Disc 250mm Four Steps Speed Metallographic Grinding and Polishing Machine with Touch Screen

Technical Data Download:
iqualitrol Grinding and Polishing Machine XGrind-311

Brief Introduction:

Single disc XGrind-311 touch screen grinder polisher is suitable for pre-grinding, grinding and polishing metallographic specimens. Since the machine is speed-adjusted by a transducer, it can get 150rpm, 300rpm, 600rpm, and 800rpm, which favors the machine with wide applications.

The machine is equipped with cooling system which can cool down the specimen during primary grinding so as to prevent overheating and damage the metallographic structure.

Featuring easy operation and reliable performance, it is an indispensable device for the factories, research institutions and college labs to prepare metallographic specimen.

Technical Specifications:

Purpose of Grinding and Polishing:

Surface layers damaged by cutting must be removed by grinding. Mounted specimens are ground with rotating discs of abrasive paper, for example wet silicon carbide paper. The coarseness of the paper is indicated by a number: the number of grains of silicon carbide per square inch. So, for example, 180 grit paper is coarser than 1200 grit.

The grinding procedure involves several stages, using a finer paper (higher number) each time. Each grinding stage removes the scratches from the previous coarser paper.

This can be easily achieved by orienting the specimen perpendicular to the previous scratches. Between each grade the specimen is washed thoroughly with soapy water to prevent contamination from coarser grit present on the specimen surface. Typically, the finest grade of paper used is the 1200, and once the only scratches left on the specimen are from this grade.

The series of photos below shows the progression of the specimen when ground with progressively finer paper.

Polishing discs are covered with soft cloth impregnated with abrasive diamond particles and an oily lubricant or water lubricant.

Particles of two different grades are used: a coarser polish - typically with diamond particles 6 microns in diameter which should remove the scratches produced from the finest grinding stage,

and a finer polish – typically with diamond particles 1 micron in diameter, to produce a smooth surface.

Before using a finer polishing wheel the specimen should be washed thoroughly with warm soapy water followed by alcohol to prevent contamination of the disc. The drying can be made quicker using a hot air drier.

Mechanical polishing will always leave a layer of disturbed material on the surface of the specimen. Electropolishing or chemical polishing can be used to remove this, leaving an undisturbed surface.

Grinding and polishing is the final stage in the metallographic sample preparation process and consists of several steps. Each step uses finer abrasive than the previous one, the ultimate goal being to produce a deformation-free, scratch-free and highly reflective sample surface. The sample may need to be examined, either etched or unetched, to reveal the microstructure of the material. It frequently happens that contrasts in the material are only visible after a successful etching step.

After a metallographic sample has been mounted, grinding and polishing creates a flat and even surface. Any potential residue from the mounting process or damage from the sectioning process are ground off to expose the actual microstructure of the sample. Polishing removes abrasions from the previous steps to provide a smooth surface. LECO grinding and polishing instruments ensure that metallographic instruments provide a reliably clean sample that will be ready for further analysis.

Pre-grinder machine is the result of a large-scale research work and the wisdom of the designers as well as the suggestions of the users. As an excellent piece of specimen pre-grinding, the pre-grinder has a lap with a larger diameter compared with the same kind of machines produced in our country and the rotational speed of its lap is quite different form that of the machines turned out in our country in order to meet the requirements of the pre-grinding of various materials. 　　

The working principle of Pre-grinder machine is as follows: clear water provided by a water tube flows into the rotating lap and the abrasive paper flowing over the water throws the water out of the lap as the result of the excentric force of the rotating lap forming a vacuum space before the atmospheric rescuer presses the abrasive paper on the lap tightly. Now it is time to operate the pre-grinding. When the lap stops rotating, the work is done and abrasive paper can be easily taken off.