Types of Marking Media, Uses, Marking Methods

Hello friends, Today I am going to discuss marking media in which we will know what is marking media and how many types of marking media.

Marking media plays a crucial role in the precision marking and layout of guidelines before machining or cutting by hand tools in machine parts and fitting operations. Its primary objective is to ensure the accurate removal of metal from various locations to achieve the desired shape. Common tools involved in metal cutting include drilling bits, milling cutters, grinders, etc.

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Several types of marking media are commonly utilized for these purposes, including Prussian blue, layout dye, copper sulfate, and white wash. Further details about these marking media will be explored in the following sections.

What is Marking Media?

Marking media is employed in metalworking because the hardness of metal often makes drawn lines difficult to discern. This material is applied to the surface where marking is required, enhancing visibility of the lines created by marking tools. In essence, marking media ensures that the markings are distinctly visible on the metal surface.

Types of Marking Media

Marking media can be divided into four categories

  • White Wash
  • Prussian Blue
  • Copper Sulphate
  • Cellulose Lacquer
Types of Marking Media
Types of Marking Media

 

White Wash

White wash, a blend of chalk and water, finds application on coarse structures like castings or forgings. Alternatively, it can be created by combining white glass powder with turpentine oil. This marking medium is primarily utilized on ferrous materials. Its notable advantage lies in its ease of erasure in the event of an error. However, a significant drawback is its susceptibility to being erased or washed away by water, making it suitable for scenarios where temporary markings are needed.

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White wash is integral to chalk string lines, a tool that involves a string coated with chalk dust. This tool proves invaluable for marking extensive projects. To use it, extract the necessary length of the lanyard from its container, ensuring it is taut. Ask a colleague to anchor one end at the desired marking spot, then pull it firmly over the marking position. With your other hand, elevate the thread vertically and release. The result is a straight chalk dust line on the workpiece, enabling the creation of extended markings.

Prussian Blue

Prussian blue serves as a coloring agent for marking on machining surfaces. It involves applying a thin layer of dye onto a metal piece, allowing it to be easily scratched by a scriber or a sharp tool, revealing a shiny appearance. This process results in the formation of a narrow line on the metal beneath the color.

One advantage of Prussian blue is its ability to conceal existing scratches, revealing a clear contrast with the new lines. However, it has the drawback of a prolonged drying time and is susceptible to being erased during the working process.

Copper Sulphate

Copper Sulphate, also referred to as blue vitriol, is a mixture of distilled water with a few drops of nitric acid or sulphuric acid solution. The resulting thin copper coating exhibits strong resistance against rough handling, cutting fluid, or coolants. Its excellent adhesion to finished surfaces makes it a preferred choice for refined surfaces.

The distinctive blue color of the solution, obtained when mixed with nitric or sulphuric acid, contributes to its alternative name. This type of marking media is specifically employed in situations demanding precise and accurate markings.

Cellulose Lacquer

Cellulose lacquer, available in a variety of colors, stands out as the optimal marking media. Recognized as layout die, this marking medium boasts rapid drying properties and is consistently applied on refined surfaces.

Methods of Marking 

The following methods are often used for marking

  • Datum Line Method
  • Center Line Method
  • Marking by Template
  • Marking of Center on Round Rod End

Datum Line Method

In this technique, an initial line, known as a datum line, is established, and subsequent lines follow the direction set by the preceding one. This method is employed in situations where the connected arms of the job conclude at right angles.

Center Line Method

This marking approach is utilized for irregularly shaped jobs. It involves drawing an initial center line, and additional marking lines are connected in relation to this central reference line.

Marking by Template

This marking technique involves the utilization of a template crafted from a thin metal sheet, tailored to match the size of the job. It is particularly effective for marking identically sized jobs.

Marking of Center on Round Rod End

  • During the marking of the center on the round rod end, the following methods are employed:
  • Utilizing Jenny Caliper
  • Employing Surface Gauge or Vernier Height Gauge
  • Using the Center Head of the Combination Set

By Jenny Caliper 

Open the jaws slightly more or less than the radius of a round job, rotate it from four different positions, and then determine the center.

By Surface Gauge or Vernier Height Gauge

Position the job on the V-block and square the surface gauge or Vernier height gauge by drawing lines from four different positions on the job. Connect the opposite corners of the square to form the hypotenuse lines.

Adjust the cutting location of these lines, opening slightly more or less than the center. The point where these lines intersect marks the center of the end of the round rod.

By Center Head of the Combination Set

Place the center head on the job and draw a line.

Rotate the center head, and position the second line at a right angle to the first line.

The point where these two lines intersect indicates the center of the end of the round rod.

Hints to Be Noted While Marking

  1. Thoroughly examine the workpiece drawing.
  2. Identify the datum surfaces from which all markings will be referenced.
  3. Calculate the dimensions and allowances for the workpiece.
  4. Verify the appropriate application of marking media on the workpiece surface.
  5. Begin by marking straight horizontal, vertical, and slant lines, followed by circles, arcs, rounding, etc.
  6. Upon completion of the marking process, clean both the job and the tools utilized.

FAQ Related to Types of Marking Media

Numerous queries arise concerning the varieties of marking media. In this discussion, we will systematically address and answer each question, providing comprehensive insights into the various types of marking media.

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Q 1: Which marking media is poisonous?

Ans: Copper Sulphate is considered poisonous as it is mixed with nitric or sulphuric acid, both of which are toxic.

Q 2: Which marking media is used for casting and forging surfaces?

Ans: White wash marking media is commonly used for casting and forging surfaces.

Q 3: Which marking media provides a clear line on machine-finished surfaces?

Ans: Prussian blue media offers a clear line on machine-finished surfaces. However, it may be erased during working.

Q 4: Which marking media is used on rough surfaces?

Ans: White wash marking media is applied on rough surfaces due to its easy adherence.

Q 5: Which type of marking media is found in different colors and dries quickly?

Ans: Cellulose lacquer, found in various colors, is a type of marking media that dries rapidly.

 

So, friends, I hope you all know the types of marking media and their uses very well.

If you have any doubt then you can ask me through a comment.

Thank You

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