure in the manufacturing process, which will decide the final characteristic of surface layer and its surface integrity of the workpiece. So the grinding has a key meaning to technology level of the modern equipment manufacturing1,2,3. Before the grinding process, the workpiece is always machined by all kinds of cutting process, such as the turning, milling, boring and planning. Therefore, the grinding, on the one hand, needs to lower the machining errors of the former process and increase the machining precision of workpiece, then needs to obtain the high quality of surface integrity in the surface layer during the process on the other hand4,5,6,7. Grinding uses the abradant to remove the materials of workpiece. The grinding wheel has a large linear velocity and the strain rate of the processed material is large8,9. Combining with the cutting effect with large numbers of abrasive grain, large grinding force and high grinding temperature are generated during the grinding process, adding the factors of mechanical vibration.

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