1. Polishing Compound Introduction
We added mass finishing polishing compound to parts and media for different purpose. Firstly it is to increase deburring action (i.e., to add a more aggressive environment). Also it use to remove scale and heat treat tints; scour surfaces. Besides, it can also clean parts, media, and tubs. In addition, compounds modify the luster or color of the workpieces. Still they add corrosion- inhibiting coatings for steels, aluminum, and zinc.
Most compounds are combinations of chemicals that dissolve in water and form solutions to maintain consistency or to modify the action of media against the workpieces in mass finishing. Compounds come in premixed liquids or in powder form. Some compounds contain non-soluble abrasives for special applications, such as part-on-part finishing. The use of too little, too much, or an improper compound can adversely affect the cycle time and/or ability of the media to perform as intended.
2. Functions of polishing compound
The use of abrasive media mandates a mass finishing compound rich in suspending and inhibiting agents. A flow-through solution system that meters compound and water carries the fines or residue that are produced out of the machine. This prevents redeposition of the soil and grinding of the residue into the surface of softer metal parts.
Since the abrasive action produces an active metal surface, corrosion-inhibiting agents become an integral component in the compound.
When the compound does not provide adequate inhibition, flash rusting will occur on ferrous parts, and pitting, tarnishing, or similar oxidation will result on non-ferrous parts. When machined parts are
deburred, especially where coolants are used to machine the parts, the deburring compound should also contain emulsifiers for removing the soil. Lack of a good cleaning property would result in residues and fines smeared and embedded into the oily surface of parts. A properly formulated compound would produce a deburred part that
has a clean, normal, metal-looking surface.
The heavy steel media produces lustrous parts very quickly. The compound used in this process would be specifically designed to keep steel media and parts lustrous, and at the same time prevent their corrosion. This compound is normally rich in chelating agents to produce brightness and color on the parts. The burnishing compound for steel media is probably the most difficult to formulate because it must contain ingredients that would continually clean and protect the steel media from darkening and corroding, as well as rusting when not in use. This compound determines the brightness and color of the parts, as well as the life of the steel media.
We can achieve optimum burnishing action when:
1. the steel media is clean and lustrous
2. the parts need to clean before burnishing
3. the burnishing compound keeps the parts,
media, and process chamber clean and
4. there is maximum contact between part and steel media.
Cleaning compounds do just what their name indicates. In barrel applications these are often the first products used because cleaning or removal of organic soils, such as oils and greases, must be accomplished before anything else can be done to the parts. The same holds true for vibratory compounds and processes. The cleaning compounds must work very fast if surfaces of parts are not to be darkened by the soil embedding back into the surface of the part.
The degreasing compounds are modifications of cleaning compounds. Their primary use is as dry, barrel-finishing products.
The acid loosens the scale and the tumbling media removes it. Because acids cannot cut through oil and grease so we need to remove these substances from parts before use descaling compounds. After descaling we need to rinse parts and clean with a neutralizing solution to prevent long-term acid attack.
Aggressive cutting materials will remove thin scale without the need for acids. Since hydrogen embitterment of some heat-treated parts is a major concern, the finishing department needs to make sure that the acids will not affect the product use.
2.6 Rust prevention
People invented and start to use Cyanides in the 1950s for rust inhibition. These compounds are poisonous and, when mixed with acids, compound fumes from the reaction are highly toxic.
“Corrosion preventative” is a better term than “rust preventative” for this group of agents. Rust is the term for iron and steel oxidation, but any metal will develop an oxide or tarnish