6 Ways to Improve Medical Grinding and Polishing

Written by: Buehler
Last Updated: August 2026
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Reviewed by: Buehler Lab Team

Why Grinding and Polishing Matters for Medical Manufacturing

Automation is enabling both improved sample quality and throughput for quality critical manufacturing. The automation trend is aiding multiple industries. Often in highly regulated industries, such as in medical, automation need to meet or exceed the quality of production or testing while also increasing output to be commercially viable. Medical grinding and polishing can take long periods of time and be labor-intensive. This is one area where automation is able to meet all regulations, improve output, and even potentially improve the quality of production.

Though inspection is a common and necessary function of all manufacturing, the process is even more important for medical implants. For these products, the quality assurance lab will take samples from parts from the production floor or out of inventory for inspection. The lab sections the sample and encapsulates it into a protective polymer mount. This process is followed by a series of grinding and polishing actions to efficiently remove sectioning damage. In addition, this process levels and cleans the specimen surface to enable accurate inspection.

Grinding and Polishing Is the Last Step Before Inspection

Grinding uses fixed abrasives at the point of cutting—the abrasive particles are generally bonded to paper or a platen—for fast stock removal. The process entails three to five steps using progressively finer abrasive grit before polishing steps are carried out.

Polishing removes the artifacts of grinding while maintaining the integrity of the sample. When correct polishing is carried out, one can then see the true microstructure of the sample/specimen using optical and electron microscopy. Additional tests using a hardness tester can also be performed.

For high-production manufacturing, component testing is generally essential. An example is the application of coatings to orthopedic implants (e.g., hydroxyapatite coating for better biocompatibility with bone tissue).

These coatings and related alloys present metallurgical preparation challenges and demand careful considerations due to their high likelihood of outer structural and microstructural damage during sectioning and grinding and polishing. How efficiently the procedures are carried out and the resultant quality of the sample are crucial for high-volume medical part production.

Traditional manual methods of sample preparation involve long, tedious steps to reveal the true microstructure of a component. The latest developments reflect a thorough understanding of the principles of material removal in grinding and polishing.

Improving the Sample Preparation Process for Grinding and Polishing

These new approaches take into consideration the initial sectioning damage and how each grinding and polishing step reduces the damage level and its corresponding residual structural damage. Here are six impacts for improving this process that semi-automatic grinding-polishing machines have on high-volume quality assurance labs:

Faster Throughput

For high-volume production operations, quality assurance labs are busy through the entire eight-hour shift, and in some cases more than 24 hours. Going from rough cut to polished finish can take up to an hour. Newer grinding-polishing systems take 6 to 8 minutes off the process with the added advantage of processing multiple samples simultaneously.

Reducing Cross-Contamination

Newer machines have self-cleaning features that apply water and spin the platen at a high speed. As the platen spins, debris is removed and the machine is rinsed clean, greatly reducing the potential for cross-contamination.

Reducing Operator Fatigue

With a manual machine, a day of testing can mean a lot physical exertion, leading to errors as time moves on and making this approach unsuitable for high-volume labs. The problem is the need to perform the task manually on a machine that either has a raised platen, or else having to rest the wrists on raised edges and lips during grinding and polishing stages.

The advantage of semi-automatic grinder-polishers is that the machines do the work of applying pressure to the sample during a preparation routine without the need of an operator manually handling the samples. Once the samples are loaded on the machine, the operator can press the start button and walk away until it is time to reload new samples on the platen.

Processing Consistency

Along with handling multiple samples, semi-automatic grinder-polishers provide consistency by applying the same force for each sample as well as the ability to adjust the forces to match different sized specimens.

Repeatability

Semi-automatic grinding-polishing machines can provide a touchscreen to enable the technicians to enter in processing routines for the different materials. The technician can enter the routine on the color touchscreen and recall it from memory when that batch of parts comes into the lab. Panel functions can include time, speed, single/central force mode, head rotation, force, pause/stop buttons, and what actions were used (on/off).

Fresh or recirculated water
Platen
Auxiliary dispensing

Technicians then only have to deal with cleaning the sample between grinding steps.

Reduced Vibration

Most manual grinding and polishing machines have sheet metal bases. A cast-aluminum base on semi-automatic machines greatly reduces vibration during grinding for a more consistent, higher-quality sample.

Medical Products Depend on Accurate Analysis

In the quality assurance process for manufacturing products used to replace human body parts, the grinding-polishing process involves multiple steps that require the selection of proper surfaces and abrasives at each point in the process. The goal is to provide an acceptable surface for examination. While any kind of grinding-polishing system can provide this kind of finish, semi-automatic machines can enable the quality assurance process to keep pace with the high-volume manufacturing happening on the plant floor.

Grinding and Polishing FAQs

Which grit should I start with for metallography?

Grinding should start with the finest grit size that will establish a flat surface and remove the effects of sectioning within a few minutes. An abrasive grit size of 180-240 (P180-P280) is usually coarse enough to use on samples sectioned by an abrasive wheel on a metallography saw – finer for very soft materials. For very hard materials such as ceramics and sintered carbides, choose diamond grinding disks with grit sizes from 125 to 75µm.

The table below shows recommended starting grit sizes for grinding different materials.

Why does metallography require multiple grinding and polishing steps?

In metallography preparation, the cutting step and each grinding step produces damage itself. The depth of damage decreases with abrasive size but so does the metal removal rate. Large gaps in abrasive size would require excessive time to remove the damage from the prior step and is inefficient. 3-5 steps from initial grind to final polish are typically sufficient for most materials. Note that for a given abrasive size, the depth of damage introduced is greater for soft materials than for hard materials, but removal rate is controlled by the harder material. This means that samples with combined softer and harder components often require more preparation steps.

What factors influence the surface finish in metallographic polishing?

Many factors influence the surface finish, such as:

Abrasive size and type
Cloth characteristics (weave, flatness and resilience)
Polishing time
Specimen load
Relative rotational direction
Rotational speed

If help is needed to determine the correct polishing recipe, please contact our applications specialists. Buehler Solution Centers provide materials preparation and analysis training to our customers worldwide. Our mission is to deliver valuable application solutions by employing Buehler methodologies.

What are the steps in a metallographic polishing process?

Polishing consists of two or more main stages, using successively finer abrasives.

Coarse polishing follows grinding and removes the bulk of the deformation created in the grinding process.
Intermediate polishing stages may be required to further reduce surface deformation and leave smaller scratches.
Fine polishing perfects the surface finish by removing any trace of deformation.

How do I know when to move to the next preparation step?

A specimen is ready to move to the next step once all the scratches are uniform and evidence of the previous step is gone. Final polishing on soft cloths should be performed for the minimum amount of time required to achieve the desired results, as over-polishing can damage the specimen.

How long does a polishing pad last?

Often, a cloth may get contaminated from improper care or gouged before showing significant signs of wear. End of life for a cloth is typically indicated by unusually high polish time, a degradation in result or signs of visible damage such as fraying.