What is Acid Cleaning?

Chemicals. They absolutely are a necessity of life but unless you’re using chemicals in your profession, you probably don’t think much about them. However, when at home perhaps some coffee spills on your shirt, or your new puppy has an accident on your rug, you’ll likely reach for a chemical cleanser. These types of chemicals are designed for home use. But what about industrial use and manufacturing? What do they use to clean and why? Acid cleaning is a process that chemically alters the materials surface by removing impurities and creating a uniform cleaned surface. Used also for other reasons, in which the following will give insight to what acid cleaning is.

• Pickling; Often referred to as a metal surface treatment. Uses hydrochloric and sulfuric acids to remove impurities from the metal surface. Other acids can be used depending on the alloy.
  • For removal of stains, rust, scale, and inorganic contaminants on ferrous metals, precious metals, copper, and aluminum.
  • The solution is called pickling liquor.
  • The metal alloy is submerged if the pickling liquor for the programed duration. This is determined by the material being processed, the thickness and result needed.
  • Used also in preparation for metal parts that will eventually be plated or welded to ensure uniformity on the surface and create strong bonds during the weld.
  • Chemical deburring is also a function of what acid cleaning will do. This method allows for deburring thin metal parts without damaging them. Mechanical ways or sanding or grinding are not suitable for ultra-thin metals.

What methods are used to clean industrial metal parts?

Cleaning up your workspace is different from cleaning your kitchen to cleaning your car. They all have a standard of satisfaction to what we expect as “clean”. In manufacturing of metal parts having a cleaning process is part of the solution for quality assurance. Cleaning metal parts is going to do several things. It’s going to remove surface contaminants like rust, scale, or stains. It improves adhesion by removing unwanted layers in preparation for plating or welding or painting. A cleaning process also is going to help in corrosion resistance to make the metal surface cleaner by creating a barrier for other harsh chemicals. There are numerous methods used to clean industrial metal parts. Some mechanical while other means are chemical. The methods used do pertain to the type of alloy and the end use of the manufactured parts.

• Sanding: This is a mechanical and at times a hand method. Sanding is used when projects require the deburring of the metal surface, but do not have the cosmetic edge. Often the scratches caused by the sanding are prominent. The process is usually done in steps where larger grits of 800 to 1000, up to 4000, 6000 and higher.
  • Used on metal alloys like stainless steel, copper, aluminum, brass.
• Metal Tumbler Machines: This is a method used for deburring, polishing, cleaning, and rust removal. Some types are:
  • Barrel Tumblers: Larger than other types. Good for higher quantities, larger parts, and used for metal, and plastic parts.
  • Can be used as a dry process or wet process (using water).
  • Types of abrasives or media used in the process: steel, ceramics, porcelain, walnut shells and others.
  • Vibrating tumblers: Smaller units but used often to polish or debur. This type of system uses vibration at high frequency to subject the metal parts in conjunction with abrasive media such as porcelain, steel, plastics, sand and others.
  • Metal tumbler machines are used on metal alloys, precious metals, glass, plastics.
• Ultrasonic Cleaning: This type of system works by transferring high frequency sounds waves through a liquid. The metal parts being submerged are then cleaned by the cavitation process. Think of it as the bubble created and imploding on the metal surface and removing the impurities and rust etc.
• Acid Cleaning: Using chemicals such as hydrochloric and sulfuric acids, the process of acid cleaning or also called pickling is processed on stainless steel, copper, brass, aluminum, and precious metals. Used for:
  • Deburring
  • Removal of rust and corrosion and surface contaminants.
  • To provide a clean and uniform surface in preparation of other processes like painting, plating or welding.

To clean industrial metal parts really comes to an end user’s needs. Speaking with experienced services providers in manufacturing and post processing will give the best options available to your project.

When Should I Use Acid Cleaning?

Using caustic chemicals for cleaning is done every day. We use the products and heed the labels indicating the potential for harm and injury if not used properly. This is amplified in industry for those using chemicals to acid clean. Not only in the use of, but in the storage and disposal of such chemicals. The process is not taken lightly. There are other methods to clean industrial metal parts and it does vary greatly. The use of each depends on a part’s specific requirements and factors. When searching for a service provider or process, you will find there are some hands-on methods like sanding and hand cleaning with solvents. For more automated methods you can find machine tumblers, vibrating tumblers, ultrasonic cleaning, and acid cleaning. Regarding acid cleaning, manufacturers of precision parts that are using this method do so for the following reasons.

• To remove micro burrs and slag from the metallic edges.
• To clean and produce a uniform surface.
• Parts that have a lighter coating of rust or contaminants.
• For metal parts that are delicate in their design and thickness.
  • This process is good for thinner gauges of metals from .0508mm on up.
  • Fine geometry that can be damaged using other methods from hand work to machine tumblers.
• In general, smaller parts are good for this process.
• Good for small batches or for larger lots.

There is no best process for cleaning manufactured metal parts. The details and requirements for each job will guide what methods are better suited. The outcome after all is to produce uniform and high quality parts.